KENYA AGRICULTURAL RESEARCH INSTITUTE NATIONAL AGRICULTURAL RESEARCH LABORATORIES KENYA SOIL SURVEY

RECONNAISSANCE SOIL SURVEY OF CHUKA-NKUBU AREA (quarter degree sheet no. 122)

By

P.T. Gicheru and R.M. Kiome

(Wanjogu S.N, P.N. Macharia and G.N. Gachini (Eds.)

RECONNAISSANCE SOIL SURVEY REPORT No. R16. JULY, 2000 KENYA AGRICULTURAL RESEARCH INSTITUTE

KENYA SOIL SURVEY

RECONNAISSANCE SOIL SURVEY OF CHUKA-NKUBU AREA (QUARTER DEGREE SHEET NO. 122)

BY P.T. GICHERU AND R.M. KIOME

RECONNAISSANCE SOIL SURVEY REPORT NO. R16 JULY, 2000 RECONNAISSANCE SOIL SURVEY OF CHUKA-NKUBU AREA (quarter degree sheet No. 122)

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By P.T. Gicheru and R.M. Kiome

RECONNAISSANCE SOIL SURVEY NO. R16 JULY, 2000

12) I?? & FOREWORD

The present soil survey is the 11th in the series of "Reconnaissance soil surveys" with multipurpose biophysical information. It covers toposheet (1 22) at a scale 1:100,000.

The survey area has a substantial variation in annual rainfall with a general decrease from the west to the east. The drier areas have only one season falling in Sept to Dec while the wet areas have two seasons which are reliable and comes in the months of March to May and Oct to December. The variation in rainfall reflects the land use pattern which varies from cash crop growing to subsistence cultivation in the drier areas.

The report shows that the general pattern of the soil resources is mainly determined by the physiography, parent material and climate. Most of the soils in the area are strongly weathered and are generally acid in nature due to leaching especially in the wetter part of the survey area.

Sealing and crusting occurs in areas with soil units classified as Acrisols and Luvisols. These generate alot of runoff when it rains. Rains make these soils very vulnerable to soil erosion. Urgent action is therefore required in these areas to prevent further deterioration of the land. Areas with highly leached soils would require application of lime to neutralize the acid especially where cereals are grown. In low rainfall areas, early maturing crops should be recommended. In steep slopes, especially in the V shaped river valleys, planting of trees is highly recommended. This will form a good protective vegetative cover and will at the same time serve as water catchment areas. Also conservation measures such as terracing are recommended.

The report gives the methodology employed and a simple criteria of land evaluation. All the analysis was done under a very good cooperation between the Soil Fertility Plant Nutrition and Programme and Kenya soil Survey laboratories staff. Special acknowledgement therefore is due to all staff members both from Soil Fertility Plant Nutrition and Programme and Kenya Soil Survey who contributed to the completion of the fieldwork and subsequent reporting.

P.T. Gicheru Head, Kenya Soil Survey June 2000, Nairobi

(i) SUMMARY AND CONCLUSIONS

The Survey area is situated in the Eastern Provinces of Kenya and is bounded by latitudes 0°30'S and 0°00' (equator) and by longitudes 37° 30' W and 38° 00E. The area has a substantial variation in annual rainfall ranging from the east to the west. The drier areas bordering Tana river have only one reliable season September to December. In the wetter areas bordering Mt. Kenya the rainfall distribution is bimodel "» viz. March-May and August-December periods.

The agro-climatic zones are mainly based on climatic study with some support of a current vegetation survey. The ratio of rainfall evaporation (r/Eo) gives agro-climatic zone and it ranges from 80% to 25% in the survey area. The survey area therefore has five agro-climatic zones viz. 1,11, III, IV and V. Land use varies from cash crop to arable mixed farming and grazing. It included areas under coffee and tea cash crops to subsistence crops and grazing in the drier areas.

The rocks underlying the survey area are predominantly volcanic and metamorphic, but there are also recent superficial deposits occupying very small parts of the area. The volcanic rocks include lahars, phonolites, tuffs, basalts and ashes while metamorphic rocks include gneisses and miginatites.

The landforms found in the survey area are related to the geology and the geological history and they include the mountains, hills and minor scarps, footridge, footslopes, plateaus, uplands, plains, major and minor valleys, bottomlands and sinkholes. The mountains and footridges are found in the western part of the survey area while all the other landforms are scattered all over the survey area.

The survey area is situated in the upper Tana catchment basin. The drainage system is dendritic beginning from Mt. Kenya. There are seven main perennial rivers namely Tana, Ena, Thingithu, Ruguti, Mara, Kithinu and Mariara with their tributaries forming a dendirtic pattern. The principle drainage follows the general trend from Mt. Kenya in the west to Tana river in the east. These rivers form the main supply of the water needs in the area. Several boreholes are found in the eastern part of the survey area. The general pattern of soils is mainly determined by the physiography, geology and climate. For the vegetation and landuse of the survey area, the reader is referred to Miscellaneous report no.38 "Vegetation and present landuse of the Chuka-Nkubu area (Macharia,1989).

No conventional land evaluation was done for the survey area. However, in the soil legend the descriptions of the mapping units are followed by ratings in tabular format of 11 soil characteristics and quality (see appendix 5).

(ii) 1. THE ENVIRONMENT 1 1.1 Location, Communication and Population 1 1.2 Climate 3 1.2.1 Rainfall 3 1.2.2 Potential evaporation 4 1.2.3 Temperature 5 1.2.4 Agro-cliatic zonation 5 1.3 Geology and Geomorphology and Hydrology 8 1.3.1 Geology 8 1.3.2 Geomorphology 13 1.3.3 Hydrology 17 1.3.3.1 Surface water 17 1.3.3.2 Ground water 18 1.3.4 Soil erosion and land degradation 18 2. THE SURVEY METHODS 22 2.1 Soil Survey Methods 22 2.1.1 Office Methods .22 2.1.2 Field methods 22 2.1.3 Laboratory methods 22 2.1.4 Cartographic methods 24 3. SOILS 25 3.1 Previous work 25 3.2 General soil properties 25 3.3 Description of the soil mapping units 29 3.3.1 Systematics and nomenclature 29 3.3.2 Soils of the mountains 31 3.3.3 Soils of the hills 33 3.3.4 Soils of the footridges 41 3.3.5 Soils of the footslopes 53 3.3.6 Soils of the plateaus 56 3.3.7 Soils of the uplands 61 3.3.8 Soils of the plains 82 3.3.9 Soils of the major and minor valleys 92 3.3.10 Soils of the bottomlands 97

3.4 Soil classification, correlation and genesis aspects 100 3.4.1 Introduction 100 3.4.2 The major classification units 100 3.4.3 Soil genesis aspects 103

3.5 Soil fertility aspects 104

3.6 Land management aspects 105

(iii) 4. SELECTED SOIL CHARACTERISTICS AND QUALITIES 106

5. AKNOWLEDGEMENTS 110

6. REFERENCES 111

LIST OF FIGURES Figure 1 : Location map and reconnaissance soil survey programme 2 Figure 2: Agro-Ecological Zone map 6 Figure 3: Geology (generalised) 9 Figure 4: Geomorphology map 14 Figure 5: Erosion susceptibility map 20 Figure 6: Soils (generalised) 28

LIST OF TABLES Table 1 : Rainfall data of several stations in the survey area (averages, 60% reliability) in mm 3 Table 2: Average annual potential evaporation in mm 4 Table 3: The temperature zones (after Braun in: Sombroek et al., 1982) ... 5 Table 4: Soil moisture availability zones (after Braun in: Sombroek et al., 19827 Table 5: The agro-climatic zones of some of the recording stations (after Braun in: Sombroek et al, 1982) 7

(iv) 1. THE ENVIRONMENT

1.1 Location, Communication and Population

The survey area is situated in the Eastern footslopes of Mt. Kenya covering parts of Embu, Meru and Kitui Districts of the Eastern Province. The survey area covers approximately 3063 Km2 i.e. 310, 000 ha. The area is bound by the Equator to the North, Latitude 0°.30'S to the South, Longitudes 37° 30'E to the West and 38° OO'E to the East as can be seen in Figure 1. The altitude rises from 490 m above sea level (a.s.l.) in the East to 3100 m to the West in the Mt. Kenya forest.

The road infrastructure comprises a tarmac road transecting through the middle of the survey area from Embu to Meru towns and a few all weather roads. Many of the all weather roads run from West to East following the pattern of ranges and the drainage system. There are two air strips both of which are in the northern part of the area. The highest population density is found in the central part of the area while the lowest is inthe Eastern part of the area. The area is inhibited by the Meru,Embu and the Kamba tribes as per the respective districts.

The area is well provided with schools shopping centres and medical centres except the eastern part where these facilities are far apart.

1 Fig.1 Location map and reconnaissance soil Drawing No. 97029 survey programme

2 1.2 Climate

1.2.1 Rainfall

The area is located at the windward side of Mt. Kenya and is characterised by large ainfall differences in average annual rainfall (see table 1 ). The rainfall gradient shows a strong east-west tendency due to differences in altitude and increases from the owlands towards Mt. Kenya to the West.

\A/ithin the survey area, the average annual rainfall ranges from 2208mm in the A/estern part to 544mm in the eastern part.

The distibution of the rainfall over the year is not equal, but bimodal in nature. The ong rains comes in March and May and the short rains from October to December. The distribution between the long rains is determined by the duration of the rainy season especially in the wetter areas. There is no significant difference in the amount af the rainfall during the first and second season.

In addition to average annual rainfall and its distribution during the year, the probability of rainfall is of great interest to agricultural production, especially in semi- arid regions which are characterized by small and variable amounts.

The annual rainfall exceeded in 6 out of 10 years (60% reliability), has been calculated for those stations having records of at least 10 years (60% reliability), has been calculated for those stations having records of at least 1 0 consecutive years. It should be remarked that, the variation in annual rainfall is relatively higher when the average annual rainfall is smaller (see table 1).

Also the rainfall intensities are higher in the dry eastern part of the area than in the moist western zones.

Table 1. Rainfall data of several stations in the survey area (averages, 60% reliability) in mm Station Alt. Vr J F M A M .1 J A S o N D Total • lwea, Mojwa (Mayna) 1158m 47 Av. 61 33 125 316 174 17 12 17 23 250 318 135 1479 "ath. Mission 60% 23 10 46 286 114 0 0 0 4 131 276 79 1220 N:kubu Sec. School 1527m 23 Av. 49 31 141 470 174 12 19 22 23 251 425 142 1765 60% 25 22 103 340 66 6 13 9 14 191 380 38 1525 »litunguu 1189m 19 Av." 21 24 149 305 142 9 7 10 9 213 374 137 1401 60% 6 1 67 206 50 0 0 1 3 94 294 14 1078 Marimba Centre 1844 m 26 Av. 75 72 187 469 236 18 18 21 35 34 511 221 2208 60% 45 49 101 398 189 17 5 13 17 272 394 104 1840 vlariene Coffee 1524m IS Av.» 62 77 157 398 184 22 13 20 27 361 443 154 1914 60% 17 28 69 316 84 10 9 10 16 170 294 80 1374 vtarimanti 610m 12 Av.2' 19 33 79 268 97 10 2 1 3 88 225 54 876 'huka County Council Farm 1492m 16 Av. 55 40 130 426 153 21 44 27 30 264 386 109 1685 60% 11 8 109 327 124 5 14 18 13 162 321 58 1170 Uinyenies D.O.'s office 1477m 8 Av. 25 42 128 410 170 29 43 38 24 225 269 66 1442

3 Chogoria forest station 1600m 11 Av. 62 54 160 518 237 36 41 33 43 278 390 158 2010 60% 12 43 75 528 203 25 25 29 27 216 385 100 1668 Ishiara, Embu 853m 11 Av. 31 31 87 268 45 8 3 3 11 81 221 68 857 60% 4 7 48 240 25 0 0 0 0 44 190 62 620 Chiokarige D.O.'s office 822m 11 Av. 36 29 103 251 50 15 0 3 6 115 222 105 935 60% 0 0 76 180 30 0 0 0 0 46 153 60 545 Mumbuni primary sch. 1096ra 9 Av. 51 31 105 385 108 9 3 6 28 204 318 102 1350 Kibugua Chiefs office 1467m 8 Av. 46 52 145 401 163 25 33 27 23 225 317 79 1536 Kama Mutonga 700m 15 Av. 19 17 95 133 31 3 1 0 4 64 125 52 544 60% 0 0 19 81 5 0 0 0 0 30 68 44 247 l) High figures because of unusually wet years

1.2.2. Potential evaporation Braun (Sombroek et al., 1982) calculated the average annual evaporation for Kenya according to the equation:

Eo = 2422 - 0.358h in which Eo = evaporation in mm and h = altitude in m (Woodhead, 1968). In the survey area the average annual potential evaporation varies from about 2204 mm at Marimanti to 1762 mm in the north-western part (see Table 2.). Compared to rainfall, the potential evaporation is fairly constant throughout the year at different sites, due to slight variations in temperature, air humidity and wind.

Table 2. Average annual potential evaporation in mm

Station Eo (mm) 9037011 Mwea Mujua Catholic Mission 2007 9037074 Nkubu secondary school 1875 9037085 Mutunguu 1996 9037102 Marimba Centre 1762 9037124 Mariene Coffee sub-centre 1876 9037160 Marimanti 2204 9037034 Chuka County Council farm 19 9037122 Runyenjes D.O.'s office 1900 9037123 Chogoria forest station 1850 9037161 Ishiara, Embu 2100 9037187 Chiokarige D. 0. ' s office 2150 9037198 Mumbuni primary school 2050 9037199 Kibugua Chief's centre 1900 9037232 Kama Mutonga 2150 source: Woodhead (1968)

4 1.2.3. Temperature

In general temperature is correlated with altitude. Therefore temperature shows a strong east- west tendency; warm parts in the lowlands in the eastern half of the area and cooler zones higher up near the mountain in the western part. To determine the temperatures in the area a specific relation was derived, according to Braun (unpub). The following relations between mean, mean maximum, mean minimum temperature (T) and altitude (h) were applied. Mean temperature (°C) T = 29.3 - 0.0066h (m) Mean maximum (°C) T = 35.0 - 0.0064h (m) Mean minimum (°C) T = 23.5 - 0.0068h (m)

Table 3. The temperature zones (after Braun in: Sombroek et al., 1982) me Mean temp.(°C) Mean max. (°C) Mean min. (°C) Climatic designation 24-29 30-35 18-24 fairly hot to very hot 22-24 28-30 16-18 warm 20-22 26-28 14-16 fairly warm 18-20 24-26 12-14 warm temperate 16-18 22-24 10-12 cool temperate 14-16 20-22 8-10 fairly cool

Throughout the year the temperature is quite constant (<4°C difference)as can be seen in table 3. The warmest period of the year is from January to March.

1.2.4. Agro-climatic zonation

For the determination of the agro-climatic zones in the area two approaches were used. The agro- climatic zonation is shown in figure 2. Firstly the agro-climatic classification of the Kenya Soil Survey (Sombroek et al., 1982) and secondly the agro-ecological classification of Jaetzold and Schmidt (1983).

Plant growth is mainly, affected by the balance between rainfall, evaporation and temperature. The agro-climatic classification is composed of moisture availability zones, based on the ratio of rainfall and evaporation (r/Eo), and temperature zones. Since the original classification was carried out on a small scale, the classification of the survey area is refined according to the same principle using additional data. The temperature zones are explained in paragraph 1.2.4. The criteria for the soil moisture availability zones can be found in Table 4.

5 37°30'E ')°00'S 0"0i

\

lengi

&

')°30'S L0°3C 37°30'E 38°00'E

10 KIlOMlTMi LEGEND

ZONE r/E% CLASSIFICATION KEY 8HH zone boundary I > 80 Humid II 65-80 Sub-humid III 50-65 Semi humid ill zone number IV 40-50 Semi humid lo semi arid ==. road V 25-40 Semi arid • o major town, others / .

6 Drawing No. 20002 Table 4. Soil moisture availability zones (after Braun in: Sombroek et al., 1982)

Zone r/Eo ratio Climatic designation [ >0.8 humid [I 0.65-0.8 sub-humid III 0.50-0.65 semi-humid [V 0.40-0.50 semi-humid to semi-arid V 0.25-0.40 semi -arid VI 0.15-0.25 arid VII <0.15 very arid

The entire area is covered by five soil moisture availability zones.

Table 5. The agro-climatic zones of some of the recording stations (after Braun in: Sombroek et al, 1982)

Station Agro-climatic zone soil moist, -temp. 9037034 Chuka County Council farm 1-4 9037122 Runyenjes D.O.'s office II-4 9037123 Chogoria forest station 1-4 9037161 Ishiara, Embu IV-2 9037187 Chiokarige D.O.'s office IV-2 9037198 Mumbuni primary school II-2 9037199 Kibugua chief's centre 1-2 9037232 Kama Mutonga V-l

7 The soil moisture availability zones are each sub-divided by two or three temperature zones. Hence, the area is characterized by succession of agro-climatic zones in east-west direction, varying from semi-arid (almost arid) to humid.

1.3 Geology and Geomorphology and Hydrology

1.3.1 Geology

The geology of the area consists mainly of volcanic and metamorphic rocks but recent superficial deposits occupy very small parts of the area. The geological survey of the area between the Embu and Meru (Schoeman, 1951) covers the area. A generalized geological map is shown in Figure 3. The major types of rocks in the area are described in this chapter. i) The Basement System Rocks

The Basement System rocks comprises mainly of Precambrian rocks which forms part of the Mozambiquean belt. These are sediments that have been metamorphosed, uplifted, folded, sheared and invaded by igneous intrusions. The rocks are of Katangan age and vary in the metamorphic facies. They occur extensively in the eastern part of the area and as inliers in the western part of the area. The igneous intrusion complex consists of ultramafic to subacid rocks. The ultramafic rocks are mainly gabbroic and comprises of hornblende gabbros, norites, tremolites and chromites. These occur in association with hypersthene bearing granulite. The subacid intrusions are smaller in size and comprises of diorites, granodiorites and quartzdiorites. These occur bedded in the rocks of the Basement System sensu-stricto. ii) Granitoids

These comprises of granites, granodiorites, gneisses and granitoid gneisses. The granites form large intrusive bodies accompanied by the granitoid gneisses in the surrounding areas. Many pegmitites and aplite veins cut through all the rocks of the Basement System. iii) Banded migmatic gneisses complex

This is a complex of mainly hornblende gneisses and biotite gneisses dissected by doleritic pegmatites and aplite veins. Some occur next to the gneisses and the migmatites. iv) Quartzite and muscovite schists

This is a small unit only found as part of the Basement system rocks in the southern most part of the area. They are less metamorphosed and occur as inliers in the volcanic area.

8 Î7M0E 38°00E O'OO'S

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Teng

0°30'S 37°30'E 38°00'E

}0 «ILOFIITMS

LEGEND 1 Phonolites (nepheline) [-••'-*-'"J Undifferentiated metamorphic rocks (mainly gneisses) KEY I ' V-v j Hornblende and biotile gneisses ..geological boundary gVWJ Grantoid gneisses and migmatites road |;'f-'/'.-'.] Basic rocks (basalts, gabbro, gabbro-nontes) major town, others l | Pyroclastic rocks (lahar complex tuffs and volcanic ashes) river ^H Various volcanic rocks (ashes,basalts,lahar etc) JSSyg Various rocks [js^fjifr] Granites

Fig. 3 Geology (generalised) Drawing No. 97028

9 v) The Volcanic rocks

The volcanic rocks in the area are related to the Rift Valley development. Mt. Kenya was built up contemporaneously with the Rift Valley during the Pliocene time. The multi center volcanism of the Nyambene range was also formed about the some time but the eruptions of the Mt Kenya stopped before that of the Nyambene ranges. The Mt. Kenya volcanism is dated from 3.5 to 2 million years while that of the Nyambene range is dated from 5 to 0.5 million years. These rocks occur in the western and the northern parts of the area, remnants of these rocks also occur as isolated small hills or plateaus in the eastern part of the area.

Three phases of deposition by theses volcanism can be distinguished. The first phase was during the main activity of Mt. Kenya. This phase took place during the Upper Pliocene time. In this period phonolite flows and lahars were deposited in the area. These forms the plateau level in the area which borders the Basement System area. The second phase was during the activity of the parasitic cones in the north eastern flanks of Mt Kenya. This was during the Plio-Pleistocene time. The lava flows during this time consisted of lahar and basalt. Mt Nyambene was most active during this time but there was no lahar flows in that area. Lahar flows are restricted in the Mt Kenya volcanism. The third phase was during the pleistocene time and is also related to the activity of the parasitic cones of Mt Kenya. Lahar, tuffs and volcanic ashes were deposited during the time especially in the river valleys.

Therefore the volcanic rocks related to the Mt. Kenya series are mainly lahars, phonolites, tuffs, basalt and ashes while those related to the Mt Nyambene series are basalt and ashes. vi) Superficial deposits

Sediments of superficial deposits occur in a few areas in the north eastern part of the area. These are deposited in old basins and forms rather flat landforms. They consist of coarse gravels chiefly from rocks of Mt Nyambene volcanism with subordinate Basement System rocks.

The following rocks and/or rock groups are recognised as the parent material of the soils in the area:

Q predominantly granitoid gneisses and migmatites G granites and granitic gneisses F gneisses rich in Fe-Mg minerals, mainly hornblende and biotite gneisses U undifferentiated Basement System rocks B gabbros norites and basalt I phonolites P pyroclastics, mainly lahar complex, tuffs and volcanic ashes V various volcanic rocks X various undifferentiated rocks, and colluvium mixed with alluvium

The lithology of the rocks found in the area is not very well documented. However the lithology of the rocks found in the area is described below:

10 Quartzite

This is medium to fine grained, low grade metamorphic rock. It consists of mainly quartz grains and resembles a single band of sand in the Precambrian sedimentary series.

Granitoid gneisses

These are composed of fine grained quartz and pinkish white feldspars with no preferred orientation. Parallel streaks of well oriented micas are scattered in the rock.

Migmatites

The migmatites tend to form rock outcrops and tors with smoothly Weathered surfaces and spheroidal boulders. They consists bands mainly of amphibolitic composition alternating with light bands consisting of quartz and plagioclase. The rock has medium to fine grains and are strongly folded.

Augen gneisses

These consist of medium to coarse grained quartz and feldspars with more or less oriented hornblende and biotite. Phenocrysts of feldspars are scattered in the rocks.

Granulates

The granulates have fine grains and are dark grey in colour.They consist of hypersthene, pyroxene, biotite, plagioclase and quartz in almost equal proportions.

Granites

Granites are coarse grained and have granitic texture. They consist of quartz and feldspars which are pink in colour. Some have white feldspars and hornblende.

Gneissose granites

These resemble the granites in composition and texture but contain some micas which are oriented.

Hornblende and biotite gneisses

The hornblende gneisses are relatively soft and are easily weathered. They are rounded, bluish green in colour, fine textured and consists of hornblende, plagioclase and quartz. The biotite gneisses are similar to the hornblende gneisses but contain a high proportion of biotite.

11 Talc tremolite

These contain also chrolite. They are soft, silky and irregularly weathered rocks with greenish colour. They are fine to medium grained and consists of quartz, chrolite and micas.

Diorites and granodiorites

These are few in occurrence. The weathered surfaces are brown to dark brown in colour. They consist of feldspars and quartz and are medium grained with large feldsphathic phenocrysts.

Peridotites

These are brown to black in color and are medium grained. They consist of olivine and feldspars as the dominant minerals.

Gabbros

These are greenish blue to black in colour and consists of predominantly hornblende crystals. They are medium grained and quite resistant to weathering.

Basalt

Two types of basalt occur in the area. These are the Mt. Kenya basalt and the Mt Nyambene basalt. They all have columnar structure and are dark grey in colour. They have a few phenocrysts which are greenish brown in colour and up to 2 mm in diameter. The rocks re vesicular and those of Mt. Nyambene series have vesicles which are filled with zeolites and other iron oxides.

Phonolites

These are dark bluish black in colour and with many small phenocrysts. The groundmass is very dense and fine grained. They consist of plagioaclase sanidine and large phenocrysts of nepheline.

Lahar complex

These are referred to as Kenyite in the geological report of the area and are a complex of pyroclastic material. They can be divided into loose-porous and dense-firm lahars.The latter has an appearance of lava flows and forms outcrops with rounded appearance. The former have a mud flow appearance and are unstable when saturated with water.They show a large variation in composition and hence are called here lahar complex. The groundmass is usually dark grey to brownish grey in colour and is fine grained in texture. They contain angular to rounded fragments of other rock types such as basalt, phonolite and trachyte ranging from a few millimeters to a few meters in diameter.

12 Tuff

These occur along the river valleys and some former valleys. They are medium grained and light coloured. They are soft and stratified indicating deposition in a lacustrine condition.

Volcanic ashes

These are brown to yellowish brown in colour and unconsolidated. The weathered surface is yellowish red. They consist of mainly volcanic glass and a few very light minerals, hence the rock is very light. The origin of the ashes is not very clear but in view of its situation near the Mt. Nyambene most of them may be from the Nyambene volcanism.

1.3.2 Geomorphology

The geomorphology of the area is closely related to the geology and the geological history of the area. This is a bisection which comprises of the Volcanic and the Basement System landscapes. For the purpose of soil mapping, the land forms have been described in terms of major land form units according to Kenya soil survey (van de Weg, 1978). The following major land form units are distinguished in the area as can be figure 4:. - Mountains (M) - Hills and minor scarps (H) - Footridges (R) - Footslopes (F) - Plateaus (L) - Uplands (U) - Plains (P) - Valleys (V) - Bottomlands (B)

/

13 J8°00'L ,1 III •

Tpng

0°30S 37'30'E 38°00'E

n KILOMITMS

LEGEND r^ ^~i Mountains ' 1'relief intensity over 300m; slopes over 30%)

Y • YHill s and minor scarps (relief intensity 100 - 300m; slopes 8 - 30%) KEY geomorphology boundary f-oot Ridges (relief intensity 10 - 200m; slopes 5 - 30%) road major town, others [.Y.Y.^Footslopes river (relief intensity less than 100m; slopes over 10%)

^Plateaus •^(relief intensity less than 50m; slopes 0 - 8%)

Uplands (reli.ef intensity less than 50m; slopes 0 - 16%)

IPIams (relief intensity less than 10m; slopes 0 - 2%)

ÄJValleys ''v (relief intensity 50 - 100m; slopes 8 - 30%

IBottomlands (reliet intensity less than 10m; slopes less than 2%) Mountains

The mountains are the highest parts in the area especially in the Basement System area. They have a relief intensity of more than 300 m and slopes are generally more than 30%. These include; Kijege, Ntugi, Kiagu, Mumoni, Kiera and Njuguni mountain. Most of them consist of Basement System rocks except Njuguni which consists of gabbro-norites. The mountains of the Basement System rocks are characterized by extremely rocky surfaces and irregular slopes while that of the basic rocks have regular slopes. Most of the mountains are in the eastern part of the area which is predominantly covered by the rocks of the Basement System. They are erosional in origin except a few which are igneous intrusive.

Hills and Minor Scarps

The Hills are also high lying land forms with relief intensity of 100 to 300 m and slopes of over 16%. They occur throughout the area but are more frequent in the eastern part of the area. Most of them consist either of Basement System rocks or ultrabasic to basic intrusive. In the western part of the area the hills are mainly inliers of Basement system rocks in the volcanic flows. The hills of the igneous rocks such as Marine, Nkarine and Ntua have steep and regular slopes while those of the Basement System rocks have irregular slopes.

Scarps are few in the area and form the lower end of the Mt. Kenya volcanic series. Therefore they consist of rocks of the Mt. Kenya volcanic series underlain by the Basement System rocks, which are exposed in some places. The scarp is interrupted by deep river valleys in some places.

Footridges

These are land forms of variable relief intensity but not less than 50m. The slopes range from 4 to 35%. They are characterized by long convex ridges (interfluves) and many V shaped river valleys. The interfluves are more or less parallel to one another. These occur in the western part of the area and consist of exclusively volcanic rocks of Mt kenya series. Three levels of the footridges are distinguished in the area on the basis of altitude and relief intensity.

The highest level is refereed to as the Mt Kenya Forest Footbridge Level(Rl).This is at altitudes higher than 2000 m and is entirely in the Mount Kenya Forest. The relief intensity is more than 80 m and the dominant slopes are sometimes as high as 35%. The area consists of kenyite in the south and basalt in the north according to Schoeman (1951). However the whole area is strongly influenced by volcanic ashes which are well exposed especially in the northern area.

The second level of the footridges is referred to as the Kionyo Level Footbridge (R2). This lies between 1600 and 2000 m above sea level and has relief intensity higher than 50 m. The dominant slopes are 16% but may be as high as 45% where there is major dissections of the river valleys. The interfluves are relatively narrow in width especially in the middle and the southern part of the unit.It is situated around Kionyo and Kithirune in the north, Mutindwa and

15 Kiangua in the central part and part of Mt Kenya forest in the south. The area consists of basalt and pyroclastic rocks in the north while in the south lahar complex are predominant. The central part is covered by ashes tuff and phonolite.

The third level of the footridges is referred to as the Chogoria Level Footbridge (R3). This lies between 1200 to 1700 m ASL and has relief intensity which is higher than 50 m. The dominant slopes are 10 to 16% but may be as high as 35% at the sides of the valleys. The interfluves are relatively flat and wide while the valleys are steep and V shaped. This occupies the area around Nkubu, Chogoria, Chuka and Runyejes. Most of it is on the western side of the Thuci-Nkubu road, which forms more or less the lower boundary of the unit except in the southern part where the boundary is further to the east of the road. The area is covered by basalt in the extreme north, phonolites in the middle and lahar complex in the southern. Tuffs occur along the river valleys and inliers of the rocks of the Basement System occur as hills.

Footslopes

The footslopes occur at the foots of the mountains, hills and the scarps. They have slopes of 6 to 25% and relief intensity ranging from 50 to 100m. Debris from the hills, mountains or scarps may accumulate in the footslopes. They are usually relatively narrow belts and consist of detritus and debris derived from the rocks of the surrounding landform. However where the debris does not accumulate the rocks are of the underlying geological formation.

Plateaus

The plateaus are rather flat table like landforms with a scarp at least on one of the sides. The relief intensity is less than 20 m in most of the cases and the dominant slopes are less than 5 %. The plateaus form the end of the Mt. Kenya volcanic lows in this area. They therefore consist of basalt, tuff and lahar complex. They are deeply dissected by the many rivers which flow in the area.

Uplands

The uplands are formed by processes of peneplaination and erosion. The relief intensity is less than 100 m and slopes are less than 16%. They are dissected by river valleys which in some places are narrow and shallow while in other places they are shallow wide and flat at the bottom. Two levels of uplands are distinguished in the area.

The High Level uplands (Ul) occurs in the central part of the area extending from near Runyenjes to north of Nkubu markets. It lies between 900 and 1400 m ASL and consists of predominantly rocks of the Mt. Kenya volcanic series which are basalt, tuffs phonolite and lahar complex. However at the extreme east of the unit rocks of the Basement System are exposed especially where the river valleys have cut deep enough.

16 The Low Level uplands (U2) occupies the eastern part of the area. It extends from Ishiara to Marimanti and around Chiokarige market. It lies at altitudes less than 1000 m ASL and consists of predominantly the Basement System rocks. However in the north rocks of Mt Nyambene volcanic series, mainly basalt form inliers as thin capping on the Basement System, rocks. The area has undergone several periods of strong erosion and peneplanation as evidenced by stone- lines and some buried layers.

Plains

These are flat land forms with relief intensity of less than 10m and slopes of less than 5%. In this area, the plains occur extensively in the area which is influenced by the basalt of Mt Nyambene series, around Nkondi, Mitunguu and Gaitu areas.

Major and Minor River Valleys

River valleys are narrow elongated landforms, formed by the erosion of the rivers. They may be U Or V shaped but in this area they are mainly V shaped. They occur all over the area but are more common in the western part of the area. In the eastern part of the area , most of them are too small in width to be separated.

The Major river valleys are formed by the major rivers in the area. They have a relief intensity of more than 50 m and the slopes of the valleys sides is more than 25 %. They have a width of more than 100 m in most places. The minor and more common river valleys have a relief intensity of less than 50 m, slopes of less than 25 % at the valley sides and width of less than 100 m in most places.

Bottomlands and Sinkholes

These are relatively flat land forms forming depressions without prominent outlets. They occur as swamps at either the beginning of the streams or completely enclosed depressions. In some places sinkhole like landforms also occur in the area. These land forms consists of mainly colluvium and alluvium materials derived from the rocks in the vicinity.

1.3.3 Hydrology

1.3.3.1 Surface water

The Chuka - Nkubu area is situated in the upper-Tana catchment basin. The drainage system is very dendritic beginning from Mount Kenya and the footslope of Mount Kenya. The Tana river traverses the south eastern part of the area forming the boundary between the Embu and the Kitui Districts. The drainage system is determined by the radial drainage pattern of Mount Kenya which is drained by many major deeply incised perennial rivers.

The Ena, Tungu, Rugutti, Mara, Kithinu and Mariara rivers originate from the footslopes of the Mount Kenya while Mutonga, Nithi, Thuchi, Thingithu and Kathita originatefrom the partly glaciated part of Mount Kenya. All these rivers drain into the Tana river in or near the survey

17 area. There are also some intermittent streams such as the Konyu and the Kalange which are in Kitui District.

These perennial rivers form the main supply of the water needs in the area. The water may be contaminated by the human activities especially down stream and may not be very suitable for domestic use. However the water is suitable for irrigation as is demonstrated by some irrigation schemes in the area. The Waters of the Thuchi river is used for a small irrigation scheme at Ishiara while that of Thingithu river is used for an irrigation scheme at Mitunguu. There are other very small irrigation units in the area especially on the western part of the area where there are many rivers, streams and springs.

