ADDIS ABABA UNIVERSITY

SCHOOL OF GRADUATE STUDIES

Micronutrient Status of Vertisols and Cambisols in two Agro - ecological

zones of Tigray, Northern Ethiopia.

A Thesis Submitted to

School of Graduate Studies

Addis Ababa University

In Partial Fulfillment for the Degree of Master of Science in Biology

(Botanical Sciences).

Tsegay Berhane

June 2003. Addis Ababa University

School of Gradate Studies

Title of the Thesis: - Micronutrient Status of Vertisols and Cambisols in two

Agro - ecological zones of Tigray, Northern Ethiopia.

By Tsegay Berhane

Department of Biology, Faculty of Science

1l.ddis 1l.baba University

Approved by the Examining Board

Name Signature

Chairman, Department Graduate Committee

Research Advisor

Examiner

Examiner ADDIS ABABA UNIVERSITY

SCHOOL OF GRADUATE STUDIES

Micronutrient Status of Vertisols and Cambisols in two Agro - ecological

zones of Tigray, Northern Ethiopia.

A Thesis Submitted to

School of Graduate Studies

Addis Ababa University

In Partial Fulfillment for the Degree of Master of Science in Biology

(Botanical Sciences).

Tsegay Berhane

June 2003. Acknowledgement

I am very much indebted to my research advisor Dr. Fisseha Itanna for his unreserved and continued guidance and support for the completion of this study. Moreover, I would like to thank him once again for his critical and valuable suggestions from the beginning of the research proposal through fieldwork and write up.

Special appreciation goes to my co- advisor Dr. Mitiku Haile for his professional guidance during the fieldwork of this thesis. Grateful thanks and appreciation goes to Dr.

Fassil Kebede and Dr.Jan Nyssen for their assistance and support during the fieldwork.

I am deeply indebted to technicians of the soils laboratory of the Department of Land

Resource Management and Environmental protection, Mekelle University and National

Soil Laboratory, for soil analyses.

My appreciation also goes to the Biology Department of Addis Ababa University for its financial assistance for the study.

Grateful thanks and appreciation go to my workmates: Girmay G/medhin, Tekle Shifraw,

Werede Gessessie and Hubur Gebrekidane for their encouragement. Heartfelt thanks go to W/ro Genet Mergia for support in writing this thesis.

Finally but not the least I am grateful to my wife Hintsa Haddis, my mother and mother - in-low for their encouragement during the period I was away for field work, course work and write up of this thesis. Without their moral supports and encouragement, I would not have been able to complete this study. Table of Contents Pages