1.3.3.2 Ground water

The southern half of the area was surveyed for ground water in 1985 (Veldkamp and Visser, 1986) and some drilling for ground water was done in 1986 especially in the eastern part of the area. The occurrence of ground water-bodies in the rocks is determined by the fractures of the rocks. Thus the higher the amount of fractures in the rocks the higher the chance of occurrence of groundwater in the rocks. In the Basement System area the regoliths are in general too thin to contain large aquifers. However there are possibilities of finding reasonable amounts of groundwater in some of the Basement System rocks especially near the dry river beds.

In the Volcanic area there are possibilities of finding large aquifers especially in the lahar complex area. This is because the lahar complex is thick and has a high intensity of fractures which favor formation of aquifers. However in the areas with thin lava flows such as the basalt and the phonolites, there are no possibilities of finding large aquifers because these flows are relatively thin.

Some of the fluviatile deposits also found along the valleys of the major rivers and dry river beds offer good opportunities of occurrence of groundwater.

1.3.4 Soil erosion

Soil erosion may be grouped according to the main agent which are mainly wind and water. In this area only soil erosion by water is significant and hence soil erosion by wind is not considered. Soil erosion by water depends on the following interactive factors (Hudson, 1971; Morgan 1979):

- erosivity -the tendency of the eroding agent to cause erosion

- erodibility - susceptibility of soil to detachment and transport

- slope and slope length

- soil cover

18 - conservation and management practices

Erosion can occur as superficial splash, sheet (inter-rill), rill or as deep gully erosion. Splash and sheet erosion are easily obliterated by tillage. In some soils a certain amount of soil loss will not affect crop production in the soil and is called permissible soil loss. Besides erosion there are related processes which cause deterioration of soil for sustained production such as soil compaction, crust formation, salinization removal of soluble nutrients by leaching, fixation of nutrients etc. The term soil degradation is used to describe all these processes.

The present erosion hazard in the survey area was observed during the field work and classified as very slight, slight, moderate, severe and very severe (see Figure 5) . The susceptibility for loss of soil by erosion in the survey area was estimated by combining the effects of the land characteristics related to climate (erosivity), soil (erodibility) relief and the soil cover.

19 37°30'E 38°00'E 0°00'S

Teog

0°30'S 37°30'E

LEGEND

I |Very slight hazard

fc-'SJI Slight hazard

^^^M Moderale hazard

HHHJ Severe hazard

|.'!vXvl Severe hazard to very severe hazard

|:::;::;::;:l:;:;:;;l Very severe hazard

Fig.5 Erosion susceptibility map Drawing No. 97022

20 Factors of soil erosion

Rainfall erosivity

Only rainfall erosivity will be discussed as wind erosivity is not important in the area. Erosivity depends on the rainfall intensity, duration and the frequency of the rainstorms. In the survey area, the erosivity of the rainstorms decrease with the altitude as the rainfall also decrease with the altitude. The highest rainfall intensities were recorded in the eastern part of the area where intensities of up to 90 mm/hr were recorded.

Soil erodibility

The susceptibility of soil to detachment and the subsequent transport by the rain splash and run off is called soil erodibility. This is determined by many factors such as soil stability, infiltration rate, soil texture, grade and size of the structure. The least erodible soils in the area are the deep red Nitisols which are intensively used for tea cultivation. The most erodible soils are the chromic Luvisols which are used in shifting cultivation. These also show the lowest infiltration rates which is caused by the very strong surface sealing and crusting. The highest steady infiltration rates are also found with the Nitisols which are under coffee plantation.

Topography

Erosion increases with the increased slope-steepness and slope length as a result of enhanced velocity and volume of surface run off. Running water is however often slowed down by obstacles such as edges of stones. Therefore in this area high amount of surface stoniness reduces the effect of slope and slope length.

Vegetation

It is generally accepted that the effect of vegetation cover is the strongest in reducing or stopping altogether erosion in a given area. The major role of vegetation is interception of rain drops. Their energy is reduced by the plant rather than pass to the soil. In addition, vegetation reduces the velocity of the surface run off and the biological activity association with the vegetation provides good porosity, hence increases the infiltration capacity of the soil.

21 2. METHODS

2.1 Soil survey methods 2.1.1 Office methods

Before the field work all the aerial photographs, topographic and geological maps, reports and other literature about the area were collected and studied. The area is covered by the topographic maps from the Survey of Kenya at the scale of 1:50 000 sheets 122/1,2,3 and 4 which are Nkubu, Mitunguu, Chuka and Ishiara respectively. Aerial photos of the survey area at a scale of 1:50,000 were obtained and interpreted using a pair of stereoscope. A photo-interpretation map was made for the whole area which was used to plan the field work. Most of the aerial photographs were for 1963 and 67. All the photographs were obtained from the survey of Kenya. In sheets 122/3 and 4,which cover the southern part of the survey sample areas were selected for which aerial photographs at the scale of 1:25,000 were used. A geological map at the scale of 1:250,000 was used to indicate the geology of the area.

2.1.2 Field methods

A general inventory of geology, physiography and soils on the basis of aerial photographs, exploratory soil map and the geological report was made for the area. This was used to select the sample areas in the southern sheets. Over 2,000 routine augerings were made with the Edelman soil auger, up to 120 cm deep or to a hindering layer (auger hole observations). These were located randomly (free survey) throughout the survey area and were recorded in the Kenya soil survey auger hole observation standard forms. They were then located either on the aerial photographs or the field maps or both. Soil mapping units were then delineated on the basis of the observation and notes made during the traversing of the area. About 204 profile pits were made in the whole area. Each soil mapping unit was represented by at least one or more profile pit except where the units were inaccessible. The profile pits were made up to 1.5 and augered up to 2 m or to the bedrock. The profile pits were described and recorded in the standard Kenya soil Survey profile description forms and sampled per horizon for laboratory analysis. Samples for soil fertility analysis were taken around the profile pit to a depth of about 30 cm.

Undisturbed samples (core samples) were taken from selected representative profiles for bulk density and water holding capacity (pF) analysis. Undisturbed samples were also taken from selected profiles pits for micromorphological investigations. Infiltration measurements were taken around a few selected profile pits to give and indication of the infiltration rate and percolation

2.1.3 Laboratory methods

Most determinations for soil characterization (soil survey) were done at the National Agricultural Research Laboratories in Nairobi (NARL). The procedures are summarized below. A few soil samples were analyzed at the TPIP laboratory in Chuka and a few were analyzed at the Department of Soil Science and Geology in the Agricultural University of Wageningen (AUW).

22 Unless where otherwise stated, most analyses were done in NARL summarized below:

Texture

Treat mechanically to remove cementing agents; shake overnight with sodium hexametaphosphate and sodium carbonate in end-over-end shaker. Measure silt and clay (<0.05 mm) with a hydrometer after 40 s and clay (< 0.002 mm) after 6.4 hours. The difference represents the sand fraction. pH and electrical conductivity (EC)

For soils with an electrical conductivity > 120 mS at 25° C, prepare a saturated paste extract for measurement of pH (paste) and EC. Measure pH (H20) in a soil-water suspension and pH (KCl) in a suspension of soil in aqueous KCl (concentration of 1 mol/1 of volume ratio 1:2.5)

Mass fraction of carbon

Walkley and Black method (Black, 1965).No correction factor was used to compensate for recovery.

Mass fraction of nitrogen

Semi-micro kjeldahl on the A horizon only (Black 1965.).

Exchangeable cations

Leach soil with ammonium acetate ( concentration, 1 mol/1) of pH 7. Estimate Na and K by the emission spectrometry and addition of lanthanum chloride for Ca and Mg. Estimate Mg and Ca by Atomic absorption spectrometry.

Cation-exchange capacity

After leaching out exchangeable cations, wash the soil with aqueous ethanol (volume fraction 0.95) and percolate with acidified NaCl. Steam distill off the ammonia and titrate against HCl (concentration 10 mmol/1) ( Houba et al ,1979).

Exchangeable acidity

Extract soil with BaC12 (concentration 300 mmo/1), not buffered at any pH and titrate with 0.05 mol/1 NaoH (Mehlich et al., 1960)

Mass fraction of the nutrients

Soak for one hour with acid (concentration of HCl 100 mmo/1 and of H2S04 12.5 mmol/1) in

23 a volume ratio 1:5 and shake for 10 min. Estimate Ca, K and Na in the extract by emission spectrometry after anion resin treatment to counteract precipitation of Ca-salts. Estimate Mg by visible spectrometry with thizol yellow, P with vanadomolybdophosphoric yellow, and Mn with phosphoric acid and potassium periodate (Mehlich et al., I960).

Bulk density (volume mass)

Dry a known volume of soil core at 105 °C and weigh (Richards, 1954)

Moisture tension - TPIP/NARL. Estimate mass fraction of moisture in saturated soil and soil equilibration with sandbox to pF .4, 1.0, 1.5 and 2.0 and kaolin box for pF 2.3, 2.7, 3.0, 3.7 and 4.2 (Stakman et al., 1969)

Micromorphology

Dry the undisturbed sample at 105° C for a fortnight and impregnated with polyester resin. Saw the sample to 0.02mm and cover with glass cover. Examine the sample under microscope for micromorphological features.

2.1.4 Cartographic methods

For the survey area a base map as required at a scale of 1:100,000 was not available. To overcome this problem use was made of four adjoining 1:50,000 sheets as supplied by the Survey of Kenya, which together cover the same area. Each of these four sheets was simplified by deleting all unwanted details. Subsequently each sheet underwent a photographic reduction to the final 1:100,000 scale after which the four sheets were joined together to serve as a film positive.

New elements, not featuring on the original 1:50,000 sheets, such as recently constructed roads, schools, etc. were added. This additional information was collected during the fieldwork and is presented under responsibility of the KSS.

The soil map was litho printed in subsequent steps, using six litho plates. Each plate was used to print one different colour. The colours employed were black, deep blue, brown, yellow, magenta and cyan. The black plate was for all topographic details, soil boundaries, symbols, the legend and other marginal information. The blue one was for the hydrographie information while the brown one was for the contour lines. An additional black plate was required to provide information on symbols for hills, soil depth classes, etc.

After preparation of all seven plates, a proof print of the coloured soil map was produced using a "Cromlin" proofing machine. The map was finally printed in The Netherlands on an offset printing machine.

24 3. SOILS

3.1 Previous work

Gethin-Jones and Scott (1959), prepared a soil map of Kenya at the scale of 1:3,000,000.

The soils described in the map which are in the survey area are:

- Stony brown loams from pyroclastic rocks - Red friable clays with or without humic topsoil from pyroclastic and volcanic rocks. - Red friable clays (latosolic soils) from volcanic and Basement System rocks - complex of yellow brown loam, very pale brown mottled loamy sands and darkbrown loams from various rocks. - Very shallow to shallow rocky soils from igneous intrusions and rocks of the basement System.

These correspond with various units recognised during the survey but the actual correlation can not be determined due to the different approaches.

Kenya soil survey prepared the Exploratory Soil Map of Kenya at the scale of 1:1,000,000 (Sombroek et al., 1982). The soil mapping units described in this map correlate with the units described in this soil survey. However some differences are observed due to the differences in the scale of the soil surveys. The units described by Sombroek (1982) are:

M2 - Andosols Rl - Nitisols and Andosols R2 - Nitisol R3 - Nitisols, Acrisols and Cambisols L2 - Nitisols F13 and F16 - Luvisols and Ferralsols L17 - Ironstone and Lithosols

Large scale soil surveys covering small areas have been carried out in the area. These include: Mitunguu area (van der Pouw et al., 1972 and Gachene et al., 1987).

3.2 General soil properties

The soils in the area are strongly influenced by the climate, physiography and parent material. An east-west trend is observed for all these factors, giving rise to a east-west climo-sequence. The soils in the Mt. Kenya forest footridges (Rl) and some parts of the Kionyo Level Footridges, which is strongly influenced by the volcanic ashes are well drained, moderately deep to deep, dark brown, friable silt loam to loam. The clay mineralogy is predominantly allophane, halloysite and kaolinite. These soils are generally deficient in plant nutrients and have high soil

25 reaction due to strong leaching.

The soils of the Mountains (M), Hills and Minor scarps (H) which have mainly migmatite, granitoid gneisses and gabbro-norites are excessively drained to well drained, shallow, dark reddish brown to dark brown, rocky and stony, friable clay loam to clay. They vary very much in most soil properties but the most limiting factors for agricultural use are soil depth, rockiness, stoniness and the steepness of the slopes.

Soils of the Kionyo (R2) and the Chogoria (R3) level footridges which consists of mainly consolidated pyroclastic rocks (lahar complex), phonolite and basalt are well drained, very deep, dark red to dark reddish brown, friable clay. The clay increase in the soil profile is generally gradual and the clay minerals are predominantly kaolinites, illite and some halloysite. These soils are generally deficient in plant nutrients but have rather favourable physical properties for plant growth.

Soils of the High Level (Ul) uplands and some parts of the plateaus (L) are developed on mainly consolidated pyroclastic rocks, some phonolite and basalt. The soils are well drained deep to moderately deep, dark red to dark reddish brown, friable to firm clay. The soils are generally low in plant nutrients but have rather favourable physical properties for plant growth.

The soils of the lower level uplands (U2) are developed from various Basement System rocks. They vary very much in characteristics. However the most predominant ones are well drained, moderately deep to deep, dark red, friable clay loam to clay. They are rich in most plant nutrients except nitrogen and some places phosphorous but have rather unfavorable physical properties.

Other soil occurring in the low level uplands (U2) are well drained, shallow to moderately deep, dark reddish brown, friable clay loam to clay. The area is rocky and stony in the surface and the soil chemical and physical properties vary widely. Soil depth is the most limiting factor in most of the areas for most crops.

The soils of the plains (P) in the northern part of the area and some parts of the plateaus (L) in the southern part of the are well drained, deep, red to dark reddish brown, friable clay. The northern part has predominantly basalt of Mt. Nyambene Series while the southern part has consolidated pyroclastic rocks. Clay minerals are predominantly kaolinite and illite. The soils are generally deficient in plant nutrients but have rather favourable physically properties.

In the lower parts of the plains and the plateaus, the soils are well drained, shallow to moderately deep, dark reddish brown to dark brown, friable, gravelly clay to clay loam. They have pisoferric or petroferric material within 30 to 100 cm depth. In some places they are rocky and stony. The subsoil is gravely and the clay minerals are mainly kaolinite and illite. They are generally well supplied with the plant nutrients but the soil depth and some physical properties are not favourable for plant growth.

26 The soil of the bottomlands (B) and some river valleys (V) are developed on colluvium and alluvium material. They are imperfectly drained to poorly drained, moderately deep to very deep, very dark greyish brown to black clay. In some places the soils are cracking and firm while in other places they show hydromorphic properties up to the surface. The subsoil is generally calcarious and the clay minerals are mostly montmollironite. They are generally rich in plant nutrients but the drainage conditions are not favourable for growth of most crops (see fig 6).

27 38°00'E 0°00'S

'MÊM

• •''///;>C' '''>''/,' />'// /'/^

Tengil

''//,1 ;>v

ff(tf 5 JÏ 'VVj r:K H''

0°30'S 37°30'E 38°00'E

10 KIlOfltTRIS

LEGEND KEY Excessively drained to well drained ,shallow to deep.dark red to brown, fairly rocky and stony soils of varying texture and consistence. soil boundary (LITHOSOIS.CAMBISOLS.RECOSOLS and ACRISOLS) road

y/ ,'A Well drained,deep to very deep.red to dark brown,friable clay with 20- • o major town, others l' ' ''•' cm humic top soil. (ANDOSOLS.NITOSOIS and PHAEOZEMS) .—•£- — river

Excessively to moderately well drained, moderately deep to very deep, dusky red to dark reddish brown, friable, slightly rocky and slightly stony, sandy clay loam to clay. (ACRISOLS, LUVISOLS and FERRAISOLS) I Imperfectly drained to poorly drained, shallow to very deep, very dark greyish brown to black, mottled, firm, calcareous clay loam to cracking clay; in places stratified, (VERTISOLS, FLUVISOLS, CIEYSOIS and ACRISOLS)

Fig. 6 Soils (generalised) Drawing No. 97023

28 3.3 Description of the soil mapping units

3.3.1 Systematics and nomenclature

The codes used in the legend are based on physiography, parent material and soil characteristics systematically. The physiographic units range from the mountains which have very high slopes and relief intensity to the bottomlands which have very low slopes and relief intensity. The parent material ranges from volcanic ashes of Tertiary age to the Basement System rocks of Precambrian age. The soil characteristics used in this soil survey are depth to bedrock or limiting material, colour and drainage conditions. Each soil description is followed by the soil name of the FAO-Unesco nomenclature. A slope class symbol is also indicated in each mapping unit except in the mountains, hills and the minor scarps. Arabic numerals (1,2,...) are used for the further subdivision of each entry of physiographic unit and also soil mapping unit with all other entries the same but differing in soil characteristic. Small letters (n) and (d) are used in the subdivision of the plateaus and the plains to indicate non-dissected and dissected respectively. The letters are used in the soil mapping unit symbol:

Physiography

M - Mountains H - Hills and minor scarps R - Mountain footridges F - Footslopes L - Plateaus U - Uplands P - Plains V - Major and minor valleys B - Bottomlands

29 Geology (parent material)

Q - Migmatites, migmatised granites and granitoid gneisses G - Granites F - Rocks rich in ferro-magnesium minerals U - Undifferentiated Basement System rocks B - Gabbros, gabbro-norites and basalt I - Phonolites P - Pyroclastic rocks ( Tuffs, lahar complex and volcanic ashes) V - various volcanic rocks X - various rocks

Soil characteristics Depth:

P - Shallow p - Moderately deep Colour: b - Brown colours d - Dark colours r - Red colours Drainage class: g - Gleyic (showing hydromorphic properties within 50 cm depth.

Other characteristics:

C - Complex of soils A - Association of soils

Slope classes (%)

A - 0-2 flat to very gently undulating B - 2-5 gently undulating C - 5-8 undulating D - 8-16 rolling E - 16-30 hilly F - > 30 mountainous

Most of the terms used in the description of the soils especially in the legend are based on the FAO-Unesco (1974). All the colors were described by Munsell Scheme (Munshell colour co., 1970). The colours mentioned in the mapping unit description are for the moist soil conditions unless otherwise stated.

30 3.3.2 Soils of the mountains

Unit MQC Total area 10720ha Parent material Granitoid gneisses and Migmatites Macro relief Mountainous (slopes classes E and F) Surface stoniness/ Extremely stony to stony and extremely rocky to rocky rockiness and boulderly Vegetation/Land use Forest to wooded bushland (vegetation species unidentifi­ ed); extensive grazing and charcoal burning. Soils general Complex of somewhat excessively drained to well drained, reddish brown to brown; soils of varying depth, consistence, rockiness, stoniness and texture with AC or ABC horizon sequence. Colour A- horizon is dark yellowish brown(10YR3/4) to dark brown (7.5YR3/4). B- horizon is reddish brown(5YR4/3) to brown(7.5YR5/4). Texture Gravelly sand to sandy clay loam throughout. Structure Moderate to weak, medium, subangular blocky throughout. Consistence Loose to friable when moist, slightly sticky to non sticky and plastic to non plastic when wet throughout.

Chemical properties The pH-H20 is 6.1 - 6.8 and the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.6 in the topsoil and 0.4 in the B- horizon. The CEC-soil varies from 3.8 to 6.0 me/100g. The base saturation is more than 50% in the topsoil and the subsoil Soil classification FAO - Unesco LEPTOSOL, eutric REGOSOLS, eutric CAMBISOLS and orthic LUVISOLS; partly lithic and stony phases, USDA lithic EUSTROPEPTS and udic HALPLUSTALFS.

31 Unit MBP Total area 1640ha Parent material Ultramafic and mafic gabbros and gabbro norites. Macro relief Mountains (slope classes E and F) Surface stoniness/rockiness Stony and rocky Vegetation/land use Wooded bushland (Boscia mossambicensis, Combretum molle, Piliostigma thoningii); forest reserve, extensive grazing and charcoal burning. Soils general Somewhat excessively drained, shallow to moderately deep, dark reddish brown to brown, friable,rocky and stony sandy clay loam to clay loam, with AC or ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/2). B/C- horizon is dark reddish brown (5YR3/4) to brown (7.5YR5/4) Texture Sandy loam to clay loam throughout. Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout. Soil classification1 FAO-Unesco eutric REGOSOLS and LEPTOSOLS; partly lithic and stony phases. USDA lithic EUSTROPEPTS. Remarks The unit consists of about 15 % rock out crops and boulders

* The classification is inferred.

Representative profile Appendix 3 profile No 1.

'The soils classification has been derived from the description a road cut which was not sampled 32 3.3.3 Soils of the hills

Unit HQC Total area 710ha Parent material Granitoid gneisses, migmaties and migmatised granites Macro relief Hilly and steeply dissected (slope classes D, E and F Surface stoniness/rockiness Fairly stony to extremely stony and rocky Vegetation/land use Wooded bushland (vegetation species unidentified); extensive grazing and in places shifting cultivation of millet and sorghum

Soils general Complex of somewhat excessively drained, dark reddish brown, friable soils of varying depth, consistence, stoniness, rockiness and texture with AC or ABC horizon sequence Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (7.5YR 3/4) . B- horizon is dark reddish brown (5 YR3/4) to strong brown (7.5YR5/6) Texture Sand to sandy clay loam in A and B- horizons; silt/clay ratio is 0.3 - 0.8 Structure A- horizon is single grains and weak, medium, granular. B- horizon is moderate, medium, subangular blocky. Consistence Loose to friable when moist, slightly sticky to non sticky and slightly plastic to non plastic when wet.

Chemical properties The pH-H20 is 6.4 - 7.5 and the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.9 in the topsoil and 0.1 in the B- horizon. The CEC-soil varies from 10.3 to 12.9 me/100g. The base saturation is more than 50% in the topsoil and the subsoil Soil classification FAO - Unesco LEPTOSOL, eutric REGOSOLS, eutric CAMBISOLS and chromic LUVISOLS; partly lithic and stony phases, USDA lithic EUSTROPEPTS and udic HALPLUSTALFS. Remarks 20% of the unit consists of rock outcrops and boulders, severe gully and rill erosion can be observed in the areas where the vegetation has been cleared

Representative soil profile (s) Appendix 3 profile No. 2

33 Unit HGP Total area 1160ha Parent Material Granites Macro relief Hilly (slope classes D, E and F) Surface stoniness/ Fairly stony and rocky rockiness Vegetation/landuse Wooded bushland to woodlands (Grevillea robusta, Erythrina abyssinica,); permanent cultivation of coffee, maize, beans,sorghum etc. and dairy zero grazing

Soils, general Well drained, shallow to moderately deep, red to dark reddish brown, friable, clay loam to clay;in places rocky and fairly stony, with ABC horizon sequence.

Colour A- horozon is yellowish red (5YR4/6) to dark reddish brown (5YR3/4). B- horizon is red (2.5YR4/6) to dark reddish brown (5YR4/4). Texture Clay ; silt/clay ratio is 0.25 - 0.35. Structure Moderate, fine to medium angular blocky throughout. Consistence friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet.

Remarks Severe gully and rill erosion is observed along the roads and the footpaths.

Representative soil profile Appendix 3 profile No. 3

34 Unit HUC Total area 346ha Parent material Various metamorphic Basement System rocks Macro relief Hilly (slope classes D, E and F) Surface stoniness/rockiness Fairly stony and rocky Vegetation/landuse Wooded bushland (vegetation species unidentified); extensive grazing and in a few places shifting cultivation of millet and sorghum Soils, General Complex of well drained, dark reddish brown to brown, gravelly soils varying depth, consistence, stoniness, rockiness and texture with AC or ABC horizon sequence Colour A- horizon is dark brown (7.5YR 3/4) to dark yellowish brown (10YR3/4). B- horizon is dark reddish brown (5 YR3/4) to strong brown (7.5YR5/6) Texture Sand to sandy clay loam throughout the profile. Structure Weak to moderate, fine subangular blocky or massive throughout. Consistence Loose to friable when moist, slightly sticky to non sticky and slightly plastic to non plastic when wet throughout the profile. Chemical properties The pH-HzO is 7.4 and the EC us less than 0.1 mmhos/cm. Organic carbon percentage is 0.7 on the topsoil. The CEC- soil is 8 me/100gthroughout. The base saturation is more than 90% in the topsoil and the subsoil except in a few places where it is less than 40%. Soil classification FAO - Unesco LITHOSOL, eutric REGOSOLS, and eutric and dystric CAMBISOLS and chromic LUVISOLS; partly lithic and stony phases. USDA lithic USTORTHENTS, typic USTROPEPTS and ustic DYSTROPEPTS. Remarks 10% of the unit consists of rock outcrops and boulders. severe gully and rill erosion can be observed where the vegetation has been cleared. Representative soil profile Appendix 3 profile No. 4

35 Unit HBP1 Total area 1629ha Parent material Gabbros, norites and basalt. Macro relief Hilly to rolling (slope classes D, E and F) Surface stoniness/rockness Fairly stony and rocky Vegetation/landuse Wooded bushland (vegetation species unidentified); fores reserve and extensive grazing Soils, general somewhat excessively drained to well drained, shallow, dark red to dark reddish brown, rocky and stony, sandy clay loam to clay loam with AC or ABC horizon sequence Colour A- horizon is dark reddish brown (5YR3/4). B- horizon, dark red (2.5YR3/6) to dark reddish brown (5YR3/4) Texture Sandy clay loam to clay loam; silt/clay ratio is 0.3 - 0.6 Structure Weak to moderate, fine to medium, subangular blocky throughout. Consistence Friable when moist, sticky and slightly plastic when wet. Remarks 10% of the unit consists of rock outcrops and boulders. Representative soil profile none

36 Unit HBP2 Total area 809ha Parent material Basalt of Mt Kenya series. Macro relief Hilly (slope classes E and F). Surface stoniness/rockiness In places rocky and stony. Vegetation/landuse Wooded bushland and forest (vegetation species unidentified); partly forest reserve. Soils, general Well drained, shallow to moderately deep, dark yellowish brown, friable, clay loam to clay; in places fairly rocky and stony, with AC or ABC horizon sequence. Colour A- horizon is dark brown (10YR3/4). B- horizon is yellowish red (5YR4/6). Texture Clay loam to clay througout the profile Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout.

37 Unit HBC Total area 4253ha Parent material Gabbros and gabbro-norites. Macro relief Hilly to rolling (slope classes D, E and F). Surface stoniness/rockiness Stony to fairly stony and rocky to fairly rocky. Vegetation/landuse Wooded bushland (vegetation species unidentified); forest reserve and extensive grazing. Soils, general complex of somewhat excessively drained, shallow to moderately deep, dark reddish brown to dark brown gravely soils of varying consistence, rockiness, stoniness and texture with AC or ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/4). B- horizon is dark reddish brown (5YR3/4) Texture A- horizon is sandy clay loam to clay and B- horizon clay loam to clay. Silt/clay ratio is 0.3 - 0.8 Structure Weak, fine to medium, subangular blocky throughout. consistence Friable when moist, sticky and slightly plastic wet.

Chemical properties The pH-H20 is 7.9 in the topsoil and 7.5 - 8.1 in the B horizon. The EC is less than 0.1 mmhos/cm and the organic carbon percentage 0.7 in the topsoil and 0.49 to 0.22 in the subsoil. CEC-soil is 14.3 me/100g in the topsoil and 18.8 - 15.2 in the B- horizon and the base saturation varies from 25 % in the topsoil and 14 -25 % in the subsoil. Soil classification FAO - Unesco humic ACRISOLS and dystric CAMBISOLS, partly stony phase USDA typic TROPOHUMULTS and typic DYSTROPEPTS. Representative soil profile Appendix 3 profile No. 5

38 Unit HIP Total area 1160ha Parent material Nepheline phonolite Macro relief Rolling to hilly (slope classes D, E, and F). Surface stoniness/rockness Slightly stony and slightly rocky Vegetation/landuse Wooded bushland to bushland and partly forest {Ocotea usambarensis, Podocarpus milianjianus, Neobutonea macrocalyx); timber and permanent cultivation of tea, maize, potatoes and daily zero grazing. Soils, general Well drained, moderately deep to deep, red to dark reddish brown, friable, sandy clay loam to clay; in places fairly rocky and stony, with ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/2) to dark brown (7.5YR3/4). B- horizon is red (2.5YR4/6) to dark reddish brown (5YR4/3). Texture A- horizon is sandy clay loam to clay and B-horizon is clay loam to clay; silt/clay ratio ranges from 0.33 - 0.76. Structure Moderate, medium, subangular blocky throughout. consistence Friable when moist, sticky and plastic when wet throughout.

Chemical properties The pH-H20 is 5.5 in the topsoil and 5.5 - 5.7 in the B horizon. The EC is less than 0.1 mmhos/cm and the organic carbon percentage is 2.86 in the topsoil and 1.96 to 0.61 in the subsoil. CEC-soil is 29.7 me/100g in the topsoil and 11.3 - 28.7 in the B- horizon. Base saturation varies from 36% in the topsoil and 18 -38% in the subsoil. Soil classification FAO - Unesco humic ACRISOLS and dystric CAMBISOLS, partly stony phase USDA typic TROPOHUMULTS and typic DYSTROPEPTS.

Representative soil profile Appendix 3 profile No.6

39 Unit HPC Total area 290ha Parent material Consolidated lahar complex. Macro relief Rolling to hilly (slope classes D, E, and F). Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Wooded bushland to bushland (Ocotea usambarensis, Strombosia schefleri ); permanent cultivation of tea, maize,bananas, potatoes and daily zero grazing. Soils, general Complex of well drained moderately deep to deep, dark red to brown, friable clay soils of varying rockiness and stoniness; with ABC horizon sequence. Colour A- horizon is dark reddish brown(5YR/4) to dark brown (7.5YR3/4). B- horizon is dark red (5YR4/6) to dark brown (7.5YR3/4). Texture Clay throughout; silt/clay ratio ranges from 0.2 to 0.4. Structure Moderate to strong, fine to coarse, subangular blocky throughout. consistence Friable to firm when moist, sticky and plastic when wet throughout. Representative profile none

Unit HVP Total area 2180ha Parent material various volcanic rocks. Macro relief Hilly (slopes (E and F) Surface stoniness/rockiness Very stony and rocky Vegetation/landuse Dense bushland to wooded bushland (Combretum molle Acacia brevispica Acacia polyacantha Phyllanthus somalensis); extensive grazing. Soils, general Well drained, shallow, dark reddish brown, fairly rocky and very stony, gravelly, clay loam to clay; with AC or ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (10YR4/3) and B- horizon is dark reddish brown (5YR3/4). Texture Gravelly clay loam to clay throughout. Structure Weak, fine to medium, subangular blocky throughout. consistence Friable when moist, slightly sticky and slightly plastic when wet. Remarks About 10% of the unit consists of rock outcrops and boulders. Gully and rill erosion is evident along the roads and where the vegetation has been cleared. Representative soil profile none

40 3.3.4 Soils of the footridges

Unit R1PC Total area 9120ha Parent material Lahar complex (predominantly tuff and volcanic asses). Macro relief Rolling to hilly (slope classes D, E and F). Vegetation/landuse Dense forest (Ocotea usambarensis, Podocarpus milianjianus, Neobutonea macrocalyx Hagenia abbysinica Fagaropsis angolensis) forest reserve and timber cutting. Soils, general complex of well drained,deep to very deep, yellowish brown to brown, friable, silty clay loam to clay; partly smeary, with ABC horizon sequence.

Colour A- horizon is brown (7.5YR5/4) to dark brown (10YR3/4). B- horizon is brown (7.5YR5/4) to dark yellowish brown (10YR4/6). Texture A- horizon is silty clay loam to clay loam and B- horizon is silt clay loam to clay. Structure Weak, medium, angular blocky and strong to moderate, fine, subangular blocky throughout. consistence Friable when moist, slightly sticky and slightly plastic when wet throughout.

Chemical properties The pH H20 is 4.2 - 5.4 in the topsoil and 4.7 - 5.5 in the B- horizon while the EC is less than 0.1 mmhos/cm. The organic carbon percentage 3.92in the topsoil and 2.11 to 1.14 in the subsoil. CEC-soil is 29 me/100g in the topsoil and ranges from 27 - 25.7 me/100g in the B- horizon. The base saturation is 11.2% in the topsoil and in the subsoil is from 9.5 to 6.0%. Halloysite, allophane and illite are the dominant clay minerals. Soil classification FAO - Unesco dystrie and ando-cumulic NITISOLS, humic ANDOSOLS and humic CAMBISOLS. USD A typic PALEUDULTS, hydric DYSTRANDEPTS and typic HUMITROPEPTS. Representative soil profile Appendix 3 profile No. 7

41 Unit R1VP Total area 10947ha Parent material Various volcanic rocks. Macro relief Rolling to hilly (slope classes C, D and E). Vegetation/landuse Dense forest (Ocotea usambarensis, Podocarpus milianjianus, Neobutonia macrocalyx Hagenia abbysinica fagaropsis angotensis);forest reserve and timber cutting Soils, general Well drained, moderately deep to deep, dark yellowish brown to brown, friable silty loam to clay loam partly smeary; with 20 - 30 cm of acid humic topsoil, and with ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/2) and B- horizon is brown (7.5YR5/4) to dark yellowish brown (10YR4/4) . Texture A-horizon is loam to clay loam and B- horizon is silt loam to loam; silt/clay ratio ranges is 1.5 - 4.7. Structure A- horizon is weak, medium crumbs and B-horizon is weak, fine to medium, subangular blocky. Consistence Friable when moist, slightly sticky and slightly plastic when wet; in places smeary.

Chemical properties The pH-H20 is 5.4 in the topsoil and 5.5 in the B- horizon while the EC is less than 0.1 mmhos/cm. The organic carbon percentage is 4.78 in the topsoil and 4.34 - 3.07 in the subsoil. CEC-soil is 25.2 me/100g in the topsoil while 26.6 me/100g in the subsoil. The base saturation is about 15% in the topsoil and 22% in the subsoil. Halloysite, allophane and illite are the dominant clay minerals. Soil classification FAO - Unesco humic ANDOSOLS and humic CAMBISOLS. USDA hydric DYSTRANDEPTS and typic HUMITROPEPTS.

Representative soil profile Appendix 3 profile No. 8

42 Jnit R2Prl Total area 20630ha 'arent material Lahar complex (volcanic ash and tuff) vlacro relief Rolling to hilly (slope classes C, D and F). /egetation/landuse Partly forest (vegetation species same as unit RIVp) partly wooded bushland to bushland (Acacia meanisii, Juniperus procera, Grevillea robusta); permanent cultivation of tea, coffee, maize, beans, potatoes etc and daily zero grazing. soils, general Well drained, very deep, dark red to dark reddish brown, friable, clay with 20 - 30 cm humic topsoil, shiny ped faces and ABC horizon sequence. "olour A- horizon is dark reddish brown (5YR3/2) to dark brown (7.5YR3/3) and B- horizon is dark red (2.5YR3/6) to dark reddish brown (5YR3/4). Texture Clay throughout; silt/clay ratio ranges from 0.06 to 0.25. Structure A- horizon is moderate, medium to coarse subangular blocky and B- horizon is strong, medium angular and subangular blocky. Consistence Friable when moist sticky and plastic when wet throughout. Chemical properties The pH-H20 is 4.5 increasing with depth and the EC is less than 0.1 mmhos/cm. The organic carbon percentage is 4.32 in the topsoil and 3.51to 1.11 in the subsoil. CEC-soil is 33.6 me/100g in the topsoil and between 31.7 to 26.7 me/100g in the B- horizon. The base saturation 5 % in the topsoil and between 9 and 6% in the subsoil. Kaolinite, illite and halloysite are the dominant clay minerals. 5oil classification FAO - Unesco mollic and humic NITISOLS. USDA typic PALEUDOLLS and typic PALEUDULT. Representative soil profile Appendix 3 profile No. 9 Remarks Most of the unit is intensively cultivated and some of the topsoil chemical properties may vary from time to time.

43 Unit R2Pr2 Total area 1250ha Parent material Lahar complex (consolidate pyroclastic rocks). Macro relief Rolling to hilly (slope classes C, D and E). Vegetation/landuse Wooded bushland to bushland (Acacia mearnsii, Juniperus procera, Grevillea robusta); permanent cultivation of tea, coffee, maize, beans, potatoes, vegetable, bananas etc and dairy zero grazing. Soils, general Well drained, deep to very deep, dark red to dark reddish brown, friable clay with 20 - 30 cm humic topsoil, shiny ped faces and ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/4) and B- horizon is dark red (2.5YR3/6) to dark reddish brown (5YR3/4). Texture Clay throughout; silt/clay ratio is 0.4 - 0.8. Structure Strong, medium to coarse, subangular and angular blocky. consistence Friable when moist, sticky and plastic when wet throughout. Representative soil profile none Remarks Most of the unit is intensively cultivated

44 Unit R2Pb Total area 5114ha Parent material Volcanic ashes and tufs overlying phonolite at about2 m. Macro relief Undulating to hill (slope classes, B, C, D and E). Vegetation/landuse Partly forest (vegetation species same as unit RIVp) partly wooded bushland to bushland (Acacia meanrsii, Juniperus procera, Grevillea robusta); permanent cultivation of tea, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, deep to very deep, yellowish red to dark brown, friable and smeary silt loam to clay loam with 20 - 30 cm acid humic topsoil and ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/4) and B- horizon, yellowish red (5YR4/6) to dark brown (7.5YR3/2). Texture Silt loam to clay loam throughout. Structure Weak, fine subangular blocky and moderate, fine angular blocky. Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout. Chemical properties The pH-H20 is 5.2 in the topsoil and 5.1 - 5.9 in the subsoil while the EC is less than 0.2 mmhos/cm. Organic carbon percentage is 4.58 in the topsoil and 3.74 - 0.34 in the B- horizon. CEC-soil is 18.7 me/100g in the topsoil and 17.5 - 12.7 me/100g in the B- horizon. The base saturation is 21 % in the topsoil and ranges from 32 to 11 % in the B- horizon. The dominant clay minerals are allophane, halloysite, kaolinite and illite. Soil classification FAO - Unesco humic ANDOS0LS USDA hydric DYSTRANDEPTS

Representative soil profile Appendix 3 profile NO. 10

Remarks Part of this unit is in the Mt. Kenya forest while part of it is under continuous cultivation.

45 Unit R2Pbp Total area 1880ha Parent Material Volcanic ashes and tuffs overlying phonolite at about 0.5 - 6 m. Macro relief Undulating to hilly (slope classes, B, C, D and E). Vegetation/landuse Partly forest (vegetation species same as unit RIVp) partly wooded bushland to bushland (Acaciameanrsii, Juniperus procera, Grevillea robusta); permanent cultivation of tea, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, moderately deep to deep, dark yellowish brown to dark brown, friable, silt loam to clay loam; in places smeary, with 20 - 30 cm acid humic topsoil and ABC horizon sequence. Colour A- horizon is dark brown, (10YR3/4) and B- horizon, dark brown (7.5YR3/4) to dark yellowish brown (10YR4/4) . Texture A- horizon is silt loam to loam and B- horizon is silt loam to clay loam. Structure A- horizon is massive and B- horizon is weak, fine to medium, subangular blocky. consistence Friable when moist, sightly sticky and slightly plastic when wet throughout; in places smeary. Chemical properties The pH-H20 is 5.5 in the topsoil and 5.9 to 5.6 in the subsoil while the EC is less than 0.2 mmhos/cm. organic carbon percentage is 3.71 in the topsoil and 2.96-0.94 in the B- horizon. CEC-soil is 8.9 me/100g in the topsoil and 13.7-5.1 in the subsoil. The base saturation is 67% in the topsoil and 22-17% in the susoil.The bulk density ranges from 0.8 to 0.96g/cm2. The dominant clay minerals are allophane, halloysite, kaolinite and illite. Soil classification FAO - Unesco humic ANDOS0LS and humic CAMBISOLS, partly lithic phase. USDA hydric DYSTRANDEPTS and typic HUMITROPEPTS.

Representative soil profile Appendix 3 profile NO. 11

Remarks About 5% of the unit consists of rock outcrops and boulders.

46 Unit R2Vr Total area 2700ha Parent material Various volcanic rocks. Macro relief Undulating to hilly (slope classes B, C, D and F) Vegetation/landuse Wooded bushland to bushland (Acacia meanrsii, Juniperus procera, Grevillea robusta); permanent cultivation of coffee, tea, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, deep to very deep, red to dark reddish brown, friable to firm clay with shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/3) and B- horizon is red (2.5YR4/6) to dark reddish brown (5YR3/2). Texture Clay in the topsoil and subsoil Structure A- horizon is strong, fine to medium subangular blocky. B- horizon is strong, medium subangular and angular blocky. Consistence Friable to firm when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.2 in the topsoil and ranges from 5.1 tO 5.0 in the subsoil and the EC is less than 0.1 mmhos/cm in the topsoil and subsoil. Organic carbon percentage is 2.69 in the topsoil and 1.13 - 1.7 in the B horizon. CEC-soil is me/100g in the topsoil and me/100g in the b-horizon the subsoil The base saturation ranges from 9-52% decreasing with depth. The dominant clay minerals are kaolinite, halloysite and illite. Soil classification FAO - Unesco humic and dystric NITISOLS USDA typic PALEUDULTS

Representative soil profile Appendix 3 profile No. 12

Remarks Some of the chemical properties in the topsoil may vary due to intensive cultivation and use of fertilizers.

47 Unit R3Br Total area 3270ha Parent material Basalt of Mt. Kenya series. Macro relief Undulating to rolling (slope classes B, C and D) Vegetation/landuse Wooded bushland woodlands (Erythrina abbysinica, Cordia abbysinica, Grevillea robusta; Croton macrostachyus) permanent cultivation of coffee, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, very deep, red to dark reddish brown, friable to firm clay with 20 cm of humic topsoil, shiny ped faces and ABC horizon sequence.

Colour A- horizon is dark reddish brown (5YR3/3) to dark brown (7.5YR3/4) and B- horizon is red (2.5YR4/6) to dark reddish brown (5YR3/4). Texture Clay in the topsoil and subsoil Structure A- horizon is weak, coarse, crumbs and strong, medium, subangular blocky and B- horizon is strong, medium, subangular and moderate to strong, medium, angular blocky. Consistence Friable to firm when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.1 in the topsoil and 5.1 to 4.8 in the subsoil while the EC is less than 0.1 mmhos/cm in the topsoil and the subsoil. Organic carbon percentage is 2.66 in the topsoil and between 1.69 and 0.73 in the subsoil. CEC-soil is 28.7 me/100g in the topsoil and 25.0 - 23 me/100g in the subsoil. The base saturation is 29% in the A- horizon ranges from 29 to 21% in the B-horizon. The dominant clay minerals are kaolinite but some halloysite and illite may occur. Soil classification FAO - Unesco humic NITISOLS USDA typic PALEUDULTS

Representative soil profile Appendix 3 profile No. 13

Remarks Some of the chemical properties in the topsoil may vary due to intensive cultivation and use of fertilizers.

48 Unit R3Ir Total area 2240ha Parent material Nepheline phonolites. Macro relief Undulating to rolling (slope classes B, C and D) Vegetation/landuse Wooded bushland woodlands {Erythrina abbysinica, Cordia abbysinica, Grevillea robusta; Croton macrostachyus) permanent cultivation of coffee, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, very deep, red to dark reddish brown, friable to firm, clay with 20 cm of humic top soil, shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/3) while B horizon is red (2.5YR4/6) to dark reddish brown (5YR3/4). Texture Clay in the topsoil and subsoil Structure A- horizon is strong, medium to coarse subangular blocky. B- horizon is strong coarse, subangular and strong, medium, angular blocky. consistence Friable to firm when moist, sticky and plastic when wet. Chemical properties The pH-H20 is 4.5 in the A- horizon and between 5.0 and 4.3 in the B-horizon while the EC is less than 0.1 mmhos/cm in the topsoil and the subsoil. Organic carbon percentage ranges from 2.01 to 0.64 decreasing regularly with depth. CEC-soil is 22.0 me/100g in the topsoil and 13.2 - 15.5 me/100g in the subsoil. The base saturation is 11% in the A- horizon and between 18 and 8% in the B- horizon. The dominant clay minerals are kaolinite but some halloysite and illite may occur. Soil classification FAO - Unesco humic NITISOLS USDA typic PALEUDULTS

Representative soil profile Appendix 3 profile No. 14

Remarks Some of the chemical properties in the topsoil may vary due to intensive cultivation and use of fertilizers.

49 Unit R3IP Total area 740ha Parent material Nepheline phonolites. Surface stoniness/rockiness Stony and fairly rocky. Macro relief Undulating (slope classes B and C) Vegetation/ landuse Same as unit R3Ir Soils, general Well drained, shallow to moderately deep, dark reddish brown, gravelly clay in places rocky and stony, with ABC horizon sequence. Colour Dark reddish brown (5YR3/4) to dark brown (7.5YR3/4) in the subsoil and the topsoil. Texture Gravelly clay in the subsoil and the topsoil. Structure Weak to moderate, medium, subangular blocky in the topsoil and strong, medium, subangular to angular blocky in the subsoil. .onsistence Friable when moist, sticky and plastic when wet in the topsoil and the subsoil. Chemical properties The pH-H20 is 5.8 in the topsoil and ranges6.2 to 5.9 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 2.35 in the A- horizon and between 1.94 and 1.51 in the B-horizon. CEC-soil is 27.5 me/100g in the topsoil and 26.2 - 25.6 me/100g in the subsoil. The base saturation is 31% in the A- horizon and between 31 and 29% in the B-horizon. The dominant clay minerals are kaolinite but some halloysite and illite may occur. Soil classification FAO - Unesco humic CAMBISOLS, partly lithic and stony phases and LITHOSOLS. USDA typic and lithic DYSTROPEPTS.

Representative soil profile Appendix 3 profile No. 15

Remarks About 10% of the units consists of rock out crops and boulders.

50 Unit R3Prl Total area 27040ha Parent material Consolidated pyroclastic rocks. Macro relief Undulating to rolling (slope classes B, C and D) Vegetation/landuse Wooded bushland woodlands (Erythrina abbysinica, Cordia abbysinica, Grevillea robusta; Croton macrostachyus) permanent cultivation of coffee, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, very deep, red to dark reddish brown, friable clay with humic topsoil of varying depth, shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/2 - 3/4) and B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Clay in the topsoil and subsoil. Structure Moderate, strong, medium subangular and angular blocky in the topsoil and strong, medium, subangular to angular blocky in the subsoil. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 4.3 in the topsoil and ranges 4.7 to 4.5 in the B- horizon while the EC is less than 0.2 mmhos/cm. Organic carbon percentage is 1.79 in the A- horizon and between 1.21 and 0.8 in the B-horizon. CEC- soil is 18.2 me/100g in the topsoil and 21.5 - 14.7 me/100g in the subsoil. The base saturation is 12% in the A- horizon and between 18 and 14% in the B-horizon. The dominant clay minerals are kaolinite but some halloysite and illite may occur.

Soil classification FAO - Unesco humic NITISOLS USDA typic PALEUDULTS

Representative soil profile Appendix 3 Profile No. 16

51 Unit R3Pr2 Total area 640ha Parent material Consolidated pyroclastic rocks. Macro relief Undulating to rolling (slope classes B, C and D) Vegetation/landuse Wooded bushland woodlands (Erythrina abbysinica, Cordia abbysinica, Grevillea robusta; Croton macrostachyus) permanent cultivation of coffee, maize, vegetables, potatoes etc and dairy zero grazing. Soils, general Well drained, deep to very deep, dark reddish brown, friable clay with shiny ped faces, ABC horizon sequence and in places 20 cm humic topsoil. Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (7.5YR3/4).B- horizon is dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Clay in the topsoil and subsoil. Structure A- horizon is weak, medium subangular blocky and strong, medium, crumbs. B- horizon is moderate to strong, medium, subangular and angular blocky. Consistence Friable when moist, sticky and plastic when wet throughout. Representative profile: none

52 3.3.5 Soils of the footslopes

Unit FUP Total area 2750ha Parent material Various Basement System metamorphic rocks. Macro relief Rolling (slope classes C and D) Surface stoniness/rockiness In places stony and rocky. Vegetation/landuse Wooded bushland to bushland thicket (Acacia tortilis, Commiphora africana, Acacia brevispica, Acacia mellifera, Acacia nilotica); shifting cultivation of sorghum, millet, cotton, green gram etc and extensive grazing.

Soils, general Well drained, shallow to moderately deep, red to dark reddish brown, friable, sandy loam to sandy clay loam with ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/2) to dark greyish brown (10YR3/1) and B-horizon is red (2.5YR4/8) to dark reddish brown (5YR3/4). Texture Sandy loam to sandy clay loam in the topsoil and subsoil. Structure Weak, fine to medium, subangular blocky throughout. Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout. Representative soil profile none Remarks About 15 % of the unit consists of rock outcrops and boulders.

53 Unit FVP Total area 320ha Parent material Various volcanic rocks Macro relief Rolling (slope classes C and D). Surface stoniness/rockiness In places very stony and fairly rocky Vegetation/landuse Wooded bushland (Combretum molle, Acacia polyacantha, Phyllanthus somalensis); shifting cultivation of sorghum, millet, pigeon peas, sunflower, cotton, green grams etc and extensive grazing. Soils, general Well drained, moderately deep to deep, reddish brown, friable, clay loam to clay in places rocky and stony, with ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/2) and B- horizon, reddish brown (7.5YR3/3). Texture Clay loam to clay throughout. Consistence Friable when moist, slightly stick and slightly plastic when wet throughout.

Chemical properties The pH-H20 is 6.2 in the topsoil and ranges 6.8 to 6.3 in the B- horizon while the EC is less than 0.2 mmhos/cm. Organic carbon percentage is 1.17 in the A- horizon and between 0.91 and 0.8 in the B-horizon. CEC- soil is 21.6 me/100g in the topsoil and 18.6- 17 me/100g in the subsoil. The base saturation is 67.96% in the A- horizon and between 68.8 and 83% in the B-horizon.

Soil classification FAO - Unesco eutric REGOSOLS and chromic CAMBISOLS, partly stony phase. USDA lithic and eutric EUSTROPEPTS.

Representative soil profile Appendix 3 profile No. 17

54 Unit FXC Total area 2870ha Parent material Various rocks Macro relief Rolling (slope classes C and D). Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Same as in unit FUP.

Soils, general Complex of: -Somewhat excessively drained, shallow to moderately deep, dark red to dark reddish brown, friable sandy clay loam in places rocky and stony; with AC or ABC horizon sequence. -Somewhat excessively drained, shallow, dark red to dark reddish brown, friable clay loam to clay; with ABC horizon sequence. -Well drained, moderately deep to deep, very dark brown, friable to firm clay; in places slightly rocky and slightly stony with ABC horizon sequence. Colour Dark red (2.5YR3/6) to dark reddish brown (5YR3/4) throughout in two of the components and very dark brown (10YR3/2) in the other component of the complex. Texture Sandy clay loam to sandy clay throughout in two of the components and clay in the other component of the complex Structure Moderate, fine to medium, subangular blocky throughout in all the components of the complex. Consistence Friable to firm when moist, slightly sticky to sticky and slightly plastic when wet in all the components of the complex.

Representative soil profile none

55 3.3.6 Soils of the plateaus

Unit LnIC Total area 390ha Parent material Nepheline phonolites. Macro relief Flat to gently undulating (slope class 0 to 2 %) Surface stoniness/rockiness In places slightly stony to very stony and slightly rocky to very rocky. Vegetation/landuse Wooded bushland (Acacia tortilis, Combretum molle, Acacia polyacantha); shifting cultivation of maize, cotton, sunflower, tobacco, pigeon peas, beans, etc and extensive grazing. Soils, general Complex of well drained, dark reddish brown, friable, very gravelly, sandy clay loam to sandy clay soils of varying depth, and stoniness with AC or ABC horizon sequence. Colour A- horizon dark brown (7.5YR3/4) and B- horizon dark reddish brown (5YR3/4). Texture A- horizon is silt clay to sandy clay and B-horizon gravelly sandy clay loam. Structure Fine, medium, subangular blocky throughout. Consistence Friable when moist, slightly sticky and slightly plastic when wet Remarks About 20% of the unit consists of rock out crops and boulders

Representative soil profile none

56 Unit LnPr Total area 5219ha Parent material Consolidated pyroclastic rocks (lahar complex). Macro relief Flat to gently undulating (slope classes 0 to 2 %) Vegetation/landuse Wooded bushland (Acacia tortilis, Combretum molle, Acacia polyacantha Terminalia £rowra/);permanent cultivation of maize, cotton , sunflower, tobacco, pigeon peas, beans, etc and semi-extensive grazing. Soils, general Well drained to moderately well drained, very deep, dark reddish brown, friable clay with ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (7.5YR3/4) and B- horizon is dark red (2.5YR3/6) to dark reddish brown ((5YR3/4). Texture Clay throughout. Structure Moderate, medium to coarse subangular blocky throughout. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.7 in the topsoil and ranges 6.2 to 5.7 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 2.08 in the A- horizon and between 1.32 and 0.52 in the B-horizon. CEC- soil is 27.7 me/100g in the topsoil and 24- 14.8 me/100g in the subsoil. The base saturation is 23.7% in the A- horizon and between 21.8 and 12.9% in the B-horizon. Soil classification FAO - Unesco humic ACRISOLS. USD A : ustic PALEHUMULTS.

Representative soil profile : Appendix 3 profile No. 18

57 Unit LnPC Total area 1340ha Parent material Consolidated pyroclastic rocks (lahar complex). Macro relief Flat to gently undulating (slope classes 0 to 2 %)). Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Wooded bushland (Acacia tortilis, Combretum molle, Acacia polyacantha Terminalia brownii); permanent cultivation of maize, cotton , sunflower, tobacco, pigeon peas, beans, etc and semi-extensive grazing. Soils, general Complex of excessively well drained, dark reddish brown to brown,very gravelly sandy clay loam to sandy clay soil of varying depth, rockiness, stoniness and consistence with AC or ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/4) and B- horizon dark reddish brown ((5YR3/4) to brown (7.5YR5/4). Texture Very gravelly sandy clay loam to sandy clay throughout the topsoil and the subsoil. Structure Moderate, fine to medium subangular blocky throughout. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout. Chemical properties The pH-H20 is 5.8 in the topsoil and ranges 5.9 to 5.3 in the B- horizon while the EC is less than 0.2 mmhos/cm. Organic carbon percentage is 1.35 in the A- horizon and between 0.73 and 0.47 in the B-horizon. CEC- soil is 23.2 me/100g in the topsoil and 14- 7.9 me/100g in the subsoil. The base saturation is 23% in the A- horizon and between 12 and 3% in the B- horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco dystric CAMBISOLS, pisoferric and partly lithic phases and LEPTOSOLS. USDA plinthic and lithic DYSTROPEPTS.

Representative soil profile Appendix 3 profile No. 19

58 Unit LdBr Total area 1590ha Parent material Basalt of Mt. Kenya series. Macro relief Flat (slopes 0-2%) Vegetation/landuse Wooded bushland to woodlands (Grevillea robusta, Cordia abysinica, Croton macrostarchys); continuous cultivation of coffee, bananas, sunflower, cotton, pigeon peas, etc and semi-extensive grazing. Soils, general Well drained, very deep, dark reddish brown, very friable clay with shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR 2.5/2) and B- horizon is dark reddish brown (5YR 3/3). Texture Clay throughout. Structure A- horizon is weak, coarse, subangular blocky and B- horizon is moderate, coarse, angular blocky. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.4 in the topsoil and ranges 5.8 to 5.5 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.84 in the A- horizon and between 0.81 and 0.21 in the B-horizon. CEC- soil is 24.6 me/100g in the topsoil and 25.4-22.8 me/100g in the subsoil. The base saturation is 24% in the A- horizon and between 25 and 20% in the B-horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco humic NITISOLS USDA ustic PALEUSTALF

Representative soil profile Appendix 3 profile No. 20

59 Unit LdVr Total area 2400ha Parent material Various volcanic rocks. Macro relief Flat to gently undulating (slope classes A and B). Vegetation/landuse Wooded bushland (Acacia tortilis, Combretum molle, Acacia polyacantha Terminalia ); permanent cultivation of maize, cotton, sunflower, tobacco, pigeon peas, beans, etc and semi-extensive grazing. Soils, general Well drained, deep to very deep, dark reddish brown, friable to firm, clay with shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (7.5YR3/2)and B-horizon is dark reddish brown ((5YR3/4).

Texture Clay throughout the topsoil and the subsoil. Structure A- horizon is weak, coarse, subangular blocky and B- horizon is moderate to strong, subangular and angular blocky. Consistence Friable to firm when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.5 in the topsoil and ranges 5.8 to 5.5 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.95 in the A- horizon and between 0.86 and 0.30 in the B-horizon. CEC- soil is 21.5 me/100g in the topsoil and 21- 18 me/100g in the subsoil. The base saturation is 14% in the A- horizon and between 33 and 20% in the B- horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco umbric NITISOLS and luvic PHAEOZEMS. USDA ustic PALEUSTALF and udic ARGIUSTOLL

Representative soil profile Appendix 3 profile No. 21

60 3.3.7 Soils of the uplands

Unit UlBr Total area 1580ha Parent material Basalt of Mt Kenya series. Macro relief Gently undulating to undulating (slope classes A, B and C). Vegetation/landuse Wooded bushland to woodlands (Grevillea robusta, Cordia abyssinica, Croton macrostachyus); continuous cultivation of coffee, bananas, sunflower, cotton, pigeon peas, etc and semi-extensive grazing. Soils, general well drained, very deep, yellowish red to dark brown, friable to firm clay with shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/2) to dark brown (7.5YR3/2) and B- horizon is yellowish red (5YR4/6) to dark brown (7.5YR3/4). Texture Clay throughout, silt/clay ratio is 0.1. Structure A- horizon is weak, moderate, subangular blocky and B- horizon strong, medium .angular blocky. Consistence friable to firm when moist, sticky and plastic when wet throughout. Chemical properties The pH-HzO is 6.7 in the topsoil and ranges 6 to 5.9 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.95 in the A- horizon and between 0.98 and 0.23 in the B-horizon. CEC- soil is 33.3 me/100g in the topsoil and 28.6-23.3 me/100g in the subsoil. The base saturation is 45.6% in the A- horizon and between 41.2 and 32.2% in the B-horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco mollic NITISOLS and luvic PHAEOZEMS

USDA typic PALEUDOLL.

Representative soil profile Appendix 3 profile No. 22

61 Unit Ullr Total area 2230ha Parent material Nepheline phonolites. Macro relief Gently undulating to undulating (slope classes A, B and C). Vegetation/ landuse Wooded bushland to woodlands {Grevillea robusta, Cordia abyssinica, Croton macraytac/iyw.s); cultivation of coffee, bananas, sunflower, cotton, pigeon peas, etc and semi- extensive grazing. Soils, general Well drained, very deep,dark red to dark reddish brown, friable to firm clay with shiny ped faces and ABC horizon sequence. Colour A- horizon is dark brown (7.5YR3/2) and B-horizon is dark red (5YR4/4) to dark reddish brown (5YR3/3). Texture Clay throughout. Structure A- horizon is weak, medium, subangular blocky and B- horizon is moderate, medium, subangular and angular blocky. Consistence A- horizon is friable when moist, sticky and plastic when wet and B- horizon friable to firm when moist, sticky and plastic when wet. Chemical properties The pH-H20 is 5.6 in the topsoil and ranges 5.9 to 5.6 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.05 in the A- horizon and between 0.88 and 0.3 in the B-horizon. CEC- soil is 23.2 me/100g in the topsoil and 21.9- 19.1 me/100g in the subsoil. The base saturation is 27% in the A- horizon and between 25 and 17% in the B-horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco mollic NITISOLS. USDA typic PALEUDOLL.

Representative soil profile Appendix 3 profile No. 23

62 Unit U1PC Total area 170ha Parent Material Consolidated pyroclastic rocks. Macro relief Undulating to rolling (slope classes B, C and D). Surface stoniness/rockiness In places stony and rocky

Vegetation/landuse Wooded bushland to woodlands (Grevillea robusta, Cordia abyssinica, Croton macrostachyus); cultivation of bananas, sunflower, cotton, pigeon peas, etc and semi-extensive grazing. Soils, general Complex of somewhat excessively drained to well drained, dark reddish brown to brown .gravelly sandy clay soils of varying depth, consistence, rockiness and stoniness with AC or ABC horizon sequence. Colour A- horizon is dark brown (7.7YR3/2) to very dark grey (10YR2/3) and B- horizon is dark reddish brown (5YR3/4) to brown(7.5YR3/4). Texture Sandy clay to clay throughout. Structure Moderate, medium ,subangular and angular blocky throughout. consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout. Chemical properties The pH-H20 is 6.1 in the topsoil and ranges 5.8 to 5.6 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.3 in the A- horizon and between 1.0 and 0.5 in the B horizon. CEC- soil is 31.5 me/100g in the topsoil and 29.7-18.6 me/100g in the subsoil. The base saturationis 50% in the A- horizon and between 33 and 49 for the B-horizon.The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco LEPTOSOLS, ferric ACRISOLS anddystric CAMBISOLS, partly lithic and stony phases USDA

Representative soil profile Appendix 3 profile No.24

63 Unit UIVr Total area 16360ha Parent material Various volcanic rocks. Macro relief Gently undulating to undulating (slope classes A, B and C). Vegetation/ landuse Wooded bushland to woodlands (Grevillea robusta, Juniperusprocera, Erythrina abyssinica, Combretum molle, Acacia mearnii, Cordia abyssinica, Acacia polyacantha); cultivation of coffee, bananas, sunflower, cotton, pigeon peas beans tobacco, etc and semi-extensive grazing or zero grazing.

Soils, general Well drained, very deep,dark red to dark reddish brown, friable to firm clay with 20 - 30 cm humic topsoil shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/2 and B- horizon dark red (2.5YR3/6) dark reddish brown (5YR3/4). Texture Clay throughout. Structure A- horizon moderate, medium, subangular blocky and B- horizon is strong, medium to coarse, angular and strong, medium, prismatic. consistence : Friable to firm when moist, sticky and plastic when wet throughout. Chemical properties : The pH-H20 is 5.6 throughout while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.02 in the A- horizon and between 1.01 and 0.27 in the B horizon. CEC-soil is 25.2 me/100g in the topsoil and 24.6- 15 me/100g in the subsoil. The base saturationis 23% in the A- horizon and between 29 and 16 for the B-horizon.The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco mollic and dystric NITISOLS

USD A typic PALEUDOLLS and orthoxic PALEHUMULTS.

Representative soil profile : Appendix 3 profile No. 25

64 Unit UlVr Total area 16360ha Parent material Various volcanic rocks. Macro relief Gently undulating to undulating (slope classes A, B and C). Vegetation/landuse Wooded bushland to woodlands {Grevillea robusta, Juniperusprocera, Erythrina abyssinica, Combretum molle, Acacia mearnii, Cordia abyssinica, Acacia polyacantha); cultivation of coffee, bananas, sunflower, cotton, pigeon peas beans tobacco, etc and semi-extensive grazing or zero grazing.

Soils, general Well drained, very deep,dark red to dark reddish brown, friable to firm clay with 20 - 30 cm humic topsoil shiny ped faces and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/2 and B- horizon dark red (2.5YR3/6) dark reddish brown (5YR3/4). Texture Clay throughout. Structure A- horizon moderate, medium, subangular blocky and B- horizon is strong, medium to coarse, angular and strong, medium, prismatic. consistence Friable to firm when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.6 throughout while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.02 in the A- horizon and between 1.01 and 0.27 in the B horizon. CEC-soil is 25.2 me/100g in the topsoil and 24.6- 15 me/100g in the subsoil. The base saturationis 23% in the A- horizon and between 29 and 16 for the B-horizon.The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco mollic and dystric NITISOLS

USDA typic PALEUDOLLS and orthoxic PALEHUMULTS.

Representative soil profile Appendix 3 profile No. 25

64 Unit UlVrp Total area 5910ha Parent material Various volcanic rocks. Macro relief Undulating to rolling (slope classes B, C and D). Surface stoniness/rockiness In places fairly stony and rocky. Vegetation/landuse wooded bushland (Grevillea robusta, Cordia abyssinica, Croton macrostarchyus); cultivation of sorghum, bananas, sunflower, cotton, pigeon peas, etc and semi-extensive grazing. Soils, general Well drained, shallow to moderately deep, dark red to dark reddish brown, friable, sandy clay loam to clay with ABC horizon sequence. Colour A- horizon is dark reddish brown(5YR3/3) to dark brown (7.5YR3/2) while B- horizon dark red (2.5YR3/6) to dark reddish brown (5YR3/4). Texture Sandy clay loam to clay throughout.

Structure A- horizon is moderate, medium, granular and subangular blocky and B- horizon is weak to moderate, medium subangular blocky. Consistence Friable when moist,slightly sticky to sticky and slightly plastic to plastic when wet throughout. Chemical properties The pH-H20 is 6.4 throughout while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.07 in the A- horizon and between 0.68 and 0.57 in the B horizon. CEC-soil is 23.2 me/100g in the topsoil and 17.4- 14.6 me/100g in the subsoil. The base saturationis 33% in the A- horizon and 31 for the B-horizon. The dominant clay mineral are kaolinite and illite.

Soil classification FAO - Unesco luvic and haplic PHAEOZEMS, and dystric CAMBISOLS; partly lithic phase USDA udic ARGIUSTOLLS, typic HAPLUSTOLLS, and typic DYSTROPEPTS

Representative soil profile Appendix 3 profile No. 26

65 Unit UlXrp Total area 1250ha Parent material Various rocks. Macro relief Undulating to rolling (slope classes B, C and D). Surface stoniness/rockiness In places fairly stony and rocky. Vegetation/landuse Wooded bushland (Grevillea robusta, Cordia abyssinica, Croton macrostachyus);cu\tivation of sorghum, bananas, sunflower, cotton, pigeon peas, etc and semi-extensive grazing. Soils, general Well drained, moderately deep, yellowish red to dark reddish brown, friable, sandy clay loam to clay in places rocky and stony, with ABC horizon sequence. Colour A- horizon is dark reddish brown(5YR4/4) to dark yellowish brown (7.5YR4/4 and B- horizon is yellowish red (5YR4/8) to dark reddish brown (5YR3/4). Texture Sandy clay loam to clay throughout. Structure A- horizon moderate, fine, subangular blocky while B- horizon is moderate, medium, subangular blocky and weak, medium angular blocky. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout. Chemical properties The pH-H20 is 5.9 in the A-horizon and 5.7 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.14 in the A- horizon and between 0.64 and 0.59 in the B horizon. CEC-soil is 22 me/100g in the topsoil and 20 me/100g in the subsoil. The base saturationis 83% in the A- horizon 75 and 73 for the B- horizon. The dominant clay mineral are kaolinite and illite.

FAO Unesco ferric ACRISOLS, partly stony phase and chromic LUVISOLS partly pisoferric an stony phase USDA typic PLINTHUSTULTS and typic PLINTHUSTALFS

Representative soil profile Appendix 3 profile No. 27

66 Unit U2Qp Total area 1700ha Parent material Granitoid gneisses and migmatites. Macro relief undulating (slope classes B, C and D) Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, moderately deep, dark reddish brown, friable, gravelly, clay loam to sandy clay and ABC horizon sequence. Colour A- horizon is dark brown(7.7YR3/4) to dark reddish brown (5YR3/4) and B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Sandy clay loam to sandy clay throughout. Structure Moderate, medium, subangular blocky throughout. consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic throughout.

Representative soil profile none

Remarks Severe gully and rill erosion were observed. Surface sealing is very strong especially where the vegetation cover has been removed.