Acknowledgement i

List of Tables v

List of Appendix Tables vi

List of Figures vii

Abstract x

1. Introduction 1

2. Objectives of the Study 6

2.1. General 6

2.2. Specific 6

3. Literature review 7

3.1. Source of micronutrients 7

3.2. Solubility and availability of micronutrients 8

3.3. Micronutrients in soils and plants 9

3.3.1. Iron (Fe) 9

3.3.2. Copper (Cu ) 10

3.3.3. Zinc (Zn) 10

3.3.4. Manganese (Mn) 11

3.4. Micronubient interaction 11

3.5. Factors affecting the availability of micronutrient 12

3.6. Micronutrient soil test 13

3.7. Leaf analysis for micronutrients 14

ii 3.8. Micronutrient status of Ethiopian soils 14

4. Material and Methods 16

4.1. Description of the Study Sites 16

4. 1.1. General 16

4.1.2. Adigudom 16

4.1.3. Dogua Tembien 20

4.2. Preparation and Laboratory analysis of Soil samples. 23

4.2.1. Physical analysis 23

4.2.1.1. Bulk Density 23

4.2.1.2. Texture and Soil moisture 24

4.2.2. Chemical analysis 24

4.2.2.1. % organic matter and organic carbon 24

4.2.2.2. Total Nitrogen 24

4.2.2.3. Available Phosphorous and Carbonate 25

4.2.2.4. Exchangeable cations (Ca, Mg, Na and K) 25

4.2.2.5. Available micronutrients (Fe, Mn ,Zn, and Cu) 26

4.3. Green house pot experiments 26

4.4. Green house pot experiments operation 27

4.5. Plant sample preparation for chemical analyis 27

4.6. Ashing and determination of plant Fe, Mn, Zn and Cu. 28

5. Results 29

5.1. Soil analysis 29

5.2. Foliar analysis 38

iii 6. General discussion 44

6.1. Soil Reaction 44

6.2. Electrical conductivity 44

6.3. Available phosphorus 45

6.4. Total Nitrogen 45

6.5. Soil organic matter 45

6.6. Soil parameters and micronutrient interaction 46

6.6.1. Texture and micronutrients 46

6.6.2. pH and micronutrients 46

6.6.3. Available phosphorus and micronutrients 47

6.6.4. Exchangeable bases, CEC, base saturation and

micronutrients. 47

6.6.5. % OC, % TN and micronutrients. 48

6.7. Causes of Zinc defiCiency at Adigudom and

Dogua Tembien 48

7. Conclusion and Recommendation 50

7.1. Conclusion 50

7.2. Recommendation 51

8. Reference 52

9. Appendix 60

iv List of Tables

Page

Table 1:- DTPA extractable micronutrients distribution of

Dogua Tembien soil Catena. 34

Table 2:- DTPA extractable micronutrient distribution of

Adigudom Soil Catena. 34

Table 3:- Chi- square test statistics comparing Dogua Tembien

and Adigudom. 36

Table 4:- Analysis of Variance between and within soil

types of each region 37

Table 5:- Correlation analysis showing relationship between

plant and soil values. 38

v List of Appendix tables

Page

Table Ai: - Physical and Chemical Soil analysis of Dogua

Tembien (Vertisol). 66

Table A2: - Physical and Chemical soil analysis of

Dogua Tembien (Cambisol). 66

Table A3:- Physical and Chemical soil analysis of

Adigudom (Vertisol). 66

Table A4:- Physical and Chemical soil analysis of

Adigudom (Cambisol). 66

Table A5 (a):- Means 66

Table A5 (b):- Means 67

Table A5 (c ):- Means 67

Table A5 (d) :- Means 67

Table A6: - Kruskal-Wallis Test for soil physical and chemical

property for profIle pits of Dogua Tembien and

Adigudom. 68

Table A7: - Test of Homogeneity of variance of soil Physical and

Chemical property of profile soil. 69

vi Table A8: - Speannan's Rho (Non Parametric) correlation between

Soil Parameters 70

Table A9: - Plant versus surfaces soil micronutrients. 72

Table AIO: - Mean of Plant extractable micronutrient. 72

Table All: - Broad rating of soil parameter. 73

Table A12:- Indicative rating for foliar analysis of

micronutrients in ppm. 74

Table A13:- Result sheet for surface soils analysis

(Oogua Tembien and Adigudom). 75

vii List of Figures

Page

Figure 1:- Yearly rainfall at Adigudom. 18

Figure 2:- Schematic representation of the soil catena at

Adigudom 19

Figure 3:- Yearly rainfall at Hagerse1am. 21

Figure 4:- Schematic representation of the soil catena in kebele

Selam Farmers' Association. 22

Figure 5:- Map of Dogua Tembien and Adigudom district in

Tigray Region. 22

Figure 6:- Dendrogram using average linkage (between soil types) 35

Figure 7(a):- Regression analysis showing relationship between

plant - Fe and soil-Fe values. 39

Figure 7(b):- Regression analysis showing relationship between

plant - Mn and soil-Mn values. 40

Figure 7(c):- Regression analysis showing relationship between

plant Zn and soil- Zn values. 41

Figure 7(d):- Regression analysis showing relationship between

plant - Cu and soil - Cu values. 42

Figure 8: - Dendrogram using average linkage of barely grown on

Vertisol and Cambisol soil. 43

viii List of Acronyms

A.F.R Actual Fertilizer rate

A.S.R Actual Seeding rate

BOPED Bureau of Planning and Economic Development

DTPA Diethylene triamine penta acetic acid.

EARO Ethiopian Agricultural Research Orgaruzation.

EB Ethiopian Birr

FAO Food and Agriculture Orgaruzation

GPPTf Green Promotion Project in Tembien . Tigray.

Ha Hectare

HTS Hunting Technical Service.

ITCZ Inter- Tropical Convergence Zone.

NMSA National Meteorological Service Agency.

NPK Nitrogen. Phosphorous and Potassium.

REST Relief Society of Tigray.

R.F.R Recommended fertilizer rate.

SAERf Sustainable Agricultural and Environmental

Rehabilitation for Tigray.

TFAP Tigray forestry action programme.

TLU Tropical Livestock Unit.

ix List of Symbols

ANOVA Analysis of variance.

Av.P Available Phosphorous.

AAS Atomic absorption spectrophotometer.

Base. Sat% - Percent of base saturation.

Oc Degree centigrade.

CEC Cation exchange capacity.

% Percent

C/N Carbon to nitrogen ratio. ds/m­ Deci siemen per meter.

EC Electrical conductivity. g.cm-3- gram per centimeter cube.

M.C. Moisture Content.

Mm millimeter.

OM Organic matter.

PH Soil reaction.

Ppm Parts per million.

T.N Total nitrogen.

x Abstract

Surface soil samples of Vertisols and Cambisols of 0-20 cm depth and leaf samples of barely at 50%jlowering stage grown on surface soils of Vertisols and

Cambisols were collected from Adigudom and Dogua Tembien soil catenas to study the micronutrient cations (Fe, Mn, Zn and Cu). DTFA at pH 7.3 was used for determination of the micronubients. In the extracts, micronutrients were determined with atomic absorption spectro photometer. The soil analysis revealed that Fe, Mn and Cu were at sufficient range but Zn was deficient. The relatively higher concentrations of Co, Mg, sand fraction, and pH are some of the factors contribUting to Zn deficiency. Moreover, removal of surface soil by erosion and poor land management practices enhance Zn deficiency in both study sites.

The leaf analysis indicated that of the micronutrients (Fe, Mn and Zn), Cu was at deficient level. Soil pH and silt fraction had negative correlation with Cu. On the other hand linear regression analysis indicated that there was 94% dependency of plant Cu on soil Cu.

xi 1. INTRODUCTION

Ethiopia, with great ecological diversity, lies between 5° 45' to 15° N latitude and 31°25' to 4So

35'E longitude, having an altitude ranging from ISO m below sea level to 4620 m above sea level.

The total geographic area of Ethiopia is about 112 million hectare of which 66% is estimated to

be suitable for agliculture (Mintesinot Behailu, 2002).

Tigray belongs to African dlY lands, which is called the Sudano-Sahelian region (Wan'en and

Khogali, 1992). It is charactelized by sparse and uneven distlibution of seasonal rainfall, and

frequent OCCUl1'enCe of drought. The amount of rainfall increases with altitude and from east to

west, and decreases from south to north. Average rainfall varies from about 200 rnm in the

northeast lowlands to over 1000 mm in the southwestem highlands. In the central and

southwestem part of the region, average rainfall approaches 1000 mm. Rainfall declines again

with decreasing altitude as one moves further to the west.

In Tigray, altitude valies from 500 meters above sea level (m.a.s.!.) in the northeast to almost

4000 m.a.s.1. in the south west. In the east of Tigray, there is an escarpment that drops from 2000

m.a.s.1. steeply to 500 m.a.s.1. About 53% of the land is lowland (Kolla ... less than 1500 m.a.s.I.),

39% is medium highland (Weina dega .... 1500 to 2300 m.a.s.l.) and S% is the upper highland

(Dega ... 2300 to 3000 m.a.s.l.) (BOPED, 1995).

1 f. ('

Due to the marked variation in topography and altitude, there are different agro-ecological niches

or microclimates within short distances (Amare Belay, 1996). Tigray has 13 major soil types:

Cambisols, Rendzinas, Lithosols, Acrisols, Fluvisols, Luvisols, Regosols, Nitasols, Arenosols ,

Vertisols, Xerosols, Solonchacks, and Andosols (TFAP, 1996). Cambisols are the most

extensive arable soils in Tigray. Vertisols are developed in the higher rainfall areas of the south

on alluvium delived from basalt. In the eastem part of the Region, the soils are mostly developed

under arid condition where the weatheJing process is slow and as a result, very shallow Lithosols

are dominant on the steep slopes. In the westem part of the region, the soil type varies

according to the parent material (REST, 1996). In the Tembien region Cambisols, Vertisols and

Luvisols occur most commonly (TFAP, 1996). Cambisols are described as light, yellow or

white, not compact, freely draining with vatiable texture and depth, Vertisols are black in colour,

heavy with drainage problems during peJiods of high rainfall, relatively compact, less fertile and

with good water holding capacity. Luvisols are red, relatively fertile, fliable and well drained

(GPPTT,1996).