67 Unit U2QP Total area 1700ha Parent material Granitoid gneisses and migmatites. Macro relief undulating (slope classes B, C and D) Surface stoniness/rockiness Stony and rocky Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, shallow, dark reddish brown, friable, gravelly, clay loam to clay in places rock and stony, with strong surface sealing and ABC or AC horizon sequence. Colour A- horizon is dark brown (7.7YR3/4) to dark reddish brown (5YR4/4) and B- horizonis red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR4/4). Texture Gravely clay loam to clay throughout. Structure Weak to moderate, fine to medium subangular blocky throughout. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic throughout.

Representative soil profile none

68 Unit U2QC Total area 5975ha Parent material Granitoid gneisses and migmatites Macro relief Undulating to rolling (slope classes B, C and D). Surface stoniness/rockiness : Vvariably stony and rocky. Vegetation/landuse Same as U2QP.

Soils, general Complex of well drained, moderately deep to deep, red to dark reddish brown, fairly rocky and stony, gravelly, clay loam to clay with ABC horizon sequence and strong surface sealing. well drained, shallow to moderately deep, red to dark reddish brown, rocky to very rocky, stony to very stony, gravelly, sandy clay loam to clay with ABC or AC horizon sequence and strong surface sealing. Colour Red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4) throughout in all the components of the complex. Texture -Gravely clay loam to clay throughout. -Gravelly sandy clay loam to clay throughout. Structure Moderate, medium, subangular, blocky throughout. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic throughout.

Representative soil profile none

69 Unit U2Fr Total area 7938ha Parent material Hornblende and biotite gneises. Macro relief undulating (slope classes B, C and D) Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, deep to very deep, dark red to dark reddish brown, friable, sandy clay to clay in places gravelly,with ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) while B- horizon is dark red (2.5YR3/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Sandy clay to clay throughout. Structure Moderate, medium, subangular blocky throughout. Consistence Friable when moist, sticky and plastic when wet throughout.

Representative soil profile none

70 Unit U2hrP Total area 17673ha Parent material Hornblende and biotite gneises. Macro relief Undulating (slope classes B, C and D) Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, shallow, red to dark reddish brown, friable, sandy loam to sandy clay loam in places fairly rocky and stony, with ABC or AC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) while B horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Sandy clay loam to sandy clay throughout. Structure Weak to moderate, fine to medium, subangular blocky throughout. Consistence Friable when moist, slightly sticky and slightly plastic throughout. Representative soil profile none

71 Unit U2FC Total area 12787ha Parent material Hornblende and biotite gneises. Macro relief undulating (slope classes B, C and D) Surface stoniness/rockiness In places stony and rocky Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Complex of - well drained, moderately deep to deep, dark red to dark reddish brown, friable, clay loam to clayin places fairly rocky and stony, with ABC horizon sequence. -well drained, moderately deep to deep, dark red to dark reddish brown, friable to firm, clay loam to clay in places over pisoferric or pisocalcic material, with ABC or AC horizon sequence. -well drained, shallow to moderately deep, dark red to strong brown, gravelly clay loam to clay in places rocky to very rocky and stony to very stony With AC or ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) while B- horizon is dark red (2.5YR3/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Clay loam to clay throughout. Structure Weak to moderate, fine to medium, subangular blocky throughout. Consistence Friable when moist,slightly sticky to sticky and slightly plastic to plastic when wet throughout.

Representative soil profile none

72 Unit UzUrP Total area 5800ha Parent material Various Basement System rocks (metamorphic rocks). Macro relief Undulating (slope classes B,and C) Surface stoniness/rockiness Slightly to fairly stony and rocky. Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, moderately deep to deep, red to dark brown, friable, slightly to fairly rocky and stony sandy clay to clay with strong surface sealing and ABC horizon sequence Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (10YR3/3) while B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR4/4). Texture Sandy clay to clay throughout. Structure Moderate, medium subangular blocky throughout. Consistence Friable when moist, sticky and plastic when wet throughout.

Representative soil profile none

73 Unit uzuc Total area 20629ha Parent material Various Basement System rocks (metamorphic rocks). Macro relief Undulating (slope classes B,and C) Surface stoniness/rockiness Slightly to fairly stony and rocky. Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Complex of -well drained, deep, red to dark reddish brown, friable, slightly rocky, slightly stony, clay loam to clay, with string surface sealing and ABC horizon sequence. -well drained, moderately deep to deep,red to dark reddish brown, friable to firm, fairly rocky, stony, gravelly, clay loam to clay in places over pisocalcic material, with strong surfaces sealing and ABC horizon sequence. -well drained, shallow, dark reddish brown, friable, very rocky,very stony, gravelly sandy loam to sandy clay loam with strong surface sealing and ABC or AC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) to dark brown (10YR3/3) while B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR4/4) in all the components of the complex. Texture -Clay loam to clay throughout. -Gravelly clay loam to clay throughout. -Gravelly sandy clay to sandy clay throughout. Structure Moderate, medium to coarse, subangular blocky throughout the components of the complex. Consistence -Friable when moist, sticky and plastic throughout. -Friable to firm when moist, sticky and plastic when wet. -Friable when moist, non sticky to slightly sticky and non plastic to slightly plastic when wet throughout. Chemical properties -The pH-H20 ranges from 5.9-6.1 and EC is less than 0.1 mmhos/cm in the topsoil and the subsoil. Organic carbon percentage 0.13 in both the topsoil and subsoil. CEC-soil ranges from 7 .3 - 14.6 me/100g throughout. The Base saturation is more than 53 % throughout. - The dominant clay mineral are kaolinite and illite throughout the complex. Soil classification FAO - Unesco -chromic LUVISOLS -chromic and chromo*-calcic LUVISOLS, stony and partly pisocalcic phases -LEPTOSOLS, and eutric and dystric REGOSOLS, lithic and stony phases USDA -udic RHODUSTALFS

74 -udic RHODUSTALFS -lithic EUSTROPEPTS AND DYSTROPEPTS. Representative soil profile : Appendix 3 profile No. 28

75 Unit U2Brl Total area 1080ha Parent material Basalt of Mt kenya and Nyambene series Macro relief Undulating (slope classes A and B Vegetation/landuse Wooded bushland (Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis); cultivation of maize, beans, tobacco, sunflower, cotton, pegionpeas and semi-extensive grazing. Soils, general Well drained, very deep,red to dark reddish brown, friable clay with shiny ped faces, humic topsoil and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/3 - 3/2) and B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Clay throughout. Structure A- horizon is moderate, medium to coarse subangular blocky while B- horizon is strong, medium to coarse subangular and angular blocky. consistence Friable when moist, sticky and plastic when wt throughout. Chemical properties The pH-H20 is 5.9 in the A-horizon and 5.7 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.14 in the A- horizon and between 0.64 and 0.59 in the B horizon. CEC-soil is 22 me/100g in the topsoil and 20 me/100g in the subsoil. The base saturationis 83% in the A- horizon 75 and 73 for the B- horizon. The dominant clay mineral is kaolinite Soil classification FAO - Unesco mollic NITISOLS USDA udic PALEUSTOLL

Representative soil profile Appendix 3 profile No. 29

Remarks The whole of this unit is under irrigation in the Mitunguu irrigation scheme.

76 Unit U2Br2 Total area 2240ha Parent material Basalt of Mt. Nyambene series Macro relief Gently undulating to undulating (slope classes A and B). Vegetation/landuse Wooded bushland to wooded grassland (Combretum molle, Acacia tortilis, Phyllanthus somalensis); shifting cultivation of maize, beans, sunflower, cotton, pigeon peas and extensive grazing. Soils, general Well drained, very deep, dusky red to dark reddish brown, friable clay loam to clay with ABC horizon sequence. Colour A- horizon is dark reddish brown (2.5YR3/4 -5YR3/4) and B- horizon is dusky red (10R3/3) to dark reddish brown (2.5YR3/4 - 5YR4/4). Texture Clay loam to clay throughout. Structure A- horizon is weak, medium to coarse subangular blocky while- B horizon weak, medium, subangular blocky and weak, fine, angular blocky grading to massive. Consistence Friable when moist, sticky and plastic when wt throughout.

Representative soil profile none

77 Unit U2BP Total area 200ha Parent material Basalt of Mt. Nyambene series Macro relief Undulating (slope classes B). Vegetation/landuse Wooded bushland to wooded grassland (Çombretum molle, Acacia tortilis, Phy liant hus somalensis); shifting cultivation of maize, beans, sunflower, cotton, pigeon peas and extensive grazing. Soils, general Well drained, shallow to moderately deep, reddish brown to dark brown, friable, gravelly clay loam to clay; with ABC horizon sequence. Colour A- horizon is dark greyish brown (10YR3/2) and B horizon dark reddish brown (5YR4/4) to dark brown (10YR4/3). Texture Gravelly clay loam to clay throughout. Structure Weak, fine to medium, subangular, blocky throughout Consistence Friable when moist, sticky and plastic when wt throughout.

Representative soil profile none

78 Unit U2Xrp Total area 2400ha Parent material Various rocks. Macro relief Undulating (slope classes B,and C) Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, moderately deep to deep, red to dark red, friable, sandy clay loam to clay with ABC horizon sequence Colour A- horizon is dark reddish brown (5YR3/4) -2.5YR3/4) while B- horizon is red (2.5YR4/6) to dark red (2.5YR3/6). Texture Sandy clay loam to clay throughout.

Structure A- horizon is weak, fine, subangular, blocky and crumbs while B- horizon is strong, medium, subangular and angular blocky. Consistence Friable when moist, sticky and plastic throughout.

Representative soil profile none

79 Unit U2XA Total area 3720ha Parent material Various rocks. Macro relief Undulating (slope classes Band C) Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii, Acacia drepanolobium); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Association of -soils of unit U2Xrp -well drained, moderately deep to deep, dark reddish brown to dark greyish brown, calcareous, friable to firm, slightly gravelly, sandy clay to clay in places cracking and with slickensides and ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/4) to very dark grayish brown (10YR3/2) while B- horizon is dark greyish brown (10YR3/3) to black (10YR2/1). Texture Slightly gravely sandy clay to clay throughout

Structure Strong, medium to coarse angular blocky throughout. Consistence Firm when moist, sticky and plastic throughout. Chemical properties The pH-H20 is 5.1 throughout and EC is less than 0.3 mmhos/cm in the topsoil and the subsoil. Organic carbon percentage ranges from 0.29-0.26 decreasing with depth. CEC-soil ranges from 16.1 - 11 me/100g throughout. The Base saturation ranges form 32 to more than 80% throughout. The dominant clay minerals is montmollironite.

Soil classification FAO - Unesco -Same as unit UXrp -vertic and calcic LUVISOLS USDA - Same as unit UXrp. -typic and vertic HAPLUSTALFS

Representative soil profile Appendix 3 profile No. 30

80 Unit U2XC Total area 5730ha Parent material Various rocks. Macro relief Undulating (slope classes B and C) Surface stoniness/rockiness Stony, very rocky and bouldery. Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Terminalia brownii); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Complex of -well drained, moderately deep to deep, red to dark reddish brown, friable, slightly rocky, stony, clay loam to clay with ABC horizon sequence. -well drained, shallow, dark reddish brown, bouldery, very stony, gravelly, sandy loam to clay loam; in places over petroplinthite (murram) with ABC or AC horizon sequence.

Colour A- horizon is dark reddish brown (5YR3/4) and B-horizon is red (2.5YR4/6) to dark (7.5YR3/2

Texture Clay loam to clay throughout. Gravely sandy clay loam to clay throughout. Structure Weak to moderate, medium to coarse subangular blocky throughout the components of the complex. Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout. Chemical properties The pH-H20 is 5.6 in the A-horizon and 6.5 in the B- horizon while the EC is less than 0.1 mmhos/cm. Organic carbon percentage is 0.58 in the A- horizon and between 0.58 and 0.26 in the B horizon. CEC-soil is me/100g in the topsoil and me/100g in the subsoil. The base saturationis % in the A- horizon and for the B- horizon. The dominant clay mineral are kaolinite and illite. Soil classification FAO - Unesco chromic LUVISOLS and orthic ACRISOLS, stony phase eutric REGOSOLS and dystric and eutric CAMBISOLS; partly lithic, petroferric and stony phases USDA udic RHODUSTALFS and typic RHODUSTULTS lithic and typic EUSTROPEPTS, lithic and typic DYSTROPEPTS. Representative soil profile Appendix 3 rofile No. 31

81 3.3.8 Soils of the plains

Unit PnBrl Total area 6817ha Parent material Basalt of Nyambene series Macro relief Undulating (slope classes A and B) Vegetation/landuse Grassland to Wooded bushland {Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis, Combretum collinum Vitex doniana); cultivation of maize, beans, tobacco, sunflower, cotton, pigeonpeas and semi- extensive grazing. Soils, general Well drained, very deep,red to dark reddish brown, friable clay with shiny ped faces and ABC horizon sequence. Colour A-horizon is dark reddish brown (5YR3/34- 3/3) and B- horizon is red (2.5YR4/6) to dark reddish brown (2.5YR3/4 - 5YR3/4). Texture Clay throughout. Structure A- horizon is moderate to strong, medium, subangular and angular blocky. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is 5.9 in the topsoil and 7.8 - 7.2 in the B horizon while EC is less than 0.1 mmhos/cm. Organic carbon percentage is 1.46 in the topsoil and 0.89 - 0.48 in the subsoil. CEC-soil is 19 me/100g in the topsoil and 16 - 9 in the subsoil. The Base saturation ranges from 48- 31% in the topsoil and the subsoil. The dominant clay mineral is kaolinite . Soil classification FAO - Unesco humic and dystric NITISOLS USDA typic PALEUSTULTS

Representative soil profile Appendix profile No.32

Remarks The whole of this unit is under irrigation in the Mitunguu irrigation scheme.

82 Unit PnBr2 Total area 1030ha Parent material Basalt of Mt Nyambene series Macro relief Gently undulating to undulating (slope classes A and B). Vegetation/ landuse Wooded bushland to wooded grassland (Combretum molle, Acacia tortilis, Phyllanthus somalensis); shifting cultivation of maize, beans, sunflower, cotton, pigeon peas and extensive grazing. Soils, general Well drained, very deep, dusky red to dark reddish brown, friable, clay loam to clay with ABC horizon sequence. Colour A- horizon is dark reddish brown (2.5 YR3/4 -5YR3/4) and B- horizon is dusky red (10R3/3) to dark reddish brown (2.5YR3/4 - 5YR4/4). Texture Clay loam to clay throughout. Structure A- horizon is weak, medium to coarse, subangular blocky whilst B- horizon is weak, medium, subangular blocky and weak, fine angular blocky grading to massive. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 ranges from 5.4-5.5 and the EC is less than 0.1 mmhos/cm. Organic carbon percentage ranges from 0.59 - 0.34 in the topsoil and the B- horizon. CEC-soil ranges from 18-13 me/100g. The Base saturation ranges from 60-7% throughout. The dominant clay mineraL is kaolinite Soil classification FAO - Unesco chromic ACRISOLS USDA udic RHODUSTALTS

Representative soil profile Appendix 3 profile No.33

83 Unit PnBrP Total area 640ha Parent material Basalt of Nyambene series Macro relief Undulating (slope classes A and B) Vegetation/landuse Grassland to Wooded bushland (Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis Combretum collinum Vitex doniana) ; continous and shifting cultivation of maize, beans, tobacco, sunflower, cotton, pegionpeas and semi-extensive grazing. Soils, general Well drained, moderately deep to deep, dark red to dark reddish brown, friable gravely clay over pisoferric material (murram); with ABC horizon sequence. Colour A- horizon is dark reddish brown (5YR3/34- 3/3) and B- horizon is dark red (2.5YR3/6) to dark reddish brown ( 5YR3/4). Texture Clay loam to clay throughout. Structure Moderate, medium, subangular blocky. Consistence Friable when moist, sticky and plastic when wet throughout.

Representative soil profile none

84 Unit PnBbPl Total area 1700ha Parent material Basalt of Mt Nyambene series. Macro relief Flat to gently undulating (slope classes A and B) Vegetation/landuse Grassland to Wooded bushland {Combretum molle, Acacia polyacantha,Lantana camara, Phyllanthus somalensis, Combretum collinum, Vitex doniana) \contmo\is and shifting cultivation of maize, beans, tobacco, sunflower, cotton, pigeonpeas and semi-extensive grazing. Soils, general Well drained, shallow to moderately deep, brown to dark greyish brown, friable, gravelly, clay loam to clay over pisoferric material (murram), with abc horizon sequence. in places over rock. Colour A- horizon is very dark greyish brown (10YR3/1) to black (10YR2.5/1) and B- horizon is brown (10YR3/3) to dark greyish brown (10YR3/4). Texture Clay loam to clay throughout. Structure Moderate, medium to coarse, subangular blocky grading to massive. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout.

Representative soil profile none

Inclusions Imperfectly drained, moderately deep, very dark greyish brown to black firm, clay.

85 Unit PnBbP2 Total area 3270ha Parent material Basalt of Mt Nyambene series. Macro relief Flat to gently undulating (slope classes A and B) Vegetation/landuse Grassland to Wooded bushland (Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis, Combretum collinum); continous and shifting cultivation of maize, beans, tobacco, sunflower, cotton, pegionpeas and extensive grazing. Soils, general Well drained, shallow, dark reddish brown to very dark brown, gravelly, clay loam to clay over pisoferric material (murram) with ABC horizon sequence. Colour A- horizon is very dark greyish brown (10YR3/1) to black (10YR2.5/1) while B- horizon is dark reddish brown (5YR3/4) to dark brown (10YR3/4). Texture clay loam to clay throughout. Structure Moderate, medium to coarse, subangular blocky grading to massive. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout.

86 Unit PnPC Total area 220ha Parent material consolidated pyroclastic rocks (lahar complex). Macro relief Flat to gently undulating (slope classes A and B) Vegetation/landuse Wooded bushland (Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis, Combretum collinum) ;continous and shifting cultivation of maize, beans, tobacco, sunflower, cotton, pigeonpeas and extensive grazing. Soils, general complex of well drained, dark reddish brown to dark brown, rocky, friable, sandy clay soils of varying depth and stoniness Colour Dark reddish brown (5YR3/4) to dark brown (7.5YR3/2) throughout. Texture Sand clay loam throughout. Structure Moderate, medium to coarse, subangular blocky. Consistence Friable when moist, slightly sticky and slightly plastic when wet throughout. Representative soil profile none

88 Unit PnXr Total area 2250ha Parent material Various rocks. Macro relief gently undulating (slope classes A and B). Vegetation/landuse Bushland thicket to wooded bushland (Acacia tortilis, Commiphora africana, Acacia mellifera, Acacia nilotica, Termirialia brownii, Acacia drepanolobium); shifting cultivation of maize, millet, sorghum, cotton, green grams, cow peas and extensive grazing. Soils, general Well drained, deep, dark red, friable clay; with ABC horizon sequence. Colour A -horizon is reddish brown (2.5YR4/4) to yellowish red (5YR4/6) and B- horizon is dark red (2.5YR3/6). Texture Moderate, medium, angular blocky and strong medium subangular blocky. Structure Clay throughout. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 ranges from 6 to 5 in the topsoil and 5.2-4.8 in the B- horizon while EC is less than 0.2 mmhos/cm. Organic carbon percentage varies from 2.35 - 0.81 in the topsoil and 0.65 - 0.31 in the subsoil. CEC-soil ranges from 22.4 - 15.1 me/100g throughout. The Base saturation is 39 - 35% in the topsoil and ranges from 31-23% in the B-horizon. The dominant clay mineral is kaolinite . Soil classification FAO - Unesco chromic ACRISOLS and chromic LUVISOLS. USDA typic RHODUSTULTS and oxic RHODUSTALFS.

Representative soil profile Appendix 3 profile No.34

89 Unit PnXr - PnBbP2 Total area 1740ha Parent material some as unit PnXr an unit PnBbP2 Macro relief Flat to gently undulating (slope classes A and B) Vegetation/landuse Same as in unit PnBbP2.

Soils, general The soils are same as soils of unit PnXr and unit PnBbP2. Soils of unit PnXr occur in the gently undulating parts of the unit while those of unit PnBbP2 occur in the flat parts of the unit. Colour A- horizon is very dark greyish brown (10YR3/1) to black (10YR2.5/1) while B- horizon is dark reddish brown (5YR3/4) to dark brown (10YR3/4). Texture clay loam to clay throughout. Structure Moderate, medium to coarse, subangular blocky grading to massive. Consistence Friable when moist, slightly sticky to sticky and slightly plastic to plastic when wet throughout.

Chemical properties The pH-H20 IS5.9 while EC is less than 0.2 mmhos/cm. Organic carbon percentage varies from 1.11 to 0.93 throughout. CEC-soil ranges from 20-19 me/100g throughout. The Base saturation is 64 -52% throughout. The dominant clay mineral is kaolinite . Soil classification FAO - Unesco chromic CAMBISOLS USDA typic DYSTROPEPTS.

Representative soil profile : Appendix 3 profile No.35

90 Unit PdBr Total area 2460ha Parent material Basalt of Mt.Kenya and Nyambene series Macro relief Undulating (slope classes A and B Vegetation/ landuse Wooded bushland to wooded grasslands (Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis, Combretum collinum Vitex doniana); cultivation of maize, beans, tobacco, sunflower, cotton, pigeon peas sorghum, cow peas and semi-extensive grazing. Soils, general Well drained, very deep, dark reddish brown, friable to firm clay with shiny ped faces, 30 - 30 cm humic topsoil and ABC horizon sequence. Colour A- horizon is dark yellowish brown ( 10YR3/4) to dark brow (7.5YR3/2) and B- horizon is dark reddish brown (2.5YR2.5/4 - 5YR3/4). Texture Clay throughout. Structure Strong, medium granular and subangular blocky in the topsoil grading to strong, fine to medium angular blocky in the subsoil. Consistence Friable when moist, sticky and plastic when wet throughout. Representative soil profile none

91 3.3.9 Soils of the major and minor valleys

Unit V1PC Total area 1934ha Parent material Consolidated pyroclastic rocks (lahar complex. Macro relief Hill to rollling at the valley sides and undulating to flat at the valley bottom. Vegetation/landuse Wooded bushland to woodlands (Grevillea robusta, Juniperus procera, Erythrina abyssinica, Combretum molle,Acacia meansii, Cordia abyssinica, Acacia polyacantha); cultivation of coffee, bananas, sunflower, cotton, pigeonpeas, beans, tobacco, etc and semi-extensive grazing or zero grazing of dairy cattle. Soils, general Complex of -well drained, moderately deep to deep, dark reddish brown, friable clay with ABC horizon sequence; in places shiny ped faces, -well drained, shallow to moderately deep, dark reddish brown, friable, slightly rocky to rocky, slightly stony to stony clay in places over petroferric material (murrain); with ABC horizon sequence. Colour Dark reddish brown (5YR3/4) to dark brown (7.5YR3/2) throughout. Texture Clay to clay loam throughout. Structure Strong to moderate, medium, subangular blocky throughout. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 ranges from 4.4-4.3 throughout while EC is less than 0.1 mmhos/cm. Organic carbon percentage is 2.6 in the topsoil and not determined in the subsoil. CEC-soil ranges from 16.3 - 12.5 me/100g throughout. The Base saturation ranges from 13.5 to 11.2% throughout. The dominant clay mineral is kaolinite, illite and some vermiculite. Soil classification FAO - Unesco dystric NITISOLS* and humic and chromic* ACRISOLS. chromic* ACRISOLS and chromic LUVISOLS, partly petroferric, stony and lithic phases. USDA typic PALEUDULTS and typic RHODUDULTS. typic RHODUDULTS and typic and lighic RHODUSTALFS. Representative soil profile Appendix 3 profile No.36

92 Unit VIXrp Total area 1590ha Parent material Various rocks Macro relief Undulating (slope classes A and B Vegetation/landuse Wooded bushland to bushland thicket {Combretum molle, Acacia polyacantha, Lantana camara, Phyllanthus somalensis, Combretum collinum, Vitex doniana); cultivation of maize, beans, tobacco, sunflower, cotton, pigeon peas sorghum, cow peas and semi-extensive grazing. Soils, general Well drained, moderately deep to deep, red to dark reddish brown, friable clay with ABC horizon sequence and in places shiny ped faces. Colour A- horizon is dark brown ( 7.5YR3/2) and B- horizon is red (2.5YR4/6) dark reddish brown (2.5YR2.5/4 - 5YR3/4). Texture Clay throughout. Structure Moderate, medium, subangular blocky angular blocky. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is about 6.1 in the topsoil and ranges from 6 - 5.6 in the B- horizon while EC is less than 0.1 mmhos/cm. Organic carbon percentage varies from 1.02 to 0.59 decreasing with depth. CEC-soil ranges from me/100g throughout. The Base saturation ranges from 50 to 40% in the topsoil and 29-33% in the B- horizon. The dominant clay mineral is kaolinite. Soil classification FAO - Unesco humic NITISOLS and chromic ACRISOLS, partly lighic phase. USDA udic PALEUSTULTS and typic and lithic RHODUSTULTS.

Representative soil profile Appendix 3 profile No. 37

93 Unit V2Pr Total area 2720ha Parent material Consolidated pyroclastic rocks (lahar complex. Macro relief Undulating; slopes 2-6% Vegetation/landuse Wooded bushland to bushland thicket (Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis, Combretum collinum Vitex doniana) ; cultivation of maize, beans, tobacco, sunflower, cotton, pigeon peas sorghum, cow peas and semi-extensive grazing. Soils, general Well drained, deep to very deep, dark red to dark reddish brown, friable clay in places rocky with ABC horizon sequence. Colour A- horizon is dark brown ( 7.5YR3/2) to dark reddish brown (2.5YR2.5/2 and B- horizon is dark red (2.5YR3/6) dark reddish brown ( 5YR32.5/3). Texture Clay throughout. Structure Moderate, fine to medium subangular blocky angular blocky throughout. Consistence Friable when moist, sticky and plastic when wet throughout.

Representative soil profile none

94 Unit V2PC Total area 2290ha Parent material Consolidated pyroclastic rocks (lahar complex. Macro relief Undulating; slopes 2-6%

Surface stoniness/rockiness : Fairly/slightly Vegetation/landuse Wooded bushland to bushland thicket (Combretum molle, Acacia polyacantha,Lantana camara, Phyllanthus somalensis Combretum collinum, Vitex doniana);exter\sive grazing.

Soils, general Complex of well drained,dark reddish brown, clay soils of varying depth, consistence, rockiness and stoniness; with ABC or AC horizon sequence.

Representative soil profile none

95 Unit V2XC Total area 5776ha Parent material Various rocks. Macro relief Flat; slopes 0-2% Surface stoniness/rockiness Fairly/slightly Vegetation/landuse Wooded bushland to bushland thicket (Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis Combretum collinum, Vitex doniana); extensive grazing. Soils, general Complex of well drained to imperfectly drained, friable soils of varying depth, colour, rockiness, stoniness and texture; in places mottled, with ABC or AC horizon sequence.

Representative soil profile none

96 3.3.10 Soils of the Bottomlands

Unit BPC Total area 520ha Parent material Consolidated pyroclastic rocks (lahar complex) Macro relief Flat; slopes 0-2% Surface stoniness/rockiness None Vegetation/landuse Wooded bushland to bushland thicket (Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis, Combretum collinum, Vitex doniana) ;extensive grazing.

Soils general Complex of -imperfectly drained, shallow to moderately deep, dark brown to dark greyish brown, friable, gravelly clay loam in places over pisoferric material (murram) and mottled With ABC horizon sequence. -imperfectly drained to poorly drained, moderately deep to deep, very dark greyish brown to black, mottled, friable to firm, clay loam to clay; in places cracking , with ABC or AC horizon sequence.

Representative soil profile : none

97 Unit BXd Total area 1901ha Parent material Various rocks. Macro relief Flat; slopes 0-2% Surface stoniness/rockiness None Vegetation/landuse Wooded bushland to bushland thicket (Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis, Combretum collinum, Vitexdoniana); extensive grazing. Soils, general Imperfectly drained to poorly drained, moderately deep to deep, very dark greyish brown to black, firm, calcareous, cracking clay; in places stratified, with ABC or AC horizon sequence. Colour A- horizon is very dark greyish brown ( 10YR3/1) and B- horizon is very dark greyish brown ( 10YR3/1) Texture Clay throughout. Structure Moderate, fine, subangular blocky and angular blocky to fine prismatic. Consistence Friable when moist, sticky and plastic when wet throughout. Chemical properties The pH-H20 is about 6.8 in the topsoil and ranges from 7.2 - 7 in the B- horizon while EC ranges from 0.19 to 0.13 mmhos/cm. Organic carbon percentage varies from 0.82 to 0.73 decreasing with depth. CEC-soil ranges from 47 to 45 me/100g throughout. The Base saturation ranges from 80 to 100% Soil classification FAO - Unesco pellic VERTISOLS and eutric FLUVISOLS, pisocalcic phase USDA typic USTERTS

Representative soil profile Appendix 3 profile No. 38

98 Unit BXg Total area 693ha Parent material Various rocks Macro relief Flat; slopes 0-2% Surface stoniness/rockiness None Vegetation/landuse Wooded bushland to bushland thicket {Combretum molle, Acacia polyacantha.Lantana camara, Phyllanthus somalensis, Combretum collinum, Vitex doniana);extensive grazing. Soils, general poorly drained, very deep, very dark greyish brown, mottled, friable, clay loam to sandy clay; with topsoil of un-decomposed material of varying depth, with ABC or AC horizon sequence.

Representative soil profile none

99 Soil classification correlation and genesis aspects

I. Introduction classification units unlike soil mapping units described earlier are abstractions although the distinction ilways easily understood. Mapping units are units of land which can be separated geographically ally in the field, can be drawn and shown on maps (soil maps) and can be used as units for land evaluati oses. For the accommodation of the soils encountered in the survey area into an internationally recogniz ework of classification, the FAO-UNESCO legend (1974) was applied. Considerations on the choice ;ystem are given in the Kindaruma report (van de Weg and Mbuvi, 1975). The important chemical ai ical differences in characteristics of the soils of the survey area- in the system can be used for national ai îational correlation purposes. In the Chuka area the following major classification units are recogniz- ;ols, Andosols. Acrisols, Luvisols, Ferralsols, Vertisols, Phaeozems, Gleysols. and Lithosols. v is a short description of these soils which should be read together with appendix 4, For a comprehensr iption of all soils in the FAO-UNESCO legend, and the definition of the diagnostic horizons involve' :nce is made to volume I of the "Soil Map of the World" (FAO-UNESCO, 1974). The FAO legend h; chosen here as a system of reference for soil correlation purposes. The units are based on measurable ai vable characteristics that are felt to reflect the known genetic processes. It also gives particular attentie pical soils, as they occur in the field, being based on many field correlation trips and regional so ation meetings with national experts.

Major soil classification units

)il classification system which have been applied during this soil survey are the FAO-Unesco (1974) wit modification by the Kenyan concepts, the USDA -Soil Taxonomy (1964), and the FAO-Unesco (1974) ver only the FAO-Unesco soil map of the world Legend and its modification to fit into the Kenya ions (Kenyan Concepts, van der Pouw et al 19..) is explained in this section.

Is

are strongly weathered and leached soils with ABC horizon sequence. They are very deep that the paren al was not reached in the profiles which were made in the area. An ochric, umbric or mollic epipedoi ; an argillic horizon which has a gradual clay bulge with percentage clay not decreasing by more thai om it maximum within 150 cm from the surface. It has shiny ped faces on at least some of the peds ant intly blocky structure. The aggregate stability is high, silt/clay ratio low, and percentage clay is more )% throughout. The base saturation is usually less than 50% and the CEC-clay is about than 24 meq/10C ating presence of low activity clay.

il forming processes which can be inferred from the characteristics described are leaching weathering, cation .translocation of clay (illuviation) and biological homogenization. Ferrugenization is also indicated red colours.

100 dosols sse are young soils developed on volcanic ashes. They have an ABC horizon sequence with a mc brie or ochric epipedon overlying a cambic B horizon. The bulk density is low (< 0.85 g/cm3 at 1/3 1 the consistence on wetting is thixotropic. The exchange complex is dominated by amorphous minerals : allophane and halloysite. The texture is silt loam to loam and the silt/clay ratio is higher than 5 espec the lower parts of the B horizon. s soil forming process which are depicted in the profiles are colour and structure development by si athering and low biological homogenization. Slight translocation of the organic matter is indicated by •wn colour in the B horizon. mbisols

2se are similar to the Andosols in most properties but they may be developed on different type of pa terial. The bulk density is not usually low and the exchange complex is not dominated by the amorp] ïerals. No soil forming processes can be inferred expect some indication of weathering and homogenizal stric, eutric and gleyic subunits occur in the area and have low base saturation ( < 50%), high base satura 50%) and hydromorphic properties respectively. risols

;se are strongly weathered and leached soils with an ABC horizon sequence. An ochric, mollic or um pedon overlies an argillic horizon which has a base saturation of less than 50%. The dominant clay mine kaolinite but the presence of illite can not be excluded. i soil forming processes depicted are weathering, leaching and desaturation of the bases, illuvial ilification, ferrugenization and moderate biological homogenization. The following subunits are found ii a: mic Acrisols - Acrisols with a humic epipedon. Tic Acrisols -Acrisols showing ferric properties. romic Acrisols - Acrisols with red colours, with hues redder than 5YR. ral-chromic Acrisols - like chromic acrisols but showing ferralic properties. :yic Acrisols - Acrisols showing hydromorphic properties with 50 cm from the surface. visols

îse are moderately weathered soil with an ABC horizon sequence. An ochric or umbric epipedon ove argillic horizon which has a base saturation which is higher than 50% throughout. A sharp clay increase >th is usually observed. The texture may vary considerably but is finer than loamy sand. The dominant ining processes are weathering, illuviation, desilification in the AB horizon and biological homogenizat romic, calcicand orthic subunit occur in the are. The chromic ones have red colours with hues redder R and the calcic ones have accumulations of soft powdery lime or calcic horizon within 100cm from face.