In Tigray, soil nutrient depletion is a cJitical problem for agricultural production (Fitsum Hagos

et aI., 1999). Soil nutrient depletion estimates are not available in Tigray. For Ethiopia as a

whole, estimated nutrient losses were more than 80 kg of nutrients per hectare in 1993 (including

41kg of N, I3kg of P2 Os and 31kg of K2 0), among the highest rates of depletion in Sub-Saharan

Africa (Stoorvogel and Smaling, 1990). Sutcliffe (1993) estimated the impact of nutJient

depletion due to buming of dung and crop residues in the Ethiopian highlands to be 465,000 tons

of grain and 1 million tropical livestock units (TLU) of livestock production in 1990 valued at EB

580 million.

2 Soil erosion and nutrient depletion are exacerbated by the problem of moisture stress inherent in the semi-aJid environment of Tigray (Fitsum Hagos et.al, 1999). The amount of rainfall is not sufficient to sustain nOlIDal crop growth in most Palts of Tigray unless water-harvesting mechanism is introduced. The problem is of course much worse in poor rainfall areas, and where soils are thin and degraded. The velY thin layer of topsoil and low organic matter content of the soil in many places as a result of erosion and limited recycling of organic matter limit the moisture. The moisture in tum reduces the ability of plants to utilize the nutrients that are available, leading to increased nutrient losses through leaching and volatilization.

In Ethiopia, there are mosaic of soil types, which vmy in their characteJistics and having diverse crop productivity (Getachew Sime, 2002). According to Fisseha Itanna (1992), in the highlands of Ethiopia, Vertisols fOlID association with Cambisols and Andosols. Fikru Abate (1985) rep0l1ed that Vertisols are associated with EutJic Nitosols, Eutric and Chromic Cambisols,

Lithosols, Andosols and Chromic Luvisols to a low extent. Fassil Kebede (2002) rep0l1ed an association of Leptosols, Cambisols intercepted with Leptosols, Vel1isols (Vertic) Luvisols and

Vertisols in the highlands of Tigray. Moreover, Nyssen (1996) rep0l1ed an association of

Leptosol, Regosal, Cambisol and Vertisol along soil catena in the highlands of Tigray.

According to Fisseha Itanna (1992), systematic study of micronutJients based on catenaIY distribution at different agro- ecological zones revealed better micronutrient status of some

Vertisol associations in Ethiopia. Moreover, Fisseha Itanna (1992) rep0l1ed that the association of Vertisols with other soils in the geomorphic units can supply comprehensive knowledge of their pedogenesis and nutrients status. Another rep0l1 by Hall (1983) indicated that geomorphology plays a major role in the landscape. According to Getachew Sime (2002), soil

3 properties such as organic matter, bulk density, texture, and pH follow systematic patterns of distribution on the landscape.

Fisseha Itanna (1992) also revealed that topography plays a great role in nutdent disttibution along a catena. The Vertisols occupying the lowest positions in the landscapes serve as a major reservoir for almost all micronutrients, having higher nuttient reserves than their associates.

Belay Tegene (1992) described that differences in topography cause soil fotmation in definite pattem, whenever the parent material and the climate do not change over the area.

According to Getachew Sime (2002), plant analyses at certain stages of growth can be used to indicate whether there is deficiency, sufficiency or an excess absorption. Micronutrient concentrations in plant tissue usually reflect the factions of the respective elements available in soils (Sillanppa, 1982). There has been much interest in plant analyses as possible means of finding out what micronutrients a soil type cannot supply adequately to the plant grown on it.

Desta Beyene (1983) dUling his first attempt of diagnosing the micronuttient status of Ethiopian soils showed that the status of (Fe) and manganese (Mn) were usually at an adequate level while zinc (Zn) contents were vety vatiable ranging between relatively low to high. Copper (Cu) is the one most likely deficient. Response to Zn, however, can be expected at several areas of Ethiopia.