101 alsols

se are very strongly weathered soils with an ABC horizon sequence. An ochric epipedon overlies an c orizon. The structure is usually massive and the horizon boundaries are diffuse. The CEC-clay is usu; ' low (< 10 meq/100g) indicating low activity clay. They are strongly leached and the exchange comp jminated by aluminum ion. The aggregate stability is low. There are no Ferralsols sensu stricto in the a an intergrade of the ferralsols and the acrisols hence called, Acri-rhodic Ferralsols. The soil form :esses which may be considered active in the profiles described are biological homogenization . lification. Decalcification, leaching weathering and illuviation have also taken place in the past but n i leached the maximum.

osols and Lithosols

se are generally shallow soils with an AC or AR horizon sequence and very little soil development. r: )Sols have depth limitation by continuous coherent hard rock within 25 cm. The soils have hardly ilopment of the B- horizon and no soil forming processes can be depicted.

tiosols

se are coarse textured soils usually with AC horizon sequence. They are developed on reworked mate ch is resistant to weathering. On leaching, some degree of weathering can be depicted in the soil profi se soils have limited occurrence in the area.

eozems

se are soils with a mollic epipedon. In this area they have an ABC horizon sequence although it is n< lirement that they should have that sequence. The mollic epipedon overlies an argillic horizon. They si ic properties in the subsoil. The dominant soil forming processes in this area on these soils are weathei illuviation. Leaching and desaturation may be taking place but are not very pronounced. These soils > limited in occurrence in the area.

tisols

se are young, heavy clay,cracking, swelling and shrinking soils. They have predominantly montmorillo ' minerals which swell on wetting and shrink on drying hence causing cracking. They have stror eloped slickensides which are intersecting. The dominant soil forming processes are swelling and shrinl< sing pedoturbation, illuviation, weathering and decalcification of the A and B horizons only.

ysols

se are young poorly drained soils showing hydromorphic properties within 50 cm from the surface. T e an AC horizon sequence and no distinct diagnostic horizon.

102 .3 Soil genesis aspects

: basis of soil classification is provided by a combination of soil forming processes and soil forming fact : soil forming factors and the resulting soil forming processes in Chuka-Nkubu area are briefly expia' his section. These have some similarities with the adjacent areas such as Kindaruma area (van de Weg >uvi 1975).

Climate mate is one of the 'zonal' soil forming factors. Rainfall, temperature and humidity which are climatic fac w a strong East-West gradient in this area. The western part of the area is relatively humid and itively low temperatures. Therefore the rate of decomposition of the organic matter is low and the soils >ngly leached and eluviated. This gives rise to humic topsoil, acid soils and low base saturation. Conver eastern part of the area is dry and temperatures are high. Hence the rate of decomposition of the org tter is high and the soils are not strongly leached except in areas where the effect of past climatic condit trongly shown. This is very evident in the area just east of mitunguu where alternating wet and dry clii ulted in the formation of the pisoferric material (murram).

Parent material

ï influence of the parent material on soil genesis is very well shown in the area. The north-western paj area consists of volcanic ashes. This has resulted to soils with low bulk density, thixotropic properties h hydrous minerals such has allophanes. Consolidated pyroclastic and intermediate volcanic rocks, w; rather easily weathered, occurring in the central and the southern part of the area have given ris mgly weathered soils with acid topsoil and quite strong structure. The basic rocks which have n itherable minerals give rise to deep weathered soils also with very good physical properties. The Baser ;tem rocks have a high content of acid minerals such as quartz, feldspars and ferro-magnesium minerals ; hornblende and amphiboles. These rocks are resistant to weathering and hence soils which are shallow ikly weathered are common in the area. The soils are decalcified in the top but concentration of calc bund in the subsoil in some places.

Topography id form and the drainage conditions of the soils are very related soil forming factors. The major landfc not show a strong influence on the soils. However due to the very high slopes in the mountains, hills îor scarps, the soils are excessively drained to well drained. Also the soils of the footridges and the upl; all well drained due to the high and long slopes. The soils on the valleys sides of the footridges she her degree of leaching than those at the crests of the interfluves. On the other hand soils of the bottoml; l flat river valleys are poorly drained to imperfectly drained due to the flat and concave landforms.

103 Biological activity

: of the agents of the biological soil forming factors is man. In the Eastern part of the area where popula sity is high and land cultivation is intensive, the topsoil has been affected, in some areas the humic top been lost while in other areas various artifacts such as charcoal and pottery remnants are found. In tern part of the area where shifting cultivation is practiced and overgrazing is rampant, the organic ma lie topsoil is very low leading to strong surface crusting and sealing. re are different species of soil fauna in the area. However the most important are the termites of diffe ;ies depending on the climatic conditions. The soil fauna activity was found to increase from West to E se have caused soil homogenization, high porosity and high rate of decomposition of the organic matte soil in the Eastern part of the area. The termites excretions were found to have higher C/N ratio and lo 2 than the rest of the soil indicating the unfavorable effect of the soil fauna by depleting the nitrogen litating the leaching of the soil

combination of these soil forming factors and soil forming processes have resulted in a West-East seque oils as follows: losols and Cambisols - Nitisols and Acrisols - Acrisols and Luvisols - Luvisols and Cambisols - Cambi Regosols and Lithosols. Other soil occurring due to local differences in topography and drainage conditi the Vertisols and the Gleysols.

Age

: is the time the soil has been forming. It may therefore be taken as the age of the parent material ex< :ases where past climate caused a total removal of the soil and a new soil started to form later on. ngest parent material in this area is the volcanic ashes. Here young soils have been formed, Other rec erial are colluvium and alluvium found in the bottomland and some river valleys. Here also young soils ad. The oldest parent materials are the Basement System rocks. But due to climate and their resistanc« ithering the soils have no indications of being very old. The most strongly weathered soils are found in i with volcanic rocks due to the influence of climate and relief.

Soil fertility aspects

: appraisal of the soil fertility in the area has been done from chemical data only. The rating of the soi] narily based on chemical characteristics in the top 20-30cm. The details of this rating are given in 1 Tnal Communication No.7 (Kenya Soil Survey, 1977). Considerable variation in soil chemical/phys racteristics may be expected within one soil mapping unit in view of the fact that the data are derived fi connaissance survey at scale 1:100,000. The averaged data for one soil mapping unit may therefore no lificantly different from that of other soil mapping units. The comments below are meant to indicate gen lencies only. A follow-up is therefore necessary. Future greenhouse pot-testing and field fertilizer trials erent crops, on the now identified major soils is expected to yield more substantive data, which can 1 translated into recommendations to the fanners of the area.

104 st readily available plant nutrients are stored in the soil organic matter. Most of the soil types in the sui t have low amounts of organic matter. The percent organic C varies from 0.2-3.2. The other important racteristics with respect to fertility are the cation exchange capacity (CEC) and the base saturation. M s have low CEC values in the top soil. The range of CEC values is from 14-47 me/100g soil.

Is with CEC values in the topsoil in excess of 24 me/100g soil include soils of mapping units RIVp (Hu Josols); RIPr, R2prl, LdBr, UIBr, U2VC, VIXrp, BPC, R3Br and R2Vr (Humic, Mollic, Umbric 5tric Nitisols); LnPr, HIP and U1PC (Humic and Ferric Acrisols); R3Ip (Humic Cambisols); BXd (pi tisols) and V2Pr (Plinthic Gleysols). Base saturation also varies but most of the mapping units have lo ii 50%. Most of the soils in the survey area are adequately supplied with basic plant nutrients viz. Ca, K. this particular report, however, average values are given for available Ca, K, Mg and P. The labora üts for fertility evaluation show that most of the composite soil samples come from moderately weathi Is. The available phosphorus and nitrogen are low especially in the eastern part of the survey area. 1 e also low CEC and high pH values. In view of the low N and P levels which are required for plant gro^ s imperative that N and P fertilizers should be applied in rates required for satisfactory crop productie

Land management aspects an be realized that the physical aspects of the soils in the eastern part of the survey area are unfavoura -;y have low infiltration rates, poor aeration and high erodibility. All these conditions are related to a ictural stability.

:ir low percolation rates require a very high level of soil management because it increases their susceptib alinisation and probably to sodification. Without proper management, the Exchangeable Sodium Percen JP) of these soils, with their low CEC values, can increase to levels at which clay peptises, leading ther decrease in structural stability. When these soils are opened up for cultivation, careful manager 'uld be adhered to. t soils in the western part of the survey area have more favourable soil physical conditions. They ha itively moderate organic matter which leads to a more stable structure and leads to good water entry i I better aeration. However, they also require careful soil management options which will lead to more st icture.

105 I

I SELECTED SOIL CHARACTERISTICS AND QUALITIES the legend, the descriptions of the mapping units are followed by ratings, in tabular format, of 11 soil taracteristics and qualities. These are: Drainage (Dra) I Effective soil depth (Dep) Inherent fertility (Fer) Salinity (Sa) I Sodicity (So) Stoniness/Boulders (SB) Rockiness (Ro) I Consistence (Co) Moisture storage capacity (Msc) Infiltration capacity (In) I Excess surface water (Ew)

Bhe rating classes for these characteristics and qualities are partly based on rating tables that are derived from "Proposals for Ratings of Land Qualities" by KSS (1977). The rating classes and their ranges are given below. he ratings shown in the legend, following the mapping unit descriptions, refer to the main soil of the :spective map units. Characteristics of inclusions have been weighed in these ratings only if they comprise Sover 30% of the map unit, i.e. if in the description the phrase "in many places" is used.

•oil drainage classes (Dra)

excessively and somewhat excessively drained I well drained 3. moderately well drained imperfectly drained K poorly and very poorly drained Ijffectiv e soil depth (Pep) Depth to hard or very concretionary, root impending layers: rocks, weathering rock, petroplinthite and îtrocalcic material (as in pisoferric and pisocalcic phases), including "planic" (abrupt) textural changes (in f lanosols only) extremely deep > 180 cm ! very deep 120 - 180 cm deep 80 - 120 cm moderately deep 50 - 80 cm i shallow 25 - 50 cm very shallow 0 - 25 cm

106 !

Inherent fertility (Fer")

The rating components for "Chemical soil fertility" according to the KSS are: CEC, available nutrients and mineral reserve. As, for the present survey, insufficient analytical data are available for rating according to the KSS system, and therefore a simplified rating system is applied here, based on soil classification criteria mainly. It should be noted that the ratings arrived at, refer to broad inherent fertility classes only. They should not be used for the assessment of fertilizer requirements. The latter can only be carried out on basis of field trials. The inherent fertility ratings refer to topsoil characteristics (0-25 cm).

1 high : three of the following criteria are met: CEC >24 me/100g clay and fine textural class* BS >50% OM >1.5% rich parent rock 2 moderate : two of the following criteria are met: CEC > 16 me/100 g clay and either: medium or fine textural class* or : OM >1.5% BS >50% moderately rich or rich parent rock

3 low : two of the following criteria are met: CEC < 16 me/100 g clay and medium or fine textural class* BS <50% OM <1.5% 4 very low : all of the following criteria are met: CEC < 16 me/100 g clay and coarse textural class* BS <50% OM <1.5% poor parent rock

Note: downgrade by 2 classes for Solonetz and Solonchaks and for saline and/or sodic phases

* Textural classes according to FAO-Unesco (1974).

Salinity (Sa)

0 non saline : ECe <4 mmhos/cm throughout profile

1 slightly saline ECe 4-8 mmhos/cm within 80 cm -j | saline phase 2 saline ECe > 8 mmhos/cm within 80 cm J

107 Sodicitv (So)

0 non sodic ESP <6% throughout profile

1 slightly sodic ESP 6-15% within 80 cm -, | sodic phase 2 sodic ESP >15% within 80 cm -J

Stoniness. Boulders (SB)

Loose mineral fragments; stones: 7.5 - 25 cm diameter.; boulders: more than 25 cm diameter.

0 non stony non bouldery 0 - 2% by volume

1 slightly stony slightly bouldery 2 - 15%

2 stony bouldery 15 - 50% -, | stony/bouldery phase 3 very stony very bouldery >50% -I

Rockiness (Ro)

Outcrops of solid rock at soil surface

0 non rocky 0- 2% of area consists of bedrock

1 fairly rocky 2- 10%

2 rocky 10-- 25% -, 1 1 3 very rocky 25 --50% | rocky phase 1 4 extremely rocky 50-- 90% -I

Consistence (Co)

Moist consistence of the subsoil; rated according to FAO (1977)

1 half ripe 2 loose 3 very friable 4 friable 5 firm 6 very firm

108 not rated (shallow and very shallow soils)

Moisture storage capacity (Msc)

Available moisture; estimated over effective soil depth

1 very high > 160 mm 2 high 120 - 160 mm 3 moderate 80 - 120 mm 4 low < 80 mm

Note: downgrade by one class for strongly stratified soils (Fluvisols) downgrade by two classes for Solonetz and for sodic phases

Infiltration capacity (In)

Maximum amount of water infiltrating into the dry soil, per unit of time and per unit of area; estimated on basis of soil texture, soil depth, stoniness, boulders and cracking properties; ranges according to Israelsen and Hansen (1962), adapted.

1 high > 2.5 cm/hr 2 medium 0.5 - 2.5 cm/hr 3 low < 0.5 cm/hr

Note: downgrade by one class for Planosols, Solonetz and for sodic phases

Excess surface water (Ew)

0 none 1 seasonal flooding (flooding refers to superficial passage of water originating from areas outside the terrain concerned; it is usually accompanied by scouring and sedimentation) 2 seasonal ponding (ponding refers to the accumulation of water in and on the terrain concerned due to its relatively low and flat position) 3 permanently waterlogged

109 5. ACKNOWLEDGEMENTS

The authors would like to acknowledge the following persons and institutions.

1. Kenya Soil Survey staff: P.N. Macharia, N.P. Ochieng and KSS laboratory staff, T.J. Wachira, and S.W. Wataka.

2. Senior Soil Chemist and his staff (NARL).

3. All the Section Heads in Meru District and their staff.

4. E.W. Maina for typing the report.

110 REFERENCES

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Braun, H.M.H., unpublished. Evaporation in Kenya. Kenya Soil Survey, Nairobi.

Braun, H.M.H., 1977. Proposals for rating of land qualities - 2nd approximation.International Communication (I.C.) No. 7 (S472). Kenya Soil Survey, Nairobi.

Black,C.A., 1965. Methods of soils analysis. Agronomy No. 19, Am. Soc. of Agron., Inc.

Bogdan, A. V. 1958. A Revised List of Kenya Grasses, Gov. Printer, Nairobi.

Chief Geologist, 1967. Geological Map of Kenya Mines and Geological Dept. Nairobi.

Clayton, W.D. 1974, C.E Hubbard and S.A. Renvoize. Gramineae Part 1 and 2. In: Flora of Tropical East Africa.

Dale, R.I. and Greenway, P.J., 1961. Kenya Trees and Shrubs. Buchanan's Kenya Estates Ltd Nairobi.

Day, R.P., 1956. Report of the committee on physical analysis 1954-1955. Soil Sei. Soc. Am. Proceedings, 20:167-169.

Dodson, R. 1953. Geology of the south-east Machakos area (with coloured map, scale 1:25,000).Report No. 25. Geological Survey of Kenya, Nairobi.

Dombois, D.M. and H. Ellenberg. 1974. Aims and Methods of Vegetation Ecology.

E.A.M.D., 1970. Temperature data for stations in East Africa; Part I, Kenya. E.A.M.D, Nairobi.

FAO, Guidelines for soil description. FAO, Rome, 1967.

Food Agriculture Organization 1974. Tree Planting Practices in African Savannas, F.A.O. Rome, 1974.

FAO/UNESCO, 1974. Soil Map of the World 1:5M vol. 1 the Legend. World Soil Resources Report 60, FAO, Rome.

Gachene, C.K.K., 1987. Semi-detailed soil survey of the Evurore catchment area (Embu District). Report S14. Kenya Soil Survey, Nairobi.

111 Gethin-Jones, G.H. and Scott, R.M., 1959. Soil Map of Kenya (scale 1:3,000,000). In: Survey of (Kenya (ed), 1970, National Atlas of Kenya (3rd ed.). Govt, of Kenya.

Hinga, G., Muchena, F.N., and Njihia, CM., 1980. Physical and Chemical methods of Soil analysis. Ministry of Agriculture, National Agricultural Labs., Nairobi.

Houba, V.J.G., J. Ch. van Schouwenburg & I. Wallinga, 1979. Methods of analysis of soils. Msc-course in Soil Science and Watermanagement. Department of Soil Science and Geology, Agricultural University, Wageningen, The Netherlands.

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Jaeztold R. and Schmidt, H., 1983. Farm Management Handbook of Vol.11. Ministry of Agriculture, Nairobi.

K.M.D., 1984. Climatological Statistics for Kenya; K.M.D., Nairobi.

K.M.D., 1993. Summary of rainfall in Kenya; K.M.D., Nairobi.

KSS, 1977. Ratings of land qualities in Kenya 2rd approximation Kenya Soil Survey Nairobi

Legger, D., van der Pouw, B.J.A., 1980, The Fertility Appraisal of the Soils in the Amboseli- Kibwezi area, Kenya. Fourth Annual General Meeting of the S.S.S. of East Africa, 1980, Arusha, Tanzania.

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113 APPENDIX 5

LEGEND AND RATING TABLES

M MOUNTAINS (relief intensity Dra

over 300m, slopes over 30%)

MQ Soils developed on granitoid gneisse and migmatites

MQC complex of somewhat 1 1-5 excessively drained to well drained, reddish brown to brown soils of varying depth, consistence, rockiness, stoniness and texture (LITHOSOLS, eutric REGOSOLS, eutric CAMBISOLS and orthic LUVISOLS, partly lithic and stony phases)

MB Soils developed on gabbro-norites

MBP somewhat excessively drained, 1 5 shallow to moderately deep, dark reddish brown, friable, rocky and stony sandy loam to clay loam (LITHOSOLS and eutric REGOSOLS, partly lithic and stony phase)

H HILLS AND MINOR SCARPS (relief intensity 100-300m, slopes 8-30%)

HQ Soils developed on granitoid gneisses and migmatites

HQC complex of somewhat 1 5 excessively drained, dark reddish brown to strong brown, friable soils of varying depth, rockiness, stoniness and texture (LITHOSOLS, eutric REGOSOLS, eutric CAMBISOLS and chromic LUVISOLS; partly lithic and stony phases)

HG Soils developed on granites

HGP well drained, shallow to 2 5 moderately deep, red to dark reddish brown, friable, clay loam to clay; in places fairly rocky and stony (dystric CAMBISOLS and humic ACRISOLS; partly petroferric and stony phases) HU Soils developed on undifferentiated metamorphic rocks (mainly gneisses)

HUC complex of well drained, 2 dark reddish brown to brown, gravelly soils of varying depth, consistence, rockiness, stoniness and texture {LITHOSOLS, eutric REGOSOLS and eutric and dystric CAMBISOLS; partly lithic and stony phases)

HB Soils developed on gabbros, gabbro-norites and basalts

HBP1 somewhat excessively 1 drained, shallow, dark red to dark reddish brown, rocky, stony, sandy clay loam to clay (LITHOSOLS and eutric CAMBISOLS, lithic and stony phases)

HBP2 well drained, shallow to 2 moderately deep, dark yellowish brown, friable, clay loam to clay; in places rocky and stony.

HBC complex of somewhat 2 excessively drained, shallow to moderately deep, dark reddish brown, friable, sandy clay loam to clay; in places, fairly rocky and stony (LITHISOLS, eutric and calcaric REGOSOLS; lithic and partly stony phases)

HI Soils developed on nepheline phonolites

Hip well drained, moderately 2 deep to deep, red to dark reddish brown, friable, sandy clay loam to clay; in places fairly rocky and stony (dystric CAMBISOLS and chromic* ACRISOLS; partly stony phase)

HP Soils developed on consolidated pyroclastic rocks (lahar conplex) HPC Complex of well drained, 2 1-6 3 0 0 0 0 4 1-4 1 0 dark red to brown, friable clay soils of varying depth; with acid humic topsoil (chromic and orthic ACRISOLS; partly lithic phase)

HV Soils developed on various volcanic rocks

HVP well drained, shallow, dark 2 5 2-30031410 reddish brown, fairly rocky and very stony, gravelly, clay loam to clay (LITHISOLS and eutric REGOSOLS, partly stony phase)

R FOOTRIDGES

R1 MOUNT KENYA FOREST LEVEL (relief intensity 80-200m), slopes 10-30% altitude over 2000m)

R1P Soils developed on pyroclastic rocks (lahar complex, tuffs and volcanic ashes)

R1PC complex of well drained, 2 2-3 1 0 0 0 0 4 2-3 10 deep to very deep, dark yellowish brown to brown, friable, silty clay loam to clay; in places smeary (dystric and ando-cumulic NITISOLS*, humic ANDOSOLS and humic CAMBISOLS)

R1V Soils developed on various volcanic rocks (mainly volcanic ashes and basalts of Mt. Kenya series)

R1VP well drained, moderately 2 3-4 2 0 0 00 4 4 1 0 deep to deep, dark yellowish brown to brown, friable, loam to clay loam, with 20-30 cm acid humic topsoil; in places smeary (humic CAMBISOLS and humic ANDOSOLS; partly lithic phase)

R2 KIONYO LEVEL (relief intensity 30-100m, slopes 3-30%, altitude 1600-2000m)

116 R2P Soils developed on pyroclastic rocks (lahar complex, volcanic ashes and tuffs)

R2Pr1 well drained, very deep, 2 2 dark red to dark reddish brown, friable clay; with 20-30cm humic topsoil (humicNITISOLS*)

R2Pr2 well drained, deep to very 2 2- deep, red to dark reddish brown, friable clay; in places with 20-30cm humic topsoil (humic NITISOLS* and orthic ACRISOLS)

R2Pb well drained, deep to very 2 2- deep,yellowish red to dark brown, friable and smeary, loam to clay loam; with 20-30cm acid humic topsoil (humic ANDOSOLS)

R2Pbp well drained, moderately 2 3- deep to deep, dark yellowish brown to dark brown, friable, silt loam to clay loam; with 20-30cm acid humic topsoil; in places fairly rocky and stony or smeary (humic ANDOSOLS and humic CAMBISOLS, partly stony phase)

R2V Soils developed on various volcanic rocks (mainly tuffs and nepheline phonolites)

R2Vr well drained, very deep, 2 2 red to dark reddish brown, friable to firm clay (dystric NITISOLS»)

R3 CHOGORIA LEVEL (relief intensity 10-80m, slopes 5-25%, altitude 1200-1 700m)

R3B Soils developed on basalts of Mt. Kenya series

R3Br well drained, very deep, 2 2 red to dark reddish brown, friable to firm clay; with about 20cm acid humic topsoil (dystric and humic NITISOLS»)

R3I Soils developed on nepheline phonolites R2lr well drained, very deep, 2 2 2-3 0 0 0 0 4-5 11 0 red to dark reddish brown, friable to firm clay; with about 20cm humic topsoil (humic NITISOLS*)

R3IP well drained, shallow to 2 4-5 2-3 0 0 2 14 4 10 moderately deep, dark reddish brown, fairly rocky and stony, gravelly clay (humic CAMBISOLS, partly stony phase and LITHOSOLS)

R3P Soils developed on consolidated pyroclastic rocks (lahar complex)

R3Pr1 well drained, very deep, 2 2 2-3 0 0 0 0 4 110 dark red to dark reddish brown, friable clay; with humic topsoil (humic NITISOLS*)

R3Pr2 well drained, deep to very 2 2-3 2-4 0 0 0 0 4 1-2 1 0 deep, dark reddish brown, friable clay; in places with about 20cm humic topsoil (humic NITISOLS* and orthic ACRISOLS)

R3V Soils developed on various volcanic rocks

R3Vr well drained, very deep, 2 2 2-3 0 0 0 0 4-51 1 0 dark red, friable to firm clay; with about 20cm of humic topsoil (humic NITISOLS*)

F FOOTSLOPES (relief intensity less than 100m, slopes over 100%)

FU Soils developed on undifferentiated metamorphic rocks

FUP well drained, shallow 2 4-5 2 0 0 2 2 4 4 10 to moderately deep, red to dark reddish brown, friable, sandy loam to sandy clay loam; in places rocky and stony (LITHOSOLS and chromic CAMBISOLS, partly lithic and stony phases)

118 FUp well drained to moderately 2-3 3-4 3-4 0 0 0 0 2-4410 well drained, moderately deep to deep, dark reddish brown to dark brown, loose to friable, sand to sandy clay loam (eutric CAMBISOLS and albic ARENOSOLS)

FV Soils developed on various volcanic rocks

FVp well drained, moderately 2 3-4 2 O 0 2 1 4 2-3 1 0 deep to deep, reddish brown, friable, clay loam to clay; in places fairly rocky and stony (eutric REGOSOLS and chromic CAMBISOLS, partly stony phase)

FX Soils developed on various

rocks

complex of: 0 2 2 4 4 1 0 -somewhat excessively 1 4-5 1 0 drained, shallow to moderately deep, dark red to dark reddish brown, friable sandy clay loam; in places rocky and stony (LITHOSOLS and chromic CAMBISOLS; partly lithic and stony phases) -somewhat excessively 15 10 0 0 0 4 4 1 0 drained, shallow, dark red to dark reddish brown, friable, clay loam to clay (eutric REGOSOLS and chromic and humic CAMBISOLS, lithic phase)

well drained, moderately 2 3-4 2 0 0 1 1 4 2-3 1 0 deep to deep, very dark brown, friable clay; in places slightly rocky and slightly stony (humic CAMBISOLS, stony phase)

P PLATEAUS

Ln NON-DISSECTED PLATEAUS (relief intensity less than 50m, slopes 0-8%).

Lnl Soils developed on nepheline phonolites

119 LnIC complex of well drained, 2 1-6 dark reddish brown, friable, very gravelly, sandy clay loam to sandy clay soils of varying depth, rockiness and stoniness (dystric CAMBISOLS and LITHOSOLS; stony phase)

LnP Soils developed on consolidated pyroclastic rocks

LnPr well drained to moderately 2-3 2 well drained, very deep, dark reddish brown, friable clay (humic, chromic* and ferric ACRISOLS)

LnPC complex of excessively 1 1-6 drained, dark reddish brown to brown, very gravelly, sandy clay loam to sandy clay soils of varying depth, consistence, rockiness and stoniness (dystric CAMBISOLS, pisoferric and partly lithic and stony phases and LITHOSOLS)

Ld DISSECTED PLATEAUS (relief intensity less than 30m, slopes 0-12%)

LdB Soils developed on basalts of Mt. Kenya series

LdBr well drained, deep to 2 2-3 very deep, red to dark reddish brown, friable to firm, clay loam to clay; in places stony and gravelly (humic NITISOLS and ferric ACRISOLS; partly pisoferric phase)

LdV Soils developed on various volcanic rocks

LdVr well drained, deep to 2 2-3 very deep, dark reddish brown, friable to firm clay; (luvic PHAEOZEMS and mollic NITISOLS*)

U UPLANDS IM HIGH LEVEL (relief 2 intensity less than 50m, slopes 0-16%, altitude over 900m)

(JIB Soils developed on basalt of Mt. Kenya series

U1Br well drained, very deep, 2 yellowish red to dark brown, friable to firm clay (mollic NITISOLS*)

U1P Soils developed on consolidated pyroclastic rocks

U1PC complex of somewhat 1-2 excessively drained to well drained, dark reddish brown to brown, gravelly sandy clay soils of varying, depth, consistence, rockiness and stoniness (LITHOSOLS, ferric ACRISOLS and dystric CAMBISOLS, partly lithic and stony phases)

U1V Soils developed on various volcanic rocks

U1Vr well drained, very deep, 2 dark red to dark reddish brown, friable to firm clay; in places with 20-30cm humic topsoil (mollic and humic NITISOLS*)

U1VrP well drained, shallow to 2 moderately deep, dark red to dark reddish brown, friable, sandy clay loam to clay (luvic and haplic PHAEOZEMS, chromic ACRISOLS and dystric CAMBISOLS; partly lithic phase)

U1X Soils developed on various rocks

U1XrP well drained, moderately 2 deep, yellowish red to dark reddish brown, friable, sandy clay loam to sandy clay, in places rocky and stony'(ferric ACRISOLS, and chromic LUVISOLS; stony phases) U2 LOW LEVEL (relief intensity less than 50m, slopes 0-16%, altitudes less than 900m)

U2Q Soils developed on . granitoid gneisses and migmatites

U2Qp well drained, moderately 2430000441 0 deep, dark reddish brown, friable, gravelly, clay loam to sandy clay (chromic LUVISOLS, partly lithic phase)

U2QP well drained, shallow, dark 25 2-3 000244 10 reddish brown, stony and gravelly, clay loam to clay; in places rocky (chromic LUVISOLS, stony phase and partly lithic phase and LITHOSOLS)

U2QC complex of:

-well drained, moderately 2430021 4 3-4 1 0 deep to deep, red to dark reddish brown, fairly rocky and stony, gravelly, clay loam to clay (orthic and chromic LUVISOLS, lithic and stony phase)

-well drained, shallow to 2 4-53002-31 44 1 0 moderately deep, red to dark reddish brown, rocky to very rocky, stony to very stony, gravelly, sandy clay loam to clay (eutric REGOSOLS and orthic LUVISOLS, lithic and stony phase)

U2F Soils developed on hornblende and biotite gneisses

U2Fr well drained, deep to very 2 2-33000042-310 deep, dark red to dark reddish brown, friable, sandy clay to clay; in places gravelly (orthic and chromic LUVISOLS)

U2Frp well drained, moderately 2430022 4-54 10 deep dark red to dark brown, friable to firm, sandy clay loam to clay; in places rocky, stony, gravelly and/or calcareous (orthic and chromic LUVISOLS and calcic CAMBISOLS; partly petroferric, lithic and stony phases)

122 U2FC complex of:

-well drained, moderately 2 3-43002142-410 deep to deep, dark red to dark reddish brown, friable, clay loam to clay; in places fairly rocky and stony (orthic and chromic LUVISOLS, partly stony phase)

-well drained, moderately 2 3-4 2-3 0 0 0 0 4-5 3-4 1 0 deep to deep, dark red to dark reddish brown, friable to firm clay loam to clay; in places over pisoferric or pisocalcic material (orthic, chromic and calcic LUVISOLS, partly pisocalcic phase and ferric ACRISOLS, pisoferric phase)

-well drained, shallow to 2 4-5 2-3 0 0 2-3 2-3 4 2-4 1 0 moderately deep, dark red to strong brown, gravelly, clay loam to clay; in places rocky to very rocky and stony to very stony (eutric CAMBISOLS and orthic LUVISOLS, partly lithic and stony phases and LITHOSOLS)

U2U Soils developed on undifferentiated metamorphic rocks

U2Urp well drained, moderately 2 3-4 3 0 0 1-2 2 4 3-4 1 0 deep to deep, red to reddish brown, friable, slightly rocky to rocky, stony, sandy clay (chromic LUVISOLS, partly lithic and stony phases)

U2UC complex of;

-well drained, deep, red to 2 3 4 0 0 1 0 4 3-4 1 0 dark reddish brown, friable slightly rocky, slightly stony, clay loam to clay (chromic LUVISOLS)

-well drained, moderately 2 3-4300214-5410 deep to deep, red to dark reddish brown, friable to firm, fairly rocky, stony, gravelly, clay loam to clay; in places over pisocalcic material (chromic and chromo»- calcic LUVISOLS, stony and partly pisocalcic phases)

123 -well drained, shallow, dark 2 5 3 0 0 3 3 4 4 10 reddish brown, friable, very rocky, very stony, gravelly, sandy loam to sandy clay loam (LITHOSOLS, and eutric and dystric REGOSOLS, lithic and stony phases)

U2Qp well drained, moderately 2 4 3 0 0 0 0 4 4 1 0 deep, dark reddish brown, friable, gravelly, clay loam to sandy clay (chromic LUVISOLS, partly lithic phase)

U2B Soils developed on basalts of Mt. IMyambene series

U2Br1 well drained, very deep, 2 2 2 0 0 0 0 4 1 10 red to dark reddish brown, friable clay (mollic NITISOLS*)

U2Br2 well drained, very deep, 2 2 3-4 0 0 0 0 4 1-4.1 0 dusky red to dark reddish brown, friable, clay loam to clay (ACRI-rhodic FERRALSOLS)

U2BP well drained, shallow to 2 4-5 3 0 0 0 0 4 3-41 0 moderately deep, dark reddish brown to dark brown, friable, gravelly, clay loam to clay (chromic and eutric CAMBISOLS, partly lithic or pisoferric phase)

U2X Soils developed on various rocks

U2Xrp well drained, moderately 2 3-4 2 0 0 0 0 4 4 1 0 deep, red to dark red, friable, clay loam to clay (chromic LUVISOLS, petric phase)

U2XA association of

-soils of unt U2Xrp 2 3-4 2 0 0 0 0 4 4-51 0 well drained, moderately deep to deep, dark reddish brown to dark greyish brown, calcareous, friable to firm, slightly gravelly, sandy clay to clay (vertic and calcic LUVISOLS)

124 U2XC complex of:

-well drained, moderately 2 3 deep to deep, red to dark reddish brown, friable, slightly rocky, stony, clay loam to clay (chromic LUVISOLS and orthic ACRISOLS. stony phase)

-well drained, shallow, 2 5 dark reddish brown, bouldery, very stony, gravelly, sandy loam to clay loam; in places over petroplinthite (murram) (eutric REGOSOLS and dystric and eutric CAMBISOLS; partly lithic, petroferric and stony phases)

P PLAINS

Pn NON-DISSECTED PLAINS (relief intensity less than 10m, slopes 0-2%)

PnB Soils developed on basalts of Mt. Kenya and Nyambene series

PnBrl well drained, very 2 2 deep, red to reddish brown friable clay (humic and dystric NITISOLS»)

PnBr2 well drained, very deep, 2 2 dusky red to dark reddish brown, friable, clay loam to clay (ACRI-rhodic FERRALSOLS)

PnBrP well drained, moderately 2 3 deep to deep, dark red to dark reddish brown, friable, gravelly, clay loam to clay; over pisoferric material (murram) (chromic ACRISOLS, pisoferric and patrie phases)

PnBbPI well drained, shallow to 2 4 moderately deep, brown to dark greyish brown, friable, clay loam to clay, over pisoferric material or petroplinthite (murram) (orthic ACRISOLS and ferrie CAMBISOLS, pisoferric phase and partly lithic or petroferric phases)

PnBbP2 well drained, shallow, 2530000441 0 dark reddish brown to very dark brown, gravelly, clay loam to clay; over pisoferric material (murram) dystric and chromic CAMBISOLS and eutric REGOSOLS; petric, lithic and pisoferric phases)

PnBrl - association of:

PnBbP2 - soils of unit PnBrl 2 4-5 3000044 10 - soils of unit PnBbP2 v PnP Soils developed on consolidated pyroclastic rocks (lahar complex)

-well drained, dark reddish 2 1-6 3 0 0 0 0 4 1-4 1 0 brown to dark brown, rocky, friable, sandy clay soils of varying depth and stoniness (orthic LUVISOLS, partly lithic phase and LITHOSOLS)

PnX Soils developed on various rocks

PnXr well drained deep, dark red, 2230000421 0 friable clay (chromic* ACRISOLS)

PnXr- association of:

PnBbP2 - soils of unit PnXr 2 2-53000042-410 - soils of unit PnBbP2

Pd DISSECTED PLAINS (relief intensity up to 20m,slopes less than 5%)

PdB Soils developed on basalts of Mt. Kenya and Mt. Nyambene series

PdBr well drained, very deep, 2 2 2 0 0 00 4-5 1 1 0 dark reddish brown, friable to firm, clay; with 30-40cm humic topsoil (mollic NITISOLS*)

V VALLEYS

126 V1 MAJOR VALLEYS (relief intensity 50-1 OOm, slopes 8-30%)

V1P Soils developed on consolidated pyroclastic rocks (lahar complex)

V1PC complex of:

-well drained, moderately 2 3-43000043-410 deep to deep, dark reddish brown, friable clay (dystric NITISOLS and humic and chromic* ACRISOLS)

-well drained, shallow to 2 5 3 0 0 1-21-24 3 1 0 moderately deep, dark reddish brown, friable, slightly rocky to rocky, slightly stony to stony clay; in places over petroferric material (murrain) (chromic* ACRISOLS and chromic LUVISOLS, partly petroferric, stony and lithic phases)

V1X Soils developed on various rocks

V1Xrp well drained, moderately 2 3-4300004-51 10 deep to deep, dark red to dark brown, friable to firm clay (humic NITISOLS* and chromic ACRISOLS, partly lithic phase)

V2 MINOR VALLEYS (relief intensify less than 50m, slopes 8-30%)

V2P Soils developed on consolidated pyroclastic rocks (lahar complex and tuffs)

V2Pr well drained, deep to 2 2-3 3 0 0 0 2 4 1 0 1 very deep, dark red to dark reddish brown, friable clay; in places rocky (dystric and humic NITISOLS and humic and plinithic ACRISOLS)

V2PC complex of well drained, 2 1-6 3-4 0 0 0 0 1-61-40 1 dark reddish brown, clay soils of varying depth, consistence, rockiness and stoniness (chromic, ferric and calcic LUVISOLS and chromic ACRISOLS; partly lithic and stony phases and LITHOSOLS)

127 I

2X Soils developed on r various rocks V2XC complex of well drained 2 • to imperfectly drained, H friable soils of varying depth, colour, rockiness, stoniness and texture; in • places mottled (ferric I ACRISOLS, gleyic • CAMBISOLS, eutric FLUVISOLS and LITHOSOLS)

Iß BOTTOMLANDS (relief ME intensify less than 10m, slopes less than 2%

HBP Soils developed on | consolidated pyroclastic rocks (lahar complex)

HBPC complex of:

-imperfectly drained, 4 shallow to moderately H deep,dark brown to dark H greyish brown,friable, gravelly clay loam; in places over pisoferric I material (murram) and I mottled (ferric ACRISOLS, partly pisoferric phase)

H -imperfectly drained to 4 H poorly drained, moderately deep to deep, very dark greyish brown • to black,mottled, friable I to firm, clay loam to clay; in places cracking (plinthic and vertic • GLEYSOLS and pellic I VERTISOLS)

BX Soils developed on • various rocks

* BXd imperfectly drained to 4 poorly drained, moderately m deep to deep, very dark I greyish brown to black, ' firm, calcareous, cracking clay; in places stratified • (pellic VERTISOLS and I eutric FLUVISOLS pisocalcic • phase)

• BXg poorly drained, very deep, 5 I very dark greyish brown, * mottled, friable, clay loam to sandy clay; with • topsoil of un-decomposed I material of varying depth • (chromic ACRISOLS) PROFILE DESCRIPTION NO. 1

Mapping unit MQC Soil classification Orthic Luvisol Agro-climatic zone IV Observation 122/4-114 Local petrography Granitoid gneisses Physiography Mountains Relief macro Rolling to hilly Relief meso/micro Gullies Vegetation/landuse Charcoal burning Overwash/overblow Nil General ground water level Deep Erosion Severe sheet Surface stoniness Stony Rockoutcrops Rocky Flooding Nil Slope gradient 23% Surface crusting Weak Effective soil depth Moderately deep Internal drainage class Somewhat excessively drained

Profile descrptions

Ah 0-1 Ocm dark brown to brown (7.5YR 4/2) moist; sand, slightly gravelly; weak, fine to medium, subangular blocky; soft when dry, very friable when moist, non sticky and non plastic when wet; few fine, few very fine pores; gradual and smooth transition to:

AB 10-20cm dark brown (7.5YR 3/4) moist; sand, slightly gravelly; weak, fine to medium subangular blocky; slightly hard when dry, very friable when moist, non sticky and non plastic when wet; some clay bridging; few fine, few very fine pores; clear and wavy transition to:

Bt 20-40cm reddish brown (5YR 4/4) moist; sandy clay loam, slightly gravelly; weak, fine to medium subangular blocky; slightly hard when dry, friable when moist, slightly sticky and slightly plastic when wet; patchy thin clay skins and clay bridging; few medium, few fine, few very fine pores; clear and wavy transition to:

B + CR 40-60cm reddish brown (5YR 4/4) moist; sandy clay

129 LABORATORY DATA OF PROFILE DESCRIPTION NO. 1 Observation no. 122/4-114 Mapping unit: MQP Soil classification: orthic Luvisol

Laboratory no. /86 2150 2151 2152 2153

Horizon Ah AB Bt B + CR

Depth (cm) 0-10 10-20 20-40 40-60

pH-H20 (1:2.5 w/v) 6.8 6.4 6.1 6.3

pH-KCI " 5.8 5.1 4.8 5.2

EC(mmho/cm) " 0.04 0.03 0.03 0.05

CaC03 (%)

C (%) 0.6 .04 0.4 0.4

N (%) 0.07 0.06

CEC(me/100g), pH 8.2 3.8 3.4 5.8 6.0

Exch. Ca (me/100g) 1.7 1.0 1.8 2.2

" Mg " 0.8 0.7 1.2 1.7 „ „ R 0.5 0.4 0.2 0.1

" Na " 0.1 0.1 0.1 0.1

sum of cations 3.6 2.2 3.3 4.1

Base sat. % ph 8.2 95 65 57 68

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 84 84 78 72

Silt % (0.05-0.02) 7 7 5 7

Clay % (0.02-0mm) 9 9 17 21

Texture class LS LS SL SCL

130 PROFILE DESCRIPTION NO. 2 V Mapping unit HOC Soil classification chromic LUVISOL Agro-climatic zone IV Observation 1 22/4-^(98) Local petrography Gneisses Physiography Hills f^/

Profile descriptions

Ah 0-25cm dark brown (7.5YR 3/2) moist; gravelly and stony loamy sand; moderate, medium granular and crumby; many medium and fine pores; firm when moist, non sticky and non plastic when wet; gradual and wavy transition to:

B + CR 25-60cm dark reddish brown (5YR 3/4) moist; moderate, medium subangular blocky structure; common, medium and fine pores; gravelly and very stony sandy clay loam; firm when moist, slightly sticky and slightly plastic; gradual and irregular transition to:

CR >60cm rock structure

131 LABORATORY DATA OF PROFILE DESCRIPTION NO. 2 Observation no. 122/4-2 Mapping unit: HOP Soil classification: chromic Luvisol

Laboratory no. / 595 596

Horizon Ah B + CR

Depth (cm) 0-25 25-60

pH-H20 (1:2.5 w/v) 7.1 6.4

pH-KCI " 5.9 5.2

EC(mmho/cm) " 0.10 0.04

CaC03 (%)

C (%) 0.9 0.1

N (%)

CEC(me/100g), pH 8.2 10.3 12.9

Exch. Ca (me/100g) 5.4 3.0

" Mg " 2.9 2.8

" K " 0.5 0.2

" Na " 0.4 0.1

sum of cations 9.2 6.1

Base sat. %, pH 8.2 90 50

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 70 66

Silt % (0.05-0.02) 14 8

Clay % (0.02-0mm) 16 26

Texture class SL SCL

132 PROFILE DESCRIPTION NO. 3

Mapping unit HGP Soil classification humic Acrisol Agro-climatic zone IV Observation 122/3-3 (127) Local petrography Granite Physiography Minor scarp Relief macro Hilly Relief meso/micro Gullies Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Slight sheet and ril Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 40% Surface crusting Nil Effective soil depth Very deep Internal drainage class Well drained

Profile descriptions

0-20cm reddish brown (5YR 4/4) moist; sandy clay loam; moderate, fine angular blocky; slightly hard when dry, friable when moist, slightly sticky and slightly plastic when wet; many micro and biopores; many very fine and fine, very few medium and coarse roots; abrupt and smooth transition to:

B1 20-50cm red (2.5YR 4/6) moist; sandy clay; strong fine, angular blocky; hard when dry, friable when moist, slightly sticky and plastic when wet; continous thick clayskins; few macropores and many biopores; not many roots; clear and smooth transition to:

B2 55-120 +cm red (2.5YR 4/8) when moist; slightly gravelly clay, increasingly gravelly with depth; moderate fine, angular angular blocky; hard when dry, friable when moist, slightly sticky and plastic when wet; continous thick clayskins; few macropores and many biopores; not many roots; clear and smooth

133 I I PROFILE DESCRIPTION NO. 4

Mapping unit HUC Soil classification Eutric Regosols 9? (LÙ-SY ctiync ^4^-^ %mffiC IPhysiography Hill / Relief macro Hilly Relief meso/micro Gullies IVegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep IErosion Nil Surface stoniness Nil Rockoutcrops Nil IFlooding Nil Slope gradient 20% • Surface sealing Nil 'Effective soil depth Moderately deep Internal drainage class Well drained I Profile descriptions

I Ah 0-1 Ocm dark reddish brown (5YR 3/2) moist; sandy loam; common, medium distinct yellowish brown mottles (10YR 5/6) moist; slightly gravelly sandy loam; strong fine subangular blocky; friable when moist, non sticky and non plastic when I wet; many medium and fine pores; frequent fine and few medium roots; clear and broken transition to:

I CR/B 10-80cm dark reddish brown (2.5YR 3/4) when moist; no roots; clear and smooth transition to:

I CR 80-150 +cm rotten rock; frequent hard carbonate concretions, 0-1 Omm, in joints I I I I 134 I I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 4 Observation no. 122/4-4 Mapping unit: HUC Soil classification: eutric Regosol

Laboratory no. / 4945

Horizon Ah

Depth (cm) 0-10/20

pH-H20 (1: 2.5 w/v) 7.4

pH-KCI " 6.9

EC(mmho/cm) " 0.07

C (%) 0.7

CEC(me/100g), pH 8.2 8.0

CEC ( " "), pH 7.0

Exch. Ca (me/1 00g) 3.8

" Mg " 3.0

" K " 0.1

" Na " 0.6

Sum of cations 7.5

Base sat. %, pH 8.2 94

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 77

Silt % (0.05-0.02) 11

Clay % (0.02-Omm) 12

Texture class SL

Fertility aspects 0-20 cm Laboratory no.

General

pH-H2 (1:272 v/v) 6.9 Na/me/100 Mn 0.3 9 (me/100g)

Exch. acidity (me/100g) K " 0.1 P (PPM) 134

C % 0.3 Ca " 8.8 (P-olsen (ppm)

N % 0.07 Mg " 3.4

Remarks:

135 I I f ROFILE DESCRIPTION NO. 5 «Mapping unit HBC BSoil classification calcic Cambisol Agro-climatic zone IV •Observation 122/4-5 •_ocal petrography Gneisses Physiography Hill •Relief macro Undulating ^Relief meso/micro Gullies Vegetation/landuse Shifting cultivation •Overwash/overblow Nil ^General ground water level Deep Erosion Very slight sheet Surface stoniness Fairly stony «Rockoutcrops Nil Flooding Nil Slope gradient 7% [Surface sealing Nil Effective soil depth Deep Internal drainage class Well drained

Profile descriptions

A 0-15/30cm very dark brown (10YR 2/2) moist; gravelly sandy clay loam weak fine to medium, subangular blocky, frequent very fine pores; few medium, common fine and frequent very fine pores; friable when moist, slightly sticky and slightly plastic when wet; gradual and irregular transition to:

B 15/30-57/65cm dark reddish brown (5YR 3/4) moist; very gravelly clay loam; fine pores gradual and wavy transition to:

Bck 57/65-95cm dark reddish brown (5YR 3/4) moist; gravelly clay loam; weak, very fine, subangular blocky, few medium and frequent very fine pores; (at places slightly gravelly soil, in other places petrocalcic or calcic concretions); friable when moist, slightly sticky and slightly plastic when wet; strong effervescence

136 LABORATORY DATA OF PROFILE DESCRIPTION NO. 5 Observation no. 122/4-5 Mapping unit: HBC Soil classification: calcic Cambisol

Laboratory no. / 569 570 571

Horizon A B BCck

Depth (cm) 0-13 0-15/30 15/30- 57/65- 57/65 90

pH-H20 (1:2.5 w/v) 7.9 7.9 8.1

pH-KCI " 7.0 6.9 6.9

EC(mmho/cm) " 0.11 0.10 0.15

C (%) 0.70 0.49 0.22

CEC(me/100g), pH 8.2 14.3 18.8 15.2

CEC ( " "), pH 7.0

Exch. Ca (me/100g) 12.5 17.3 21.6

" Mg " 2.7 2.9 2.3

" K " 0.02 0.08 0.08

" Na " 0.25 0.30 0.14

Sum of cations 15.47 20.57 24.14

Base sat. %, pH 8.2 100 + 100 + 100 +

" " %, pH 7.0

ESP at pH 8.2 - - -

Texture (limited pretreatment)

Gravel % (>2.0mm) - - -

Sand % (2.0-0.05 mm) - - -

Silt % (0.05-0.02) - - -

Clay % (0.02-Omm) - - -

Texture class - - -

137 I

IPROFIL E DESCRIPTION NO. 6 sa» Bvuappin g unit >"< %X?r?-(bE Soil classification humic Acrisols / •Agro-climatic zone 1 ^Observation 122/1-48 Parent material Nepheline phonolite •Physiography Hill •Relief macro Hilly, 25% Vegetation/landuse Wooded bushland/permanent cultivatio of tea Erosion Nil Slope gradient 14%, lower Drainage class Well drained

Profile description

Ap 0-12cm dark reddish brown (5YR 3/2) moist; clay; moderate, fine to medium, subangular blocky; friable when moist, sticky and plastic when wet; many, fine to medium and common coarse pores; many, very fine to fine and very few medium roots; clear and smooth transition to:

AB 12-32cm dark reddish brown (5YR 4/4) moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, very fine to fine and common, medium pores; many, very fine to fine and very few medium roots; gradual and smooth transition to:

Bt1 32-72cm dark reddish brown (5YR 4/4) moist; clay; strong, fine angular blocky and strong medium subangular blocky; friable when moist, many, very fine to fine and common, medium pores; common, very fine to fine roots; gradual and smooth transition to:

Bt2 72-105cm dark red (5YR 4/6) moist; clay; strong medium subangular blocky; friable when moist, sticky and plastic when wet; common very fine to fine and few medium pores; common very fine to fine roots; clear and smooth transition to:

Bt2/C 105-150cm like Bt2 but loam, with rock fragments

138 LABORATORY DATA OF PROFILE DESCRIPTION NO. 6 Observation no. 122/1-48 Mapping unit: HIP Soil classification: humic Acrisol

Field Ref: 122/1- 48

Horizon A Bt, Bt2 Bt3 BC

Depth in cm 0-17 17-32 32-72 72-105 105- 150

Lab. N0./86 7807 7808 7809 7810 7811

Gravel %

Sand % 26 22 20 20 50

Silt % 32 28 20 22 30

Clay % 42 50 60 58 20

Texture class C C C C L

pH-H20 (1:2.5 w/v) 5.5 5.6 5.7 5.6 5.5

pH-Kcl " 4.6 4.3 4.2 4.1 4.2

EC (mmhos/cm) " 0.07 0.05 0.03 0.02 0.03

C % 2.86 1.96 1.22 1.14 0.61

Cat. Exch. Cap. 29.7 28.7 24.7 24.0 11.3 (me/100g)

Exchangeable Cations

Ca (me/100g) 4.1 3.2 2.1 1.9 2.8

Mg " 1.46 0.26 0.26 0.26 0.26

K " 4.80 3.81 1.91 1.91 2.91

Na " 0.27 0.27 0.17 0.17 0.31

Sum " 10.63 7.54 4.44 4.24 4.28

Base Sat. 36 26 18 18 38

Qualitative CaC03 - + - - +

139 PROFILE DESCRIPTION NQ.7

lapping unit EU-PC Soil classification ando-cumulic Nitisols •Agro-climatic zone 1 (Observation 122/1-54 Parent material Lahar complex (Kenyite and volcanic ash) Physiography High level footridges IRelief macro Hilly Vegetation/landuse Forest/wildlife and timber Erosion Nil ISlope gradient 24% Drainage class Well drained

•Profile description

lAh 0-17cm dark brown (7.5YR 3/4) moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, very fine to fine and common, medium pores; abundant, very fine, common fine, few medium and few, coarse roots; clear and smooth transition to:

Bt1 17-45cm dark reddish brown (5YR 3/4) moist; clay; weak, medium, angular blocky and strong, medium subangular blocky; friable when moist, sticky and plastic when wet; common, very fine to fine, few, medium pores; thin patchy clay cutans; few, very fine to fine and common, medium roots; gradual and smooth transition to:

|Bt2 45-112cm dark reddish brown (5YR 3/4) moist; clay; weak, medium angular blocky and strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; thin, broken to patchy clay cutans; few, very fine to medium, pores; gradual and smooth transition to:

|Bt3 112-180 +cm same as Bt2 except strong, medium, subangular blocky structure

140 LABORATORY DATA OF PROFILE DESCRIPTION NO. 7 Observation no. 122/1-54 Mapping unit: R1PC Soil classification: ando cumulic Nitisol

Laboratory no. /86 7835 7836 7837 7838

Horizon Ah Bt1 Bt2 Bt3

Depth (cm) 0-17 17-45 45-112 112- 160

pH-H20 (1:2.5 w/v) 4.2 4.4 4.5 4.7

pH-KCL " 3.9 3.9 4.0 4.0

EC(mmho/cm) " 0.18 0.05 0.05 0.03

CaC03(%) C <%) 3.92 2.11 1.49 1.14

N (%)

CEC(me/100g), pH 8.2 29.0 27.0 26.2 25.7

Exch. Ca (me/100g) 1.7 1.4 1.2 0.8

" Mg " 0.38 0.26 0.22 0.24

" K " 0.91 0.69 0.53 0.39

" Na " 0.27 0.22 0.17 0.12

Sum of cations 3.26 2.57 2.12 1.55

Base sat. % at pH 8.2 11.2 9.5 8.1 6

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (> 2.0mm)

Sand % (2.0-0.05 mm) 32 18 20 22

Silt % (0.05-0.02) 25 13 11 11

Clay % (0.02-0mm) 43 69 69 67

Texture class C C C C

Remarks : * not corrected for organic matter ~ estimated in the field

141 PROFILE DESCRIPTION NO. 8

Mapping unit .RWP ®,?LK2 Soil classification humic Andosols, sodic phase Agro-climatic zone 1 Observation 122/1-60 Parent material Various volcanic rocks Physiography Mt. Kenya forest footridges Relief macro Undulating Vegetation/landuse Forest/wildlife and timber Erosion Nil Slope gradient 5% Soil fauna Termite channels and krotovinas Drainage class Well drained

Profile description

Ah 0-19cm dark yellowish brown (10YR 3/4) moist; loam; weak, medium, crumby; friable when moist, non sticky and non plastic when wet, also thixotropic; many, very fine to fine, few, medium pores; many, very fine to fine, common medium roots; abrupt and smooth transition to:

Ah/B 19-31 cm very dark greyish brown (10YR 3/2) moist; sandy loam; weak, fine to medium, crumby; friable when moist, slightly sticky and slightly plastic when-wet ,alsp thixotropic common, very fine to fine, few, medium pores; many, very fine to fine and common, medium roots; clear and smooth transition to:

Bw1 31-70cm dark brown (7.5YR 3/4) moist; loam; strong, moderate, crumby and weak, fine, subangular blocky, friable when moist, non sticky and non plastic when wet; also, thixotropic, many, very fine to fine few, medium pores; many very fine to fine roots; clear and smooth transition to:

Bw2 70-104cm dark yellowish brown (10YR 3/4) moist; sandy loam; weak, fine, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; also, thixotropic; many, very fine to fine and few, medium pores; many very, fine to fine roots; clear and smooth transition to:

BC 104-173 +cm dark yellowish brown (10YR 4/0) moist; sandy loam; weak to moderately, strong, fine subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; also, thixotropic; common, very fine to fine and few, medium pores; common, very fine to fine roots;

142 LABORATORY DATA OF PROFILE DESCRIPTION NO.8 Observation no. 122/1-60 Mapping unit: R1VP Soil classification: humic Andosols,sodic phase

Laboratory no. /86 7862 7863 7864 7865 7866

Horizon Ah ABh Bw1 Bw2 BC

Depth (cm) 0-19 19-31 31-70 70-104 104- 173 +

pH-H20 (1:2.5 w/v) 5.4 5.4 5.4 5.4 5.5

pH-KCL " 4.4 4.4 4.4 4.4 4.0

EC(mmho/cm) " 0.05 0.05 0.03 0.03 0.03

CaC03 (%)

C (%) 4.78 5.71 4.34 3.61 3.07

N (%)

CEC(me/100g), pH 8.2 25.2 26.6 - - 23.5

Exch. Ca (me/100g) 1.4 2.5 - - 0.5

" Mg " 0.65 1.81 -7 - 0.15

" K " 1.55 1.19 - - 0.30

" Na " 0.22 0.37 - - 0.2

Sum of cations 3.85 3.37 1.27

Base sat.%, 8.2 15 22 23.5

ESP at pH 8.2 9 6.5 — - 15.7

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 48 58 61 59 61

Silt % (0.05-0.02) 38 30 39 31 23

Clay % (0.02-0mm) 14 12 10 10 16

Texture class L SL L SL SL

143 I PROFILE DESCRIPTION NQ.9

Mapping unit R2Pr1 I Soil classification Humic Nitisol Agro-climatic zone I Observation 122/1-55 I Local petrography Kenyanite - Lahars Physiography Foot ridges middle level Relief macro Rolling I Relief meso/micro Terraces Vegetation/landuse Shrubs/farrow Overwash/overblow Nil I General ground water level Very deep Erosion Nil Surface stoniness Nil I Rockoutcrops Nil Flooding Nil Slope gradient 15 I Surface sealing Nil Effective soil depth Very deep I Internal drainage class Well drained Profile descriptions

I 0-19cm dark brown (7.5YR 3/2) moist; clay loam; moderate, medium subangular blocky; very friable when moist, slightly sticky and slightly plastic when wet; many, very fine and fine and common, medium pores; abundant very fine and I fine and few, medium roots; clear and smooth transition to: (lab. no. 7839/86) I A2 19-35cm dark brown (7.5YR 3/4) clay loam; moderate, fine subangular blocky, very friable when moist, slightly sticky and slightly plastic when wet; many, very fine and few, fine pores; abundant, very fine and fine and few medium roots; I gradual and smooth transition to: (lab. no. 7840/86) | A3 35-52cm dark brown (7.5YR 3/4) clay loam to clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, very fine and fine and common, medium pores; abundant, very fine and fine and few, medium roots; clear and smooth transition to: 1 (lab. no. 7841/86) m Bt1 52-140cm red (2.5YR 3/6) moist, clay; strong, moderate subangular blocky; very friable when moist, slightly sticky and slightly plastic when wet; patchy thin clay cutans; many, very fine and few, fine pores; many, very fine and common, fine roots; gradual and smooth transition to: 1 (lab. no. 7842/86) Bt2 140-200cm red (2.5YR 3/6) moist; strong moderate subangular to weak, fine angular blocky; very friable when moist, slightly sticky and slightly plastic when wet; many, very fine and fine, common medium pores; patchy to common clay I cutans; few very fine and fine roots; transition to: I I 144 I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 9 Observation no. 122/1-55 Mapping unit: R2Pr1 Soil classification: humic Nitisol

Laboratory no. /86 7839 7840 7841 7842 7843

Horizon A1 A2 A3 Bt, Bt2 Depth (cm) 0-19 19-35 35-52 52-140 140- 200

pH-H20 (1:2.5 w/v) ( 4.5 4.4 > 4.5 ) 4.4 4.7

pH-KCL " 3.9 3.8 3.8 3.8 3.9

EC(mmho/cm) " 0.04 0.03 0.03 0.03 0.05

CaC03 (%) 1.4

C (%) 4.32 3.51 2.74 1.64 1.11

N (%)

CEC(me/100g), pH 33.6 31.7 27.7 24.6 26.7 8.2

Exch. Ca (me/100g) 0.80 1.0 1.0 0.8 1.1

" Mg " 0.56 0.67 0.80 0.95 0.66

" K " 0.07 0.07 0.11 0.07 0.45

" Na " 0.12 0.27 0.27 0.12 0.27

Sum of cations 1.55 2.01 2.18 1.94 3.48

Base sat. %, pH 8.2 5 6 8 7 9

ESP at pH 8.2

Qualitative CaCO3 - + - - -

Sand % (2.0-0.05 26 18 14 12 10 mm)

Silt % (0.05-0.02) 15 17 11 5 12

Clay % (0.02-0mm) 59 65 75 83 78

Texture class C C C C C

Natural clay 0.25 0.26 0.15 0.06 0.15

145 I PROFILE DESCRIPTION NO. 10

IM apping unit R2Pb Soil classification Umbric Andosol •Agro-climatic zone I (Observation 122/1-46 Local petrography Phonolites and Ashes «Physiography Footridges •Relief macro Undulating \/egetation/landuse Cultivation Overwash/overblow Nil (General ground water level Very deep •Erosion Nil Surface stoniness Nil (Rockoutcrops Nil •Flooding Nil Slope gradient 3-5% •Surface sealing Nil (Effective soil depth Very deep Internal drainage class Well drained

(Profile descriptions

Ap 0-7cm dark brown (10YR 3/3) moist; clay loam; weak, fine subangular blocky; soft when dry, friable to loose when moist, slightly sticky and slightly plastic when wet; abundant, very fine and fine, many, medium pores; many, very fine and fine, few medium roots; clear and smooth transition to:

AB 7-22cm dark brown (10YR 3/3) moist, clay loam; strong, fine to medium subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; abundant, very fine and fine, many, medium pores; many, very fine and fine, few medium roots; clear and smooth transition to:

Bu1 22-45cm dark brown (7.5YR) moist; clay loam to clay; strong, medium subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; abundant, very fine and fine, many, medium pores; many, very fine and fine, few, medium roots; gradual and smooth transition to:

Bu2 45-55cm dark brown (7.5YR) moist; clay, strong, medium subangular blocky and strong fine angular blocky; friable when moist, sticky and slightly plastic when wet; abundant, very fine and fine, many, medium pores; few, very fine and fine roots; gradual and smooth transition to:

Bu3 55-130cm strong brown (7.5YR 4/6) moist; clay; strong, fine subangular and angular blocky; friable when moist, slightly sticky and slightly plastic when wet; abundant, very fine and fine, many, medium pores; few, very fine and fine roots; clear and smooth transition to:

130-200cm (10YR 6/8) moist; gravelly clay loam; strong, fine subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; common, very fine and fine pores; transition to:

146 LABORATORY DATA OF PROFILE DESCRIPTION NO. 10 Observation no. 122/1-46 Mapping unit: R2Pb Soil classification: umbric Andosol

Field Ref: 122/1-46

Laboratory no. /86 7796 7797 7798 7799 7800 7801

Horizon A AB Bu, Bu2 Bu3 BC

Depth (cm) 0-7 7-22 22-45 45-85 85-130 1 30-200

pH-H20 (1:2.5 w/v) 5.2 5.2 5.1 5.1 5.1 5.5

pH-KCL " 4.2 4.2 4.3 4.4 4.5 4.6

EC(mmho/cm) " 0.06 0.06 0.05 0.05 0.04 0.02

C (%) 4.58 3.74 2.29 1.73 0.72 0.34

N (%)

CEC(me/100g), pH 18.7 17.5 16.0 18.0 16.5 12.7 8.2

Exch. Ca (me/100g) 2.10 3.2 1.20 1.6 4.30 1.00

" Mg " 0.66 0.66 0.26 0.26 0.26 0.26

" K " 0.89 0.86 0.77 1.05 0.41 0.05

" Na " 0.22 0.27 0.27 0.35 0.37 0.12

Sum of cations 3.87 5.00 2.50 3.06 5.34 1.43

Base sat. %, pH 8.2 21 29 16 18 32 11

ESP at pH 8.2

Qualitative CaC03 - - - - - •-

Sand % (2.0-0.05 48 50 34 38 32 38 mm)

Silt % (0.05-0.02) 43 40 48 40 40 58

Clay % (0.02-0mm) 10 10 18 22 28 4

Texture class L L L L CL SiL

Natural clay 4.3 4.0 2.7 1.8 1.4 14.5

147 I IPROFIL E DESCRIPTION NO.11

IMappin g unit R2Pbp Soil classification Humic Andosol Agro-climatic zone I IObservation 122/1-47 Local petrography Phonolites and Ashes Physiography Footridges IRelief macro Undulating Relief meso/micro Nil •Vegetation/landuse Cultivation •Overwash/overblow Nil General ground water level Very deep Erosion Nil • Surface stoniness Nil Rockoutcrops Nil •Flooding Nil 'Slope gradient 3-5% Surface sealing Nil •Effective soil depth Very deep •internal drainage class Well drained IProfil e descriptions ,Ap 0-23cm very dark greyish brown (10YR 3/3) moist; clay loam; weak, fine, subangular blocky; friable when moist slightly sticky and slightly plastic when wet; I abundant/very fine and fine, many medium pores; abundant, very fine and fine, medium roots; clear and smooth transition to:

IA B 23-44cm brown to dark brown (7.5YR 4/4) moist; clay loam to clay; strong, medium, à subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, very fine and fine, common, medium pores; many, very fine and I fine, few medium roots; gradual and smooth transition to:

Bu1 44-124cm dark brown (7.5YR 3/4) moist; clay loam to clay; strong, fine, subangular and I strong medium angular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, very fine and fine, common medium pores; many, very I fine and fine, few medium roots; gradual and smooth transition to: 124-170cm dark yellowish brown (10YR 3/4) moist; clay; strong, fine, subangular and E strong medium angular blocky; friable when moist, slightly sticky and slightly I plastic when wet; many, very fine and fine, common, medium pores; few, very fine and fine roots; clear and smooth transition to: I 170-200cm brownish yellow (10YR 6/8) moist; clay loam; weak, fine, subangular blocky; c friable when moist, slightly sticky and slightly plastic when wet; many, very I fine and fine, common, medium pores;

I 148 I I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 11 Observation no. 122/1-47 Mapping unit: R2PbP Soil classification: humic Andosol

Field Ref: 122/1-47

Laboratory no. /86 7802 7803 7804 7805 7806

Horizon A AB Bu, Bu2 BC

Depth (cm) 0.23 23-45 45-124 124-170 170- 200

pH-H20 (1:2.5 w/v) 5.5 5.6 5.8 5.9 5.8

pH-KCL " 4.6 4.7 4.7 5.0 5.2

EC(mmho/cm) " 0.05 0.04 0.02 0.02 0.02

CaC03(%)

C (%) 3.71 2.96 2.76 1.18 0.94 N (%)

CEC(me/100g), pH 8.9 13.7 7.0 5.1 10.0 8.2

Exch. Ca (me/100g) 4.3 1.70 0.6 0.8 1.70

" Mg " 0.66 0.26 0.26 0.11 0.15

" K " 0.77 0.91 0.23 0.03 0.07

" Na " 0.22 0.22 0.12 0.12 0.17

Sum of cations 5.95 3.09 1.21 1.06 2.09

Base sat. %, pH 8.2 67 23 17 21 21

Qualitative CaC03 - - - - +

Sand % (2.0-0.05 44 40 46 36 38 mm)

Silt % (0.05-0.02) 52 50 48 62 56

Clay % (0.02-0mm) 4 10 6 2 6

Texture class SiL L/SiL SL SiL SiL

Natural clay 13 5 8 31 9.3

149 PROFILE DESCRIPTION NO. 12

Mapping unit R2Vr Soil classification dystric Nitisol Agro-climatic zone I Observation 122/1-49 Local petrography Tuffs, lahars and phonolites Physiography Footridges Relief macro Rolling Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overflow Nil General ground water level Very deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 18% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile descriptions

0-26cm dark reddish brown (5YR 3/2) moist; clay loam; strong, fine, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro and few macro pores; abundant, very fine, fine and common medium roots; gradual and smooth transition to:

AB 26-42cm dark reddish brown (2.5YR 3/4) moist; clay; strong, medium, subangular blocky; friable to slightly firm when moist, sticky and plastic when wet; common, micro and few, macro pores; many, very fine, fine and common medium roots; gradual and smooth transition to:

Bt1 42-115cm red (2.5YR 4/6) moist; clay; strong, coarse, subangular blocky and strong medium angular blocky; friable to slightly firm when moist, sticky and plastic when wet; few, thin, clay cutans; common, micro and few, macro pores; many very fine and fine roots; gradual and smooth transition to:

Bt2 115-200cm red (2.5YR 4/6) moist; clay; strong, coarse, subangular blocky and strong, medium, angular blocky; friable to slightly firm when moist, sticky and plastic when wet; patchy, thin, clay cutans; common, micro and few, macro pores; many, very fine and fine roots; transition to:

150 LABORATORY DATA OF PROFILE DESCRIPTION NO. 12 Observation no. 122/1-49 Mapping unit: R2Vr Soil classification: dystric Nitisol

Field Ref: 122/1-P49

Laboratory no. /86 7812 7813 7814 7815

Horizon A AB Bt, Bt2

Depth (cm) 0-26 26-42 42-115 115-180

pH-H20 (1:2.5 w/v) 5.2 5.1 5.1 5.0

pH-KCL " 4.1 4.0 4.0 4.0

EC(mmho/cm) " 0.02 0.03 0.02 0.02

CaC03 (%)

C (%) 2.69 1.70 1.65 1.13

N (%)

CEC(me/100g), 26.7 24.5 19.2 23.0 pH8.2

Exch. Ca (me/100g) 2.1 2.1 0.8 1.0

" Mg " 1.06 1.06 0.66 0.66

" K " 1.81 0.65 0.63 0.11

" Na " 0.22 0.28 0.17 0.27

Sum of cations 5.19 4.09 2.26 2.04

Base sat. %, pH 8.2 19 17 11 49

ESP at pH 8.2

Qualitative CaCO3 + + + +

Gravel % (>2.0mm)

Sand % (2.0-0.05 18 16 14 12 mm)

Silt % (0.05-0.02) 15 9 5 5

Clay % (0.02-0mm) 67 75 81 83

Texture class C C C C

Natural clay 0.2 0.12 0.06 0.06

151 I PROFILE DESCRIPTION NO. 13

•Viclappin g unit R3Br Soil classification dystric Nitisol •^gro-climatic zone I Observation 122/1-58 Local petrography Basalts hysiography Footridges Kelief macro Undulating Relief meso/micro Nil egetation/landuse Cultivation Kverwash/overblow Nil General ground water level Very deep •Erosion Nil •Surface stoniness Nil Rockoutcrops Nil looding Nil Klope gradient 3% Surface sealing Nil iffective soil depth Very deep (nternal drainage class Well drained

'rofile descriptions

AP 0-16cm dark brown (7.5YR 3/4) moist; clay loam; strong, medium, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro I and common, macro pores; common, very fine and fine, medium roots; clear and smooth transition to: I B 16-40cm dark reddish brown (5YR 3/3) moist; clay loam; strong, medium, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro and common, macro pores; common, very fine and fine, medium roots; I clear and smooth transition to:

u1 40-87cm yellowish red (5YR 4/6) moist; clay; strong, medium, subangular blocky and I strong medium angular blocky; friable when moist; sticky and plastic when wet; many, micro and few »common macro pores; few, very fine and fine roots; I gradual and smooth transition to: t1 87-150cm dark red (2.5YR 3/6) moist; clay; strong, medium, subangular blocky; friable I when moist; sticky and plastic when wet; common, very fine and fine, few medium pores; patchy, thin, clay cutans; common very fine and fine, medium I roots; gradual and smooth transition to: EBt 2 1 50-200cm dark red (2.5YR 3/6) moist; clay; strong, fine, subangular and strong, medium, angular blocky; common, very fine and fine, few medium pores; patchy, thin, I clay cutans; few, very fine and fine roots; transition to: I I 152 I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 13 Observation no. 122/1-58 Mapping unit: R3Br Soil classification: Dystric Nitisol

Field Ref: 122/1- 58 Laboratory no. /86 7853 7854 7855 7856 7857

Horizon Ap AB Bu, Bt, Bt2

Depth (cm) 0-16 16-40 40-87 87-150 1 50-200

pH-H20 (1:2.5 w/v) 5.1 5.0 4.9 4.8 4.8

pH-KCL " 4.3 4.2 4.2 4.2 4.2

EC(mmho/cm) " 0.09 0.06 0.08 0.09 0.08

CaC03 (%)

C (%) 2.66 1.69 1.73 0.75 0.73 N (%)

CEC(me/100g), pH 28.7 25.0 24.9 23.1 23.0 8.2

Exch. Ca (me/100g) 3.9 2.5 2.8 2.3 2.5

" Mg " 2.28 1.03 1.42 2.22 1.35 „ .. K 1.71 1.45 1.41 1.53 1.71

" Na " 0.52 0.27 0.32 0.42 0.37

Sum of cations 8.41 5.25 5.95 6.47 5.93

Base sat. %, pH 8.2 29 21 24 29 26

ESP at pH 8.2

Sand % (2.0-0.05 30 20 16 14 14 mm)

Silt % (0.05-0.02) 18 14 12 10 10

Clay % (0.02-0mm) 52 66 72 76 76

Texture class C C C C C

Natural clay 0.34 0.2 0.17 0.13 0.13

153 PROFILE DESCRIPTION NO. 14

Mapping unit R3lr Soil classification humic Nitisol Agro-climatic zone I Observation 122/1-53 Local petrography Phonolite Physiography Footridges Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Very deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 5% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile descriptions

Ap 0-16cm dark reddish brown (5YR 3/4) moist; clay; strong, coarse, subangular blocky; slightly hard when dry, friable to slightly firm when moist, sticky and plastic when wet; common micro and macro pores; common very fine and fine roots; clear and smooth transition to:

AB 16-53cm dark red (2.5YR 3/6) moist; clay; strong, medium, angular blocky and strong, coarse, subangular blocky; slightly hard when dry, friable to slightly firm when moist, sticky and plastic when wet; many micro and few macro pores; patchy thin clay cutans; few very fine and fine roots; gradual and smooth transition to:

Bt1 53-120cm red (2.5YR 4/6) moist; clay; strong, medium, angular blocky and strong, coarse, subangular blocky; slightly hard when dry, friable to slightly firm when moist, sticky and plastic when wet; many micro and few macro pores; continous thin clay cutans; few very fine and fine roots; gradual and smooth transition to:

Bt2 120-200 +cm dark red (2.5YR 3/6) moist; clay; strong, medium, angular blocky and strong, coarse, subangular blocky; slightly hard when dry, friable to slightly firm when moist, sticky and plastic when wet; many micro and few macro pores; continous thin clay cutans; few very fine and fine roots; gradual and smooth transition to:

154 LABORATORY DATA OF PROFILE DESCRIPTION NO. 14 Observation no. 122/1-53 Mapping unit: R3lr Soil classification: Humic Nitisol

Field Ref: 122/1-53

Laboratory no. /86 7831 7832 7833 7834

Horizon Ap AB Bt, Bt,

Depth (cm) 0-16 16-53 53-120 1 20-200

pH-H20 (1:2.5 w/v) 4.5 4.3 4.8 5.0

pH-KCL " 3.8 3.8 4.0 4.0

EC(mmho/cm) " 0.07 0.10 0.06 0.03

CaC03 (%)

C (%) 2.01 1.14 0.79 0.64

N (%)

CEC(me/100g), pH 22.0 15.5 14.5 13.2 8.2

Exch. Ca (me/100g) 1.4 0.8 1.3 1.4

" Mg " 0.55 0.30 0.66 0.85

,. K .. 0.37 0.07 0.03 0.07

" Na " 0.13 0.07 0.12 0.12

Sum of cations 2.45 1.24 2.11 2.44

Base sat. %, pH 8.2 11 8 14 18

ESP at pH 8.2

Qualitative CaCO3 + + - -

Gravel % (>2.0mm)

Sand % (2.0-0.05 14 10 8 8 mm)

Silt % (0.05-0.02) 13 9 7 7

Clay % (0.02-0mm) 73 ' 81 85 85

Texture class C C C C

Natural clay 0.18 0.11 0.08 0.08

155 I I PROFILE DESCRIPTION NO. 15 1 Mapping unit R3lp •Soil classification humic Cambisol (Agro-climatic zone 1 Observation 122/1-42 •Local petrography Phonolite (Physiography Footridges Relief macro Rolling •Relief meso/micro Nil (Vegetation/landuse Cultivation Overwash/overblow Nil •General ground water level Very deep (Erosion Nil Surface stoniness Nil •Rockoutcrops Nil (Flooding Nil Slope gradient 10% •Surface sealing Nil BEffective soil depth Moderately deep Internal drainage class Well drained

Profile description

Ap 0-18cm very dark brown (10YR 2/2) moist; clay loam; weak, medium to coarse, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro pores; many, very fine, few fine very few medium roots; gradual and smooth transition to:

AB 18-30cm dark brown (7.5YR 3/2) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; few, very fine, very, few fine roots; gradual and smooth transition to:

B/R 30-80cm dark brown (7.5YR 3/2) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; few, very fine and very few, fine roots; gradual and smooth transition to:

156 LABORATORY DATA OF PROFILE DESCRIPTION NO. 15 Observation no. 122/1-42 Mapping unit: R3lp Soil classification: humic Cambisol

Field Ref: 122/1- 42

Laboratory no. /86 5282 5283 5284

Horizon Ap AB B/R

Depth (cm) 0-18 18-30 30-80

pH-H20 (1:2.5 w/v) 5.8 5.9 6.2

pH-KCL " 5.0 5.0 4.9

EC(mmho/cm) " 0.10 0.08 0.07

CaCOa (%) 0.8 0.64 0.52

C (%) 2.35 1.51 1.94 N (%)

CEC(me/100g), pH 27.5 25.6 26.2 8.2

Exch. Ca (me/100g) 4.70 3.5 3.50

" Mg " 2.05 2.25 2.35

" K " 1.65 1.59 2.00

" Na " 0.14 0.10 0.18

Sum of cations 8.54 7.44 8.03

Base sat. %, pH 8.2 31 29 31

ESP at pH 8.2

Qualitative CaCO3 + + -

Gravel % (>2.0mm)

Sand % (2.0-0.05 34 . 28 24 mm)

Silt % (0.05-0.02) 30 28 26

Clay % (0.02-0mm) 36 44 50

Texture class CL C C

157 I IPROFIL E DESCRIPTION NO. 16 Mapping unit R3Rr1 Soil classification humic Nitosol I Agro-climatic zone I Observation 122/2-56 Local petrography Kenyite; lahars I Physiography Lower footridges Relief macro Undulating Vegetation/landuse Cultivation I Overwash/overblow Nil General ground water level Very deep Erosion Nil I Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 7% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ap 0-17cm dark reddish brown (5YR 3/2) moist; clay loam to clay; strong, coarse, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro and common macro pores; common, very fine and fine and few medium roots; clear and smooth transition to:

17-40cm dark reddish brown (2.5YR 3/4) moist; clay; strong, coarse, subangular blocky; slightly firm when moist, sticky and plastic when wet; common micro and common, macro pores; few, very fine and fine and few, medium roots; gradual and smooth transition to:

Bt1 40-75cm dark red (2.5YR 3/6) moist; clay; strong, medium, angular and subangular blocky; slightly firm when moist; sticky and plastic when wet; common micro and common macro pores; few, very fine and fine and few, medium roots; gradual and smooth transition to:

Bt2 75-125cm red (2.5YR 4/6) moist; clay; strong, medium, angular and subangular blocky; slightly firm when moist; sticky and plastic when wet; common, micro and common, macro pores; continous thick, clay cutans; few, very fine and fine roots; gradual and wavy transition to:

Bt3 125-200 +cm red (2.5YR 4/6) moist; clay; strong, medium, angular and subangulai blocky; slightly firm when moist; sticky and plastic when wet; common, micro and common, macro pores; continous thick clay cutans; few ver\ fine and fine roots; gradual and wavy transition to:

158 LABORATORY DATA OF PROFILE DESCRIPTION NO. 16 Observation no. 122/1-56 Mapping unit: R3pr1 Soil classification: humic Nitisol

Field Ref: 122/1-56

Laboratory no. /86 7844 7845 7846 7847 7848

Horizon Ap AB Bt, Bt2 Bt3

Depth (cm) 0-17 17-40 40-75 75-125 125-200

pH-H20 (1:2.5 w/v) 4.3 4.5 4.7 4.6 4.7

pH-KCL " 3.9 3.9 3.8 4.0 4.1

EC(mmho/cm) " 0.10 0.04 0.05 0.11 0.08

CaC03(%)

C (%) 1.79 1.16 1.21 1.03 0.80

N (%)

CEC(me/100g), pH 18.2 21.5 19.2 15.5 14.7 8.2

Exch. Ca (me/100g) 1.0 2.3 2.1 1.9 1.0

" Mg " 1.00 1.45 1.03 1.01 1.00

" K " 0.03 0.01 0.02 0.01 0.01

" Na " 0.13 0.16 0.20 0.12 0.07 -

Sum of cations 2.16 3.92 3.35 3.04 2.08

Base sat. %, pH 8.2 12 18 17 14 14

ESP at pH 8.2

Qualitative CaCO3 + + + - -

Gravel % (>2.0mm)

Sand % (2.0-0.05 12 10 8 8 8 mm)

Silt % (0.05-0.02) 6 8 4 4 4

Clay % (0.02-0mm) 82 82 88 88 88

Texture class C C C C C

159 PROFILE DESCRIPTION NO. 17

Mapping unit FVP Soil classification Chromic Cambisol Agro-climatic zone IV Observation 122/2-263 Local petrography Gneisses Physiography Footslope Relief macro Rolling Relief meso/micro Nil Vegetation/landuse Grazing/burning Overwash/overblow Nil General ground water level Deep Erosion Slight sheet Surface stoniness Fairly stony Rockoutcrops Fairly rocky Flooding Nil Slope gradient 16% Surface sealing Moderate Effective soil depth Moderately deep Internal drainage class Well drained

Profile description

A 0-1 Ocm dark reddish brown (2.5YR 3/4) moist; clay; loose, gravels; slightly hard when dry; friable when moist, sticky and plastic when wet; many, micro pores; common, fine roots; gradual and smooth transition to:

B1 10-38cm dark red (2.5YR 3/6) moist; gravelly clay; weak, fine, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; common, fine roots; gradual and smooth transition to:

BC 38-60cm dark red (2.5YR 3/6) moist; gravelly clay; weak fine subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; common, fine roots; gradual and smooth transition to:

160 LABORATORY DATA OF PROFILE DESCRIPTION NO. 17 Observation no. 122/2-131 Mapping unit: FVP Soil classification: chromic Cambisol

Field Ref: 122/2-131

Laboratory no. /86 4392 4393 4394

Horizon A Bu, BC

Depth (cm) 0-10 10-38 38-60

pH-H20 (1:2.5 w/v) 6.2 6.3 6.8

pH-KCL " 5.4 5.2 6.0

EC(mmho/cm) " 0.13 0.09 0.30

CaC03 (%)

C (%) 1.17 0.91 0.80

N03

CEC(me/100g), pH 21.6 17.0 18.6 8.2

Exch. Ca (me/100g) 10.1 7.9 13.2

" Mg " 4.08 3.48 1.88

" K " 0.38 0.10 0.06

" Na " 0.12 0.18 0.30

Sum of cations 14.68 11.66 15.44

Base sat. %, pH 8.2 67.96 68.6 77.6

ESP at pH 8.2

Qualitative CaC03 + + +

Gravel % (> 2.0mm)

Sand % (2.0-0.05 52 46 50 mm)

Silt % (0.05-0.02) 16 18 16

Clay % (0.02-0mm) 32 36 34

Texture class SCL SC SCL

161 I I PROFILE DESCRIPTION NO. 18

(/lapping unit LnPr Soil classification humic Acrisol ^gro-climatic zone III observation 122/3-3 Local petrography Phonolite hysiography Plateau Kelief macro Flat Relief meso/micro Nil Ä/egetation/landuse Cultivation p)verwash/overblow Nil General ground water level Deep rosion Slight splash and sheet Kurface stoniness Nil Rockoutcrops Nil looding Nil Klope gradient 2% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

'rofile description

0-1 5cm dark reddish brown (5YR 3/2) moist; clay; weak, fine, subangular blocky and granular loose when dry, slightly sticky and non plastic when wet; many, macro pores and common, bio pores; common fine roots; clear and smooth transition to:

Ah 15-40cm dark reddish brown (5YR 3/2) moist; clay; moderate coarse subangular blocky; loose when dry, slightly sticky and non plastic wehen wet; many macro pores and common bio pores; very few medium roots; gradual and smooth transition to: K t1 40-70cm dusky red (2.5YR 3/2) moist; clay; weak medium subangular blocky loose when dry, slightly sticky and non plastic when wet; few thin clayskins; many macro pores and common bio pores; very few medium roots; gradual and smooth transition to:

Bt2 70-160 +cm dark reddish brown (2.5YR 3/4) moist; clay; moderate medium subangular blocky; very friable when moist, slightly sticky and non plastic when wet; broken few thin clayskins; many macro pores and few bio pores; very few medium roots;

162 LABORATORY DATA OF PROFILE DESCRIPTION NO. 18 Observation no. 122/3-3 Mapping unit: LnPr Soil classification: humic Acrisol

Field Ref: 1 22/3-3

Laboratory no. /86 4930 4931 4932 4933

Horizon Ap AB Bt, Bt2

Depth (cm) 0-15 15-40 40-70 70-160

pH-H20 (1: v/v) 5.7 6.0 6.2 5.7

pH-KCL " 4.9 5.3 5.6 5.3

EC(mmho/cm) " 0.07 0.07 0.06 0.07

CaC03(%)

C (%) 2.08 1.32 0.91 0.52

N03

CEC(me/100g), pH 27.7 24.0 20.0 14.8 8.2

Exch. Ca (me/100g) 3.1 1.7 1.3 Tr.

" Mg " 2.20 2.00 2.32 1.20

" K " 1.16 0.72 0.68 0.65

" Na " 0.10 0.12 0.06 0.06

Sum of cations 6.56 4.54 4.36 1.91

Base sat. %, pH 8.2 23.7 18.9 21.8 12.9

ESP at pH 8.2

Qualitative CaC03 + + + +

Gravel % (>2.0mm)

Sand % (2.0-0.05 16 14 10 6 mm)

Silt % (0.05-0.02) 24 28 18 12

Clay % (0.02-0mm) 60 58 72 82

Texture class C C C C

163 PROFILE DESCRIPTION NO. 19

Mapping unit LnPC Soil classification dystric Cambiso Agro-climatic zone III Observation 122/3-4 Local petrography Phonolite Physiography Plateau Relief macro Flat Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Fairly rocky Flooding Nil Slope gradient 2% Surface sealing Moderate Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ah 0-25cm very dark grey (5YR 3/1 ) moist; clay; moderate, medium, angular blocky; friable when moist, slightly sticky and non plastic when wet; many macro and bio pores; common, medium roots; gradual and smooth transition to:

Bcs 25-50cm dark reddish brown (5YR 3/3) moist; very gravelly sandy clay loam; moderate, medium, angular blocky; friable when moist, slightly sticky and non plastic when wet; very frequent, hard iron concretions, 0-5mm in size, many macro and bio pores; common, medium roots; gradual and smooth transition to:

BCcs 50-60cm reddish brown (5YR 4/3) when moist; common, prominent very dark grey (10YR4/1 ) and few, prominent red (5YR4/6) mottles; very gravelly sandy loam; structureless, firm when moist, non sticky and non plastic when wet; few macro pores; very frequent hard iron and manganese concretions, 5-1 Omm few fine roots; clear and smooth transition to:

Ccs1 60-100cm dark reddish brown (2.5YR 3/4) moist; very gravelly sandy clay; strong, coarse, granules firm when moist, non sticky and non plastic when wet; few macro pores; very frequent hard iron and manganese concretions, 5-1 Omm; few fine roots; gradual and smooth transition to:

Ccs2 100-160cm + reddish brown (5YR 4/3) when moist; many prominent yellow mottles; very gravelly clay; strong very coarse granular structure, manganese concretions; friable when moist, non sticky and non plastic when wet; many macro and bio pores; very frequent soft iron and manganese concretions, 10-20mm; few fine roots;

164 LABORATORY DATA OF PROFILE DESCRIPTION NO. 19 Observation no. 122/3-4 Mapping unit: LnPC Soil classification: dystric Cambisol

Field Ref: 1 22/3-4

Laboratory no. /89

Horizon Ah BCs BCcs Ces, Ccs2

Depth (cm) 0-25 25-50 50-60 60-100 100-160

pH-H20 (1:2.5 w/v) 5.8 5.4 5.3 5.5 5.9

pH-KCL " 5.0 4.8 5.1 4.8 4.6

EC(mmho/cm) " 0.07 0.02 0.02 0.02 0.03

CaC03 <%)

C (%) 1.35 0.73 0.52 0.47 0.52 N (%)

CEC(me/100g), pH 23.2 13.2 7.9 13.7 14.0 8.2

Exch. Ca (me/100g) 2.1 0.8 Tr. Tr. Tr.

" Mg " 2.04 0.48 0.21 0.18 0.76

" K " 1.12 0.28 0.20 0.16 0.16

" Na " 0.05 0.05 0.05 0.06 0.10

Sum of cations 5.30 1.61 0.46 0.40 1.02

Base sat. %, pH 8.2 23 12 6 3 7

ESP at pH 8.2

Gravel % (>2.0mm)

Sand % (2.0-0.05 28 60 76 46 36 mm)

Silt % (0.05-0.02) 18 8 6 10 12

Clay % (0.02-0mm) 54 32 18 44 52

Texture class C SCL SL SC C

165 PROFILE DESCRIPTION NO. 20

Mapping unit LdBr Soil classification humic Nitosol Agro-climatic zone III Observation 122/2-24 Local petrography Basalts Physiography Plateau Relief macro Flat Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 3% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

AP 0-15cm dark reddish brown (5YR 2.5/2) moist; clay; weak, coarse, subangular blocky; very friable when moist, sticky and plastic when wet; many, micro pores; few, fine and very fine, very few fine and very few coarse roots; clear and smooth transition to:

AB 15-26cm dark reddish brown (5YR 2.5/2) moist; clay; weak, coarse, subangular blocky; very friable when moist, sticky and plastic when wet; many micro pores; few fine and very fine, very few fine and very few coarse roots; clear and smooth transition to:

Bt1 26-56cm dark reddish brown (5YR 2.5/2) moist; clay;moderate, coarse, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutan; very few fine and very few coarse roots; distinct and smooth transition to:

Bt2 56-83cm dark reddish brown (5YR 3/3) moist; clay; moderate, coarse, angular blocky; moderate, broken clay cutans; very few fine and very few coarse roots, gradual and smooth transition to:

Bt3 83-119 dark reddish brown (5YR 3/3) moist; clay; moderate, coarse, angular blocky; moderate, broken clay cutans; very few fine and very few coarse roots; clear and smooth transition to:

166 LABORATORY DATA OF PROFILE DESCRIPTION NO. 20 Observation no. 122/2-24 Mapping unit:LdBr Soil classification: humic Nitisol

Laboratory no. / 3284 3285 3286 3287 3288

Horizon Ap AB Bt, Bt2 Bt3 Depth (cm) 0-15 15-26 26-56 56-83 83-119

pH-H20 (1:2.5 w/v) 5.4 5.5 5.7 5.6 5.8

pH-KCL " 4.4 4.5 4.4 4.6 4.9

EC(mmho/cm) " 0.09 0.07 0.06 0.04 0.04

CaC03 (%) 0.41 0.31 0.22 0.16 0.15

C <%) 0.84 0.81 0.66 0.35 0.21

N (%)

CEC(me/100g), pH 8.2 24.6 25.4 23.8 22.8 23.1

Exch. Ca (me/100g) 3.1 2.9 3.1 2.7 2.5

" Mg " 1.7 1.7 2.0 1.8 1.8

" K " 0.98 0.86 0.70 0.58 0.24

" Na " 0.08 0.05 0.08 0.05 0.05

Sum of cations 5.86 5.51 5.88 5.13 4.59

Base sat.%,pH 8.2 24 22 25 23 20

ESP at pH 8.2

Qualitative CaC03)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 18 16 12 14 10

Silt % (0.05-0.02) 24 20 16 12 12

Clay % (0.02-0mm) 58 64 72 74 78

Texture class C C C C C

167 PROFILE DESCRIPTION NO. 21

Mapping unit LdVr Soil classification mollic Nitisol Agro-climatic zone II Observation 122/1-35 Local petrography Basalts Physiography Plateau Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 3% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

AP 0-14 cm dark reddish brown (5YR 3/3) moist; clay; moderate, fine to medium, subangular blocky; friable when moist, sticky and fine and fine roots; gradual and smooth transition to:

AB 14-27cm dark reddish brown (2.5YR 2.5/2) moist; clay; moderate, fine to medium, subangular blocky; friable when moist, sticky and plastic when wet; fine, many, micro pores; thin, broken clay cutans; fine roots; gradual and smooth transition to:

Bt1 27-54cm dark reddish brown (2.5YR 3/4) moist; clay; moderate, fine to medium, subangular blocky; friable when moist, sticky and when wet; many, micro pores; thin, broken clay cutans; fine roots; distinct and smooth transition to:

Bt2 54-91cm dark reddish brown (2.5YR 2.5/2) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and when wet; many, micro pores; thin, broken clay cutans; fine roots; distinct and smooth transition to:

Bt3 91-155 cm dark reddish brown (2.5YR 2.5/2) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and when wet; many, micro pores; thin broken clay cutans; fine roots; distinct and smooth transition to:

168 LABORATORY DATA OF PROFILE DESCRIPTION NO. 21 Observation no. 122/1-35 Mapping unit: LdBr Soil classification: Mollic Nitisol

Field Ref: 122/1-35

Laboratory no. /86 5254 5255 5256 5257 5258

Horizon Ap AB Bt, Bt2 Bt3 Depth (cm) 0-14 14-27 27-54 54-91 91-155

pH-H20 (1:2.5 w/v) 5.5 5.5 5.3 5.7 5.8

pH-KCL " 4.7 4.4 4.7 4.6 4.6

EC(mmho/cm) " 0.04 0.04 0.04 0.04 0.03

CaC03 (%) 0.19 0.18 0.15 0.18 0.12

C <%) 0.95 0.86 0.65 0.46 0.30 N (%)

CEC(me/100g), pH 8.2 21.5 21.0 21.0 19.9 18.0

Exch. Ca (me/100g) 1.90 2.10 2.30 2.3 2.7

" Mg " 0.75 1.15 1.55 1.50 1.45

" K " 0.82 0.79 0.21 0.11 0.13

" Na " 0.14 0.15 0.19 0.11 0.15

Sum of cations 3.62 4.19 4.25 4.02 4.43

Base saturation %, pH 16.9 19.9 20.2 20.2 24.6 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm) 0 0 0 0

Sand % (2.0-0.05 mm) 12 10 10 8 8

Silt % (0.05-0.02) 14 14 12 14 10

Clay % (0.02-0mm) 74 76 78 78 82

Texture class C C C C

169

PROFILE DESCRIPTION NO. 22

Mapping unit U1Br Soil classification Mollic Nitisol Agro-climatic zone I Observation 122/1-28 Local petrography Basalt Physiography Upland Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 8% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile Description

Ap 0-20cm dark reddish brown (5YR 3/3) moist; clay; weak, moderate, subangularblocky; friable when moist, sticky and plastic when wet; many micro pores; few, very fine and very few, fine roots; clear and smooth transition to:

B^ 20-48cm dark reddish brown (5YR 3/4) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutans; few, very fine roots; clear and wavy transition to:

Bt2 48-80cm dark reddish brown (5YR 3/4) moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; continous, thick clay cutans; gradual and smooth transition to:

Bt3 80-108cm yellowish red (5YR 4/6) moist; clay; strong, medium, subangularblocky; friable when moist, sticky and plastic when wet; many micro pores; continous thick clay cutans; gradual and wavy transition to:

Bt4 108-150cm yellowish red (5YR 4/6) moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; continous thick clay cutans; gradual and wavy transition to:

170 LABORATORY DATA OF PROFILE DESCRIPTION NO.22 Observation no. 122/1-28 Mapping unit: UIBr Soil classification: mollic Nitisol

Laboratory no. /86 5221 5222 5223 5224 5225

Horizon Ap Bt, Bt2 Bt3 Bt4 Depth (cm) 0-24 24-48 48-80 80-108 108- 150 +

pH-H20 (1:2.5 w/v) 6.7 5.7 5.9 6.1 6.0

pH-KCL " 5.6 5.3 5.4 5.5 5.6

EC(mmho/cm) " 0.13 0.12 0.11 0.11 0.11

CaC03 (%) 0.55 0.16 0.13 0.13 0.13

C (%) 0.65 0.98 0.78 0.64 0.23

N (%)

CEC(me/100g), pH 8.2 33.3 28.6 26.4 25.8 23.3

Exch. Ca (me/100g) 7.90 4.9 5.5 5.8 5.1

- Mg " 5.65 3.95 3.65 3.35 3.40

" K " 1.37 0.27 0.15 0.15 0.59

" Na " 0.34 0.10 0.13 0.11 0.55

Sum of cations 15.2 9.22 9.43 9.41 9.6

Base sat.%, PH 8.2 45.6 32.2 35.7 36.4 41.2

ESP at pH 8,2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 16 12 12 12 12

Silt % (0.05-0.02) 16 12 10 10 10

Clay % (0.02-0mm) 68 76 78 78 78

Texture class C C C C C

171 PROFILE DESCRIPTION NO. 23

Mapping unit U1lr Soil classification : mollic Nitosol Agro-climatic zone : I Observation 122/1-34 Local petrography Intermediate rocks Physiography Upland Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 5% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ap 0-15cm dark brown (7.5YR 3/2) moist; clay; porous massive; friable when moist, sticky and plastic when wet; many micro and macro pores; many very fine, fine and medium roots; gradual and smooth transition to:

Bt1 15-33cm dark reddish brown (5YR 3/4) moist; clay; porous massive breaking to weak, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro and macro pores; many, very fine and fine and common, medium roots; clear and smooth transition to:

Bt2 33-44 cm dark reddish brown (5YR 3/4) moist; clay weak, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro and macro pores; many, very fine and fine and common, medium roots; clear and smooth transition to:

Bt3 44-95cm dark reddish brown (5YR 3/4) moist; clay; weak, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro and macro pores; patchy thin clay cutans; very few very fine and fine roots; gradual and smooth transition to:

Bt4 95-1 50 +cm dark reddish brown (5YR 3/4) moist; clay; weak, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro and macro pores; patchy, thin clay cutans; very, few very fine and fine roots; gradual and smooth transition to:

172 LABORATORY DATA OF PROFILE DESCRIPTION NO. 23 Observation no. 122/1-34 Mapping unit: U1lr Soil classification: mollic Nitisol

Laboratory no. /86 5249 5250 5251 5252 5253

Horizon Ap Bt, Bt, Bt2 Bt3 Depth (cm) 0-15 15-33 33-44 44-95 95-150

pH-H20 (1:2.5 w/v) 5.6 5.7 5.9 5.9 5.6

pH-KCL " 4.6 4.6 4.7 4.8 4.5

EC(mmho/cm) " 0.40 0.04 0.03 0.02 0.02

CaC03(%)

C (%) 1.05 0.88 0.76 0.55 0.30

N (%)

CEC(me/100g), pH 8.2 23.2 21.6 21.9 19.1 18.6

Exch. Ca (me/100g) 2.9 1.8 1.9 2.7 1.7

" Mg " 1.90 1.00 1.05 1.25 1.15 ., „ K 1.23 0.71 0.67 0.65 0.53

" Na " 0.18 0.14 0.09 0.18 0.14

Sum of cations 6.21 3.65 3.71 4.78 3.52

Base sat. % pH 8.2 27 17 17 25 19

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 18 20 16 14 14

Silt % (0.05-0.02) 28 24 16 10 10

Clay % (0.02-0mm) 54 56 68 76 76

Texture class C C C C C

173 PROFILE DESCRIPTION NO. 24

Mapping unit U1PC Soil classification ferric Acrisol Agro-climatic zone II Observation 1 22/4-40 Local petrography Lahars Physiography Uplands Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Fairly stony Rockoutcrops Fairly rocky Flooding Nil Slope gradient 6% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ah 0-20cm dark reddish brown (5YR 3/2) when moist; slightly gravelly silty clay; moderate, fine, subangular blocky structure; thin broken clayskins; friable when moist, slightly sticky and slightly plastic when wet; many medium and fine pores; very frequent fine roots few medium roots, and very few coarse roots; clear and smooth transition to:

AB 20-45cm dark reddish brown (5YR 3/3) when moist; clay strong, fine, angular blocky structure; thin broken clayskins; friable when moist, slightly sticky and slightly plastic when wet; many medium and fine pores; frequent fine roots, few medium roots and very few coarse roots; clear and smooth transition to:

Bt 45-90cm dark red (2.5YR 3/4) when moist; clay; strong, medium, angular blocky structure; thin, broken clayskins; friable when moist; slightly sticky and slightly plastic when wet; many, medium and fine pores; frequent, fine roots, few medium roots, very few coarse roots; clear and smooth transition to:

Bcs 90-130cm dark red (2.5YR 3/4) when moist; very gravelly clay; 80%, hard and angular iron and manganese concretions, size 5mm; weak porous massive very fine angular blocky structure; thin broken clayskins; friable, slightly sticky and slightly plastic; common medium and fine pores; common medium roots; gradual and broken transition to:

BCR 130-160 +cm mostly rotten lahar rock with 10% hard and angular iron and manganese concretions, size (average) 5mm

174 LABORATORY DATA OF PROFILE DESCRIPTION NO.24 Observation no. 122/4-40 Mapping unit: U1PC Soil classification: ferric Acrisol

Laboratory no. /86 1129 1130 1131 1132

Horizon Ah AB Bt Bcs

Depth (cm) 0-20 20-45 45-90 90-130

pH-H20 (1:2.5 w/v) 6.1 5.6 5.8 5.8 pH-KCL " 5.1 4.8 5.2 4.9

EC(mmho/cm) " 0.08 0.04 0.05 0.03

CaC03 (%)

C (%) 1.3 ( 1.0 0.9 0.5

N (%)

CEC(me/100g), pH 8.2 31.5 29.7 18.6 23.8

Exch. Ca (me/100g) 7.3 4.3 3.5 3.3

" Mg " 6.7 4.0 3.5 3.3

" K " 1.4 1.0 1.0 0.9

" Na " 0.9 0.7 0.5 0.7

Sum of cations 16.3 10 8.5 8.2

ESP at pH 51.7 33.6 45.7 33.5

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 24 16 42 14

Silt % (0.05-0.02) 16 12 10 12

Clay % (0.02-0mm) 60 72 48 74

Texture class C C C C

175 PROFILE DESCRIPTION NO. 25

Mapping unit U1Vr Soil classification mollic Nitisol Agro-climatic zone I Observation 122/1-30 Local petrography Various volcanic Physiography Uplands Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 8% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile descriptions

Ap 0-24cm dark reddish brown (5YR 3/3) moist; clay; weak, moderate, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; common very few, few fine roots; clear and smooth transition to:

Bt1 24-60cm dark reddish brown (5YR 3/4) moist; clay; moderate, medium ,angular blocky; friable when moist, sticky and plastic when wet; many micro pores; broken thin clay cutans; few very fine, very few fine roots; distinct and wavy transition to:

Bt2 60-90cm dark reddish brown (5YR 3/4) moist; clay; strong, medium, angular blocky; friable when moist, sticky and plastic when wet; many micro pores; broken thin clay cutans; few very fine, very few fine roots; distinct and wavy transition to:

Bt3 90-120cm dark reddish brown (5YR 3/4) moist; clay; strong, medium, angular blocky; friable when moist, sticky and plastic when wet; many micro pores; broken thin clay cutans; few very fine, very few fine roots; distinct and wavy transition to:

Bt4 120-160cm dark red (2.5YR 3/6) moist; clay; strong, medium, angular blocky; friable when moist, sticky and plastic when wet; many micro pores; broken thin clay cutans; few very fine, very few fine roots; distinct and wavy transition to:

176 LABORATORY DATA OF PROFILE DESCRIPTION NO. 25 Observation no. 122/1-30 Mapping unit: U1Vr Soil classification: mollic Nitisol

Laboratory no. /86 5231 5232 5233 5234 5235

Horizon Ap Bt, Bt2 Bt3 Bt4 Depth (cm) 0-24 24-60 60-90 90-120 120- 160

pH-H20 (1:2.5 w/v) 5.6 5.5 5.6 5.4 5.4

pH-KCL " 5.1 4.9 5.1 5.1 4.9

EC(mmho/cm) 0.06 0.06 0.03 0.04 0.05

CaC03 (%) 0.12 0.1 0.09 0.07 0.07

C (%) 1.01 1.02 0.46 0.38 0.27

N (%)

CEC(me/100g), pH 8.2 25.2 24.6 18.7 15.0 15.5

Exch. Ca (me/100g) 3.1 2.30 2.30 2.40 2.10

" Mg " 1.65 1.25 1.57 1.45 2.05

" K " 0.95 0.81 0.32 0.19 0.15

" Na " 0.15 0.12 0.14 0.15 0.16

Sum of cations 5.85 4.48 4.33 4.19 4.46

Base sat %, pH 8.2 23 18 23 28 29

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 12 12 8 6 8

Silt % (0.05-0.02) 10 8 8 6 6

Clay % (0.02-0mm) 78 80 84 88 86

Texture class C C C C C

177 PROFILE DESCRIPTION NO. 26

Mapping unit UVrP Soil classification : dystric Cambisol Agro-climatic zone II Observation 122/1-37 Local petrography Basalts Physiography Uplands Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Fairly stony Rockoutcrops Fairly rocky Flooding Nil Slope gradient 5% Surface crusting Weak Effective soil depth Deep Internal drainage class Well drained

Profile description

Ap 0-15cm dark reddish brown (5YR 3/3) moist; sandy clay loam; weak, fine, subangular blocky; friable when moist, sticky and plastic when wet; common micro and macro pores; clear and wavy transition to:

Bw1 15-50cm dark reddish brown (5YR 3/4) moist; clay loam; strong, fine, subangular blocky; friable when moist, sticky and plastic when wet; common micro and macro pores; clear and wavy transition to:

Bw2 50-100 +cm dark reddish brown (5YR 4/4) moist; sandy clay; strong, fine, angulai and strong medium subangular blocky; friable when moist, sticky ana plastic when wet; common micro and macro pores; clear and wavy transition to:

178 LABORATORY DATA OF PROFILE DESCRIPTION NO. 26 Observation no. 122/1-37 Mapping unit: UVrp Soil classification: dystric Cambisol

Field Ref: 122/1- 37

Horizon Ap Bw, Bw2

Depth in cm 0-15 15-50 50-110

Lab. N0./86 5265 5266 5267

Gravel %

Sand % 20 20 34

Silt % 12 26 18

Clay % 68 54 48

Texture class C C C

pH-H20 (1:2.5 w/v) 6.4 5.9 6.2

pH-Kcl 1:2% 4.8 4.4 4.3

EC (mmhos/cm) 1:2 Vi 0.07 0.05 0.04

CaC03 % 0.18 0.48 0.33

C % 1.07 0.68 0.57

Cat. Exch. Cap. 23.2 17.4 14.6 (me/100g)

Exchangeable Cations

Ca (me/100g) 3.9 2.4 2.3

Mg " 1.65 1.45 1.40

K " 1.95 1.31 0.63

Na " 0.25 0.19 0.26

Sum of cations 7.75 5.35 4.59

Base Sat % pH 8.2 33 31 31

ESP 1.1 1.1 1.8

Qualitative CaC03 - + +

179 PROFILE DESCRIPTION NO. 27

Mapping unit U1XrP Soil classification chromic Luvisol Agro-climatic zone IV Observation 122/2-6 Local petrography Biotite gneisses Physiography Upland Relief macro Gently undulating Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 3-5% Surface sealing Nil Effective soil depth Moderately deep Internal drainage class Well drained

Profile description

A 0-5cm dark brown (7.5YR 3/4) moist; clay; weak, fine, crumbs; friable when moist, sticky and plastic when wet; many, micro pores; few, very fine, common fine roots; clear and smooth transition to:

AB 5-20cm dark red (2.5YR 3/6) moist; clay; strong, moderate, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, very thin clay cutans; many very fine, few fine roots; clear and smooth transition to:

Bt1 20-62cm red (2.5YR 4/6) moist; clay; strong, fine to medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; few, very fine and fine roots; abrupt and smooth transition to:

Bt2 62-90cm dark red (2.5YR 3/6) moist; clay; strong, fine and moderate, angular and subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; continous, thick clay cutans; few very fine roots; transition to:

180 LABORATORY DATA OF PROFILE DESCRIPTION NO. 27 Observation no. 122/2-6 Mapping unit: UlXrp Soil classification: chromic Luvisol

Laboratory no. /85 10892 10893 10894 10895

Horizon A AB Bt,

Depth (cm) 0-5 5-20 20-62

pH-H20 (1:2.5 w/v) 5.9 5.7 5.7

pH-KCL " 5.4 5.4 5.4

EC(mmho/cm) " 0.04 0.03 0.04

CaC03 (%)

C (%) 1.14 0.64 0.59

N (%)

CEC(me/100g), pH 8.2 22.0 20.0 20.0

Exch. Ca (me/1 OOg) 12.3 9.3 8.7

" Mg " 5.4 5.2 6.2

| " K " 0.3 Tr. Tr.

" Na " 0.3 0.1 0.1

Sum of cations 18.3 14.6 15.0

Base sat (%)pH 8.2 83.0 73.0 75.0

, ESP at pH 8.21

I Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 26 20 22

Silt % (0.05-0.02) 12 12 10

Clay % (0.02-0mm) 62 68 68

Texture class C C C

181 PROFILE DESCRIPTION NO. 28

Mapping unit U2UC Soil classification chromic Luvisol Agro-climatic zone III Observation 122/3-99 Local petrography Gneisses Physiography Upland Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 6% Surface sealing Nil Effective soil depth Shallow Internal drainage class Well drained

Profile description

A 0-20cm dark reddish brown (5YR 4/4) moist; sandy clay; moderate, medium, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; common macro pores; sandy clay; clear and smooth transition to:

B 20-50cm dark red (2.5YR 3/6) moist; very gravelly clay; moderate, medium, subangular, blocky structure; common, micro and macro pores; firm when moist, sticky and slightly plastic when wet; clear and wavy transition to:

CR 50-100cm weathering rock

182 LABORATORY DATA OF PROFILE DESCRIPTION NO. 28 Observation no. 122/4-99 Mapping unit: U2UC Soil classification: chromic Luvisol

Laboratory no. /86 597 598

Horizon A Bu

Depth (cm) 10-20 20-50

pH-H20 (1:2.5 w/v) 5.9 6.1

pH-KCL " 4.9 4.6

EC(mmho/cm) " 0.06 0.05

CaC03 (%)

C (%) 0.13 0.13

N (%)

CEC(me/100g), pH 8.2 7.3 14.6

Exch. Ca (me/100g) 1.9 4.3

" Mg " 2.1 3.1

" K " 0.42 0.20

" Na " 0.05 0.09

Sum of cations 4.47 7.69

Base sat. %, PH 8.2 63 57

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 68 53

Silt % (0.05-0.02) 8 5

Clay % (0.02-0mm) 24 42

Texture class SCL SC

183 PROFILE DESCRIPTION NO. 29

Mapping unit U2Br1 Soil classification mollic Nitosol Agro-climatic zone II Observation 122/2-2 Local petrography Basalts Physiography Uplands Relief macro Gently undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 40% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ap 0-15cm dark reddish brown (5YR 3/3) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; common, fine, medium and coarse roots; gradual and smooth transition to:

AB 15-48cm dark reddish brown (5YR 3/3) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutans; common, fine medium and coarse roots; clear and smooth transition to:

Bt1 48-86cm dark reddish brown (5YR 3/4 moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; broken, moderate clay cutans; common fine roots; clear and smooth transition to:

Bt2 86-132cm dark red (2.5YR 3/6) moist; clay; moderate, medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutans; common very fine roots; gradual and smooth transition to:

Bt3 132-200 +cm red (2.5YR 4/6) moist; clay; strong, fine to medium, subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutans; very few very fine roots; transition to:

184 LABORATORY DATA OF PROFILE DESCRIPTION NO. 29 Observation no. 122/2-2 Mapping unit: U2Brn Soil classification: mo'lic Nitisol

Laboratory no. /85 10876 10877 10878 10879 10

! Horizon Ap AB Bt, Bt2 Bt3

Depth (cm) 0-15 15-48 48-86 86-132 132- 200

pH-H20 (1:2.5 w/v) 5.9 5.4 5.1 5.5 5.2

1 5.3 4.8 4.6 5.1 4.6 pH-KCL " EC(mmho/cm) " 0.08 0.04 0.03 0.07 0.06

1 0.2 0.23 0.19 0.15 0.13 CaC03 (%) | C (%) 1.00 0.62 0.65 0.52 0.20 1 N <%) • CEC(me/100g), pH 8.2 25.0 24.0 27.0 17.0 26.0

; Exch. Ca (me/100g) 13.5 9.1 12.3 7.7 8.1

" Mg " 3.3 3.1 2.8 2.9 2.5

" K " 2.6 1.2 0.9 0.3 0.2

" Na " 0.4 0.4 0.7 0.3 0.2

Sum of cations 19.8 13.71 16.7 11.3 11.0

Base sat. % PH 8.2 79 57 62 66 42

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 16 14 12 10 10

Silt % (0.05-0.02) 14 16 14 12 10

Clay % (0.02-0mm) 70 70 74 78 80

Texture class C C C C C

185 PROFILE DESCRIPTION NO. 30

Mapping unit U2XA Soil classification vertic Luvisol Agro-climatic zone IV Observation 1 22/2-6 Local petrography Basalts Physiography Uplands Relief macro Gently undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 2% Surface sealing Nil Effective soil depth Moderately deep Internal drainage class Poorly drained

Profile description

A1 0-15cm black (10YR 2/1) when moist; clay; strong, medium, angular blocky; common small slickensides, 1-4 cm wide; very friable when moist, slightly sticky and slightly plastic when wet; many macro pores; few very fine roots; gradual and smooth transition to:

Bu1 15-60cm black (10YR 2/1) when moist; clay; strong, coarse, angular blocky; common small slickensides, 1-4cm wide; friable when moist, non sticky and slightly plastic when wet; many macro pores; few very fine roots; gradual and smooth transition to:

Bu2ck 60-75cm very dark greyish brown (10YR 3/2) when moist; clay; strong coarse angular blocky; common small slickensides, 1-4cm wide; friable when moist, non sticky and slightly plastic when wet; many macro pores; few very fine roots; gradual and smooth transition to:

186 LABORATORY DATA OF PROFILE DESCRIPTION NO. 30

Observation no. 122/4-6 Mapping unit: U2XA Soil classification:Vertic Luvisol

Laboratory no. /

Horizon A1 Bu1 Bu2ck

Depth (cm) 0-15 15-60 60-75

pH-H20 (1:2.5 w/v) 5.1 5.1 5.1

pH-KCL " 4.9 4.5 4.7

EC(mmho/cm) " 0.06 0.07 0.06

CaC03 (%)

C (%) 0.29 0.26 0.26

N (%)

CEC(me/100g), pH 8.2 16.1 13.6 11.0

Exch. Ca (me/100g) 2.3 2.5 3.6

" Mg " 3.00 2.60 2.20

" K " 1.21 0.67 0.92

" Na " 0.12 0.22 0.22

Sum of cations 6.63 5.99 6.94

Base sat.% pH 8.2 41.0 44.0 63.0

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 20 20 34

Silt % (0.05-0.02) 11 15 23

Clay % (0.02-0mm) 69 65 43

Texture class C C C

187 PROFILE DESCRIPTION NO. 31

Mapping unit U2XC Soil classification dystric Cambisol Agro-climatic zone IV Observation 122/2-26 Local petrography Gabbro norite Physiography Upland Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Moderate sheet Surface stoniness Stony Rockoutcrops Rocky Flooding Nil Slope gradient 6% Surface sealing Nil Effective soil depth Moderately deep Internal drainage class Well drained

Profile description

0-16cm dark reddish brown (5YR 3/3) moist; clay; weak, coarse, subangular blocky; hard when dry, friable when moist; slightly sticky and slightly plastic when wet; many, micro pores; few, very, fine roots; transition to:

Bu1 16-38cm dark red (2.5YR 3/6) moist; sandy clay; weak, medium to coase subangular blocky; hard when dry, friable when moist, slightly sticky and slightly plastic when wet; many micro pores; very, few very fine roots; transition to:

Bu2 38-66cm yellowish red (5YR 4/6) moist; sandy clay loam; moderate, medium to coarse subangular blocky; hard when dry, friable when moist, slightly sticky and slightly plastic when wet; many, micro pores; very, few very fine roots; transition to:

Bu3 66-98cm yellowish red (5YR 4/6) moist; sandy clay loam; moderate, medium to coarse, subangular blocky; hard when dry, friable when moist, slightly sticky and slightly plastic when wet; many micro pores; very few very fine roots; transition to:

188 LABORATORY DATA OF PROFILE DESCRIPTION NO 31 Observation no. 122/2-26 Mapping unit: U2XC Soil classification: dystric Cambisol

Laboratory no. /86 3293 3294 3295 3296

Horizon A Bu1 Bu2 Bu3

Depth (cm) 0-16 16-38 38-66 66-98

pH-H20 (1:2.5 w/v) 5.6 6.2 6.2 6.5

pH-KCL " 4.9 5.3 5.4 5.1

EC(mmho/cm) " 0.20 0.08 0.08 0.09

CaC03(%)

C (%) 0.58 0.58 0.50 0.26

N (%)

CEC(me/100g), pH 8.2 14.0 17.5 15.6 17.0

Exch. Ca (me/100g) 3.9 4.2 4.9 6.3

" Mg " 2.0 2.5 3.5 4.5

" K " 0.20 0.10 0.10 0.06

" Na " 0.12 0.15 0.16 0.19

Sum of cations 6.22 6.95 8.66 11.05

Base sat. %, pH 8.2 44.4 40 56 65

ESP at pH 8.2

Texture (limited Dretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 50 36 36 46

Silt % (0.05-0.02) 20 24 30 16

Clay % (0.02-0mm) 30 40 34 38

Texture class SCL C/CL CL CL

189 PROFILE DESCRIPTION NO. 32

Mapping unit Soil classification dystric Nitosol -^ / J Agro-climatic zone III Observation 122/2-14 Local petrography Basalts Physiography Upland Relief macro Flat Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 2% Surface sealing Weak Effective soil depth Deep Internal drainage class Well drained

Profile description

Ap 0-21 cm dark reddish brown (5YR 3/4) moist; clay; moderate, fine to medium subangular blocky; friable when moist, sticky and plastic when wet; many, micro pores; abundant, very fine roots; gradual and smooth transition to:

Bt1 21-46cm dark reddish brown (5YR 3/4) moist; clay; strong, medium, subangular blocky; friable when moist, sticky and plastic when wet; many micro pores; patchy, thin clay cutans; many, very fine roots; gradual and smooth transition to:

Bt2 46-100cm dark reddish brown (2.5YR 3/4) moist; clay; strong, medium subangular blocky and strong, medium, angular blocky; friable when moist, sticky and plastic when wet; many, micro pores; patchy, thin clay cutans; common, very fine roots; distinct and smooth transition to:

Bt3 100-1 50 +cm dark reddish brown (5YR 3/4) moist; clay; strong, medium, subangular blocky and strong medium angular blocky; friable when moist, sticky and plastic when wet; many micro pores; patchy, thin clay cutans; common, very fine roots; transition to:

190 LABORATORY DATA OF PROFILE DESCRIPTION NO. 32 Observation no. 122/2-14 Mapping unit: PBrl Soil classification: dystric Nitosol

Laboratory no. /85 10916 10917 10918 10919

Horizon Ap Btl Bt2 Bt3

Depth (cm) 0-13 0-21 21-46 46-112 112-150

pH-H20 (1:2.5 w/v) 5.9 7.8 7.6 7.2

pH-KCL " 5.3 5.5 5.7 5.8

EC(mmho/cm) " 0.03 0.05 0.02 0.02

CaC03 (%)

C (%) 1.46 0.89 0.50 0.48

N (%)

CEC(me/100g), pH 8.2 19.0 16.0 9.0 15.0

Exch. Ca (me/100g) 5.1 3.5 3.5 4.1

" Mg " 3.8 1.4 0.9 0.9

" K " 0.1 Tr. Tr. Tr.

" Na " 0.1 0.1 Tr. 0.2

Sum of cations 9.1 5.0 4.4 5.2

Bast sat %,pH 8.2 48 31 49 35

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 15 9 7 7

Silt % (0.05-0.02) 22 20 14 14

Clay % (0.02-0mm) 63 71 79 79

Texture class C C C C

191 PROFILE DESCRIPTION NO. 33

I Mapping unit PnBr2 Soil classification chromic Acrisols Agro-climatic zone IV I Observation 122/2-5 Local petrography Basalts Physiography Plains I Relief macro Gently undulating Relief meso/micro Nil Vegetation/landuse Farrow/cultivation IOverwash/overblow Nil «General ground water level Deep IErosion Slight sheet Surface stoniness Nil Jtockoutcrops Nil fcooding Nil ^lope gradient 2% ^Surface sealing Weak Affective soil depth Very deep mternal drainage class Well drained

I rofile description

1 0-16cm dark reddish brown (2.5YR 3/4) moist; clay loam; weak, medium subangular blocky and weak, fine, angular blocky; friable when moist, sticky and plastic when wet; many micro pores; common very fine roots; clear and wavy transition to:

Bu1 16-68cm red (2.5YR 4/6) moist; sandy clay loam; weak, medium, subangular blocky and weak, fine, angular blocky; friable when moist, slightly sticky and slightly plastic when wet; many micro pores; patchy thin clay cutans; very few fine and common very fine roots; gradual and wavy transition to:

Bu2 68-120 +cm red (2.5YR 4/6) moist; sandy clay loam; weak, medium, subangular and weak, fine, angular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, micro pores; patchy, thin clay cutans; very few fine, common, very fine roots; gradual and wavy transition to:

192 LABORATORY DATA OF PROFILE DESCRIPTION NO. 33

Observation no. 122/2-5 Mapping unit: PnBr2 Soil classification: chromic Acrisols

Laboratory no. /85 10889 10890 10891

Horizon AI Bu1 Bu2

Depth (cm) 0-16 16-68 68-207

pH-H20 (1:2.5 w/v) 5.5 5.4 5.5

pH-KCL " 4.9 4.9 4.7

EC(mmho/cm) " 0.03 0.02 0.02

CaC03(%) 0.52 0.32 0.28

C (%) 0.59 0.59 0.34

N (%)

CEC(me/100g), pH 8.2 18.0 13.0 14.0

Exch. Ca (me/100g) 6.7 2.7 0.7

" Mg " 1.8 1.2 0.3

" K " 1.7 Tr. Tr.

" Na " 0.6 0.1 Tr.

Sum of cations 10.8 3.99 Tr.

Base sat. % pH 8.2 60 30.8 7

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 30 10 10

Silt % (0.05-0.02) 24 22 20

Clay % (0.02-0mm) 46 68 70

Texture class C C C

193 PROFILE DESCRIPTION NO. 34

Mapping unit PnXr Soil classification chromic Acrisol Agro-climatic zone III Observation 122/2-15 Local petrography Basalts Physiography Upland Relief macro Flat Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Nil Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 2% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ap 0-15cm dark reddish brown (5YR 3/4) moist; clay; strong, moderate, subangular blocky; slightly hard when dry; friable when moist, sticky and plastic when,wet; many, micro and few macro pores; many very fine, many fine and few, medium roots; clear and wavy transition to:

AB 15-45cm dark reddish brown (2.5YR 3/4) moist; moderate, medium, subangular blocky; strong, medium, subangular blocky and very, weak, fine, prismatic; slightly hard when dry, friable when moist, sticky and plastic when wet; many, very fine micro and many, macro pores; many, very fine and fine and few medium roots; clear and smooth transition to:

Bt1 45-85cm dark red (2.5YR 3/6) moist; clay; moderate, medium, subangular blocky; strong, medium subangular blocky and very weak, fine, prismatic; slightly hare when dry, friable when moist, sticky and plastic when wet; many very, fine micro and many, macro pores; many, very fine and few fine roots; clear and smooth transition to:

Bt2 85-180cm dark red (2.5YR 3/6) moist; clay; moderate, medium, subangular blocky anc' strong, medium, subangular blocky and very, weak, fine, prismatic; slightly hard when dry; friable when moist, sticky and plastic when wet; many, very fine, micro and macro pores; patchy thin clay cutans; transition to:

194 LABORATORY DATA OF PROFILE DESCRIPTION NO. 34 Observation no. 122/2-15 Mapping unit: PnXr Soil classification: chromic Acrisol

Laboratory no. /86 3244 3245 3246 3247

Horizon Ap AB Bt1 Bt2

Depth (cm) 0-15 15-45 45-85 85-180

pH-H20 (1:2.5 w/v) 6.0 5.0 5.2 4.8

pH-KCL " 5.3 4.6 4.6 4.1

EC(mmho/cm) " 0.19 0.07 0.09 0.04

CaC03 (%)

C (%) 2.35 0.81 0.65 0.31

N (%)

CEC(me/100g), pH 8.2 22.4 18.1 19.6 15.1

Exch. Ca (me/100g) 4.5 3.8 3.0 1.9

" Mg " 3.1 3.1 2.7 1.5

" K " 0.05 0.09 0.27 0.07

" Na " 0.21 0.16 0.16 0.07

Sum of cations 7.9 7.2 6.1 3.5

Base sat. %,pH 8.2 35 39 31 23

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 33 21 25 23

Silt % (0.05-0.02) 11 9 5 3

Clay % (0.02-0mm) 56 72 70 74

Texture class C C C C

195 PROFILE DESCRIPTION NO. 35

Mapping unit PnXr-PBbP2 Extent ha Soil classification chromic Cambisol Agro-climatic zone IV Observation 122/2-12 Local petrography Basalt Physiography Plain Relief macro Flat Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil General ground water level Deep Erosion Slight sheet Surface stoniness Fairly stony Rockoutcrops Nil Flooding Nil Slope gradient 1% Surface sealing Nil Effective soil depth Moderately deep Internal drainage class Imperfectly drained

Profile description

0-7cm brown (10YR 2/1) moist; clay loam; weak, medium, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many, fine and very fine and few medium pores; many very fine and few fine roots; clear and smooth transition to:

Bw1 7-34cm dark yellowish brown (10YR 3/4) moist; sandy clay loam; weak, medium, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; many very fine, fine and medium pores; common very fine, few, fine and many, medium roots; clear and smooth transition to:

Bw2 34-68cm dark yellowish (10YR 3/4) moist; sandy clay; weak, fine, subangular blocky; friable when moist, slightly sticky and slightly plastic when wet; few micro pores; many very fine and common fine roots; transition to:

196 LABORATORY DATA OF PROFILE DESCRIPTION NO. 35 Observation no. 122/2-12 Mapping unit: PnXr-PBbP2 Soil classification: chromic Cambisol

Laboratory no. /85 10911 10912

Horizon A Bw1

Depth (cm) 0-7 7-34

pH-H20 (1:2.5 w/v) 5.9 5.9

pH-KCL " 5.5 5.5

EC(mmho/cm) " 0.05 0.04

CaC03 (%)

C (%) 1.11 0.93

N (%)

CEC(me/100g), pH 8.2 19.0 20.0

Exch. Ca (me/100g) 8.7 7.9

" Mg " 2.1 1.7

" K n 1.0 0.5

" Na " 0.4 0.3

Sum of cations 12.2 10.4

Base sat. %,pH 8.2 64 52

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 49 45

Silt % (0.05-0.02) 18 18

Clay % (0.02-0mm) 33 37

Texture class SCL SCL

197 I

I PROFILE DESCRIPTION NO. 36

(Mapping unit V1PC Soil classification chromic Acrisol Agro-climatic zone I Observation 122/3-48 ILocal petrography Phonolites/agglomerates Physiography Valley Relief macro Hilly IRelief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil IGeneral ground water level Deep Erosion Nil ISurface stoniness Nil Rockoutcrops Nil Flooding Nil ISlope gradient 52% Surface sealing Nil Effective soil depth Very deep IInternal drainage class Well drained I Profile description ABt 0-20cm dark reddish brown (5YR 3/3) moist; clay; moderate, medium, subangular blocky structure; friable when moist, slightly sticky and slightly plastic when I wet; common, thin claycutans and shiny pedfaces; common medium and fine pores; common, very fine and frequent fine and few medium roots, clear and I broken transition to: 20-80cm reddish brown (5YR 4/4) moist; clay; moderate, very coarse, subangular blocky falling apart to moderate, coarse, subangular blocky structure; friable when I moist, slightly sticky and slightly plastic when wet; common, thin clay cutans and shiny pedfaces; many medium and fine pores; few fine and few medium I roots; I I I I 198 I I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 36 Observation no. 122/3-48 Mapping unit: V1 PC Soil classification: chromic Acrisol

Laboratory no./85 8031 8032

Horizon A Bt

Depth (cm) 0-20 20-80

pH-H20 (1: 2.5w/v) 4.4 4.3

pH-KCL " 3.9 4.0

EC(mmho/cm) " 0.05 0.04

CaC03(%)

C (%) 2.8 n.d

N (%) 0.6 n.d

CEC(me/100g), pH 8.2 16.3 12.5

Exch. Ca (me/100g) •\A 0.7

" Mg " 0.4 0.1

" K " 0.6 0.5

" Na " 0.1 0.1

Sum of cations 2.2 1.4

Base sat. %, pH 8.2 13.5 11.2

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 17 13

Silt % (0.05-0.02) 13 11

Clay % (0.02-0mm) 70 76

Texture class C C

199 PROFILE DESCRIPTION NO. 37

Mapping unit V1XrP Soil classification humic Nitosols Agro-climatic zone II Observation 122/1-39 Local petrography Various alluvian/colluvium Physiography River valley Relief macro Undulating Relief meso/micro Nil Vegetation/landuse Cultivation Overwash/overblow Nil General ground water level Deep Erosion Slight sheet Surface stoniness Nil Rockoutcrops Nil Flooding Nil Slope gradient 3% Surface sealing Nil Effective soil depth Very deep Internal drainage class Well drained

Profile description

Ap 0-15cm dark reddish brown (5YR 3/2) moist; clay; moderate, medium, subangular blocky; friable when moist; sticky and plastic when wet; abundant-micro and common macro pores; common, very fine and fine few medium roots; clear and smooth transition to:

AB 15-45cm dark reddish brown (5YR 3/2) moist; clay; moderate, medium, subangular blocky; friable when moist; sticky and plastic when wet; many micro and common macro pores; few very fine and fine and few medium roots; gradual and smooth transition to:

Bt1 45-75cm dark reddish brown (5YR 3/2) moist; clay; moderate, medium, subangular blocky; friable when moist; sticky and plastic when wet; many micro and common, macro pores; patchy, thin clay cutans; very fine, few and fine, few and medium, few roots; gradual and smooth transition to:

Bt2 75-150 +cm dark reddish brown (5YR 3/3) mois; clay; weak, fine, angular blocky and strong medium subangular blocky; friable when moist; sticky and plastic when wet; many, micro and common, macro pores; patchy, thin clay cutans; few ,very fine and fine and few medium roots; gradual and smooth transition to:

200 LABORATORY DATA OF PROFILE DESCRIPTION NO. 37 Observation no. 122/1-39 Mapping unit: V,Xrp Soil classification: humic Nitisols

Laboratory no. /86 5272 5273 5274 5275

Horizon Ap AB Bt1 Bt2 Depth (cm) 0-15 15-45 45-75 75-150

pH-H20 (1:2.5 w/v) 6.1 6.0 5.8 5.6

pH-KCL " 5.2 5.4 4.7 4.8

EC(mmho/cm) " 0.11 0.08 0.09 0.09

CaC03 (%)

C (%) 1.02 0.92 0.73 0.59

CEC(me/100g), pH 8.2 24.4 23.2 20.4 21.5

Exch. Ca (me/100g) 6.70 4.30 3.30 3.10

" Mg " 3.15 3.05 2.15 2.25

" K " 1.95 1.71 1.15 0.83

" Na " 0.22 0.16 0.09 0.10

Sum of cations 12.02 9.22 6.69 6.28

Base sat.%,pH 8.2 50 40 33 29

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 30 28 24 18

Silt % (0.05-0.02) 24 22 24 18

Clay % (0.02-0mm) 46 50 52 64

Texture class C C C C

201 I

IPROFIL E DESCRIPTION NO. 38 I Mapping unit BXd ISoi l classification pellic Vertisol Agro-climatic zone IV Observation 122/2-10 I Local petrography Various materials Physiography Bottomland Relief macro Gently undulating I Relief meso/micro Nil Vegetation/landuse Grazing Overwash/overblow Nil I General ground water level Shallow Erosion Nil Surface stoniness Nil I Rockoutcrops Nil Flooding Nil Slope gradient 3% I Surface sealing Nil Effective soil depth Deep I Internal drainage class Imperfectly drained Profile description

I Ap 0-17cm very dark greyish brown ( 10YR 3/1 ) moist; clay; weak, fine, subangular blocky; friable when moist; sticky and plastic when wet; many micro and macro pores; I common, very fine and few, medium roots; clear and smooth transition to: Bu1 17-42cm very dark greyish brown (1OYR 3/1 ) moist; clay; weak, fine, subangular blocky; friable when moist; sticky and plastic when wet; common very fine and fine I pores; continous, thick pressure faces; common, fine roots; clear and smooth I transition to: Bu2 42-83cm very dark greyish brown ( 10YR 3/1 ) moist; clay; moderate, fine, angular blocky and moderate, fine, prismatic; continous, thick pressure faces; very few, fine I roots; clear and smooth transition to:

|ßu3 83-100 +cm very dark greyish brown (10YR 4/1) moist; clay; when moist, weak fine subangular blocky; friable when moist; sticky and plastic when wet; common, very fine and fine pores; continous, thick pressure faces; I common, fine roots; clear and smooth transition to: I I 202 I I I LABORATORY DATA OF PROFILE DESCRIPTION NO. 38 Observation no. 122/2-10 Mapping unit: BXd Soil classification: pellic Vertisol

Laboratory no. /85 10904 10905 10906 10907

Horizon Ap Bu1 Bu2 Bu3 Depth (cm) 0-17 17-42 42-83 83-100

pH-H20 (1:2.5 w/v) 7.2 7.8 7.9 7.9

pH-KCL " 6.8 7.0 7.2 7.2

EC(mmho/cm) " 0.13 0.14 0.19 0.19

CaC03 (%) 0.27 0.23 0.2 0.2

C (%) 0.82 0.59 0.84 0.73

N (%)

CEC(me/100g), pH 8.2 47.0 47.0 45.0 45.0

Exch. Ca (me/100g) 30.3 35.1 34.5 37.9

" Mg " 9.5 11.1 18.6 9.5 „ „ K 0.1 Tr. Tr. Tr.

" Na " 0.4 0.7 0.7 0.2

Sum of cations 40.3 46.9 53.8 47.6

Base sat. %,pH 8.2 86 100 100 100

ESP at pH 8.2

Texture (limited pretreatment)

Gravel % (>2.0mm)

Sand % (2.0-0.05 mm) 25 25 27 27

Silt % (0.05-0.02) 16 14 12 12

Clay % (0.02-0mm) 59 61 61 61

Texture class C C C C

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