Fisseha Itanna (1992) revealed that Zn contents of most Vertisols in central Ethiopia are found to be deficient. Similat'ly, Getachew Sime (2002) showed that Zn was deficient micronutrient in

Vettisol and Cu in Cambisol.

Although micronutrients are equally important as macronuttient for plant growth, vety little attention has been given so far for studies related to micronutrients in Ethiopia. The soils of the

4 study area: Adigudom and Dogu'a Tembien in Tigray Region, are highly degraded and with low fertility. The roles of micronutrients in the improvement of crop yields are known to be crucial. Therefore, it would be wise to make comprehensive study of the available soil and plant micronutrients in the study area for any conceivable ameliorative measures to be taken in the future.

There is also hardly any well documented soil micronutrient studies relating Vertisols and

Cambisols associations in Tigray. It was, therefore, in light of these gaps that, this research project was proposed.

5 2. Objectives of the Study

2.1. General

The general objective of the research study is to assess the micronutrient potential of Vertisol and

Cambisol associations in Adigudom and Dogu'a Tembien, which will contribute to the database required for sustainable development and management of the soils in Adigudom and Dogu'a

Tembien and other parts of the Region,

2.2. The specific objectives are to:

• study and compare the micronutrient status of Adigudom and Dogu'a Tembien soils

with a established benchmark soil nutrient;

• detelmine, how topographic position affects the micronutrient status of the soils;

• find out if the micronuttient levels of Vertisols and Cambisols are sufficient, in

excess, or deficient levels in both areas;

• undertake leaf analysis of barely crop grown in the greenhouse, con'elate the result

with the soil test data;

• come out with some alternatives that could rectify the micronutrient status of the soils

in Adigudom and Dogu'a Tembien

6 3. Literature Review

3.1. Sources of Micronutrients

According to Brady and Weil (2002), deficiencies and toxicities of micronutrients are related to the total contents of these elements in the soil. Sources of micronutrients vary markedly from area to area. Moreover, micronutrient sources vary considerably in their physical state, chemical reactivity and availability to plants. In general, micronutrient sources are classified as: inorganic, synthetic chelates and natural organic complexes.

Inorganic sources consist of oxides, carbonates and metallic salts such as sulfates, chlotides and nitrates. Sulfates of Cu, Mn and Zn are the most common metallic salts used because of their high water solubility and plant availability (Brady and Weil, 2002).

Synthetic chelates are another source of micronuttients, which are fOimed by combining a chelating agent with metal through co-ordinate bond. Stability of the metal- chelate bond affects availability of the micronutlient metals to plants (Brady and Weil, 2002). Stability of the metal­ chelate affects availability of micronutrients to plants. The major sources of trace elements are many; namely: for Fe (oxides, carbonate and silicates), Zn (sulfides, carbonate and silicates) and

Cu (sulfides, hydroxyl, carbonate and oxides) (Brady and Weil, 2002).

Organic matter is an impottant secondary source of some of the micronutrients. Several micronuttients are found as complex combinations in humus (Brady and Weil, 2002). For example, organic matter often tightly holds copper and its availability to plants will be velY low.

Profiles of uncultivated soil tend to have higher concentrations of micronutrients in the sUlface soil, much of them are in the organic matter (Brady and Wei!, 2002). The elements present in the

7 organic matter are not always available to plants but the decomposition of organic matter is undoubtedly an important fertility factor. A good example of organic matter is animal manure, which is a good source of micronutrients.

3.2. Solubility and availability of micronutrients

The solubility of micronutrients in soils has importance in their bio-availability (Getachew Sime,

2002). According to Rose (1994) the solubility and bioavailability of heavy metal ions is variable because many factors affect their concentrations in the soil solution. Brady and Weil

(2002) revealed that intensive cropping removed plant nutrients in the harvested crop. According to SiUanpaa (1982), the amount of trace elements removed yearly with normal crop yields represents (Mn500, Zn250 and Cu 50 grams (1m)). This represents only a very small proportion, which is less than one percent of the total amounts of micronutJients present in soils.

The total amounts of micronutrients in soil naturally have an essential influence on the soluble or plant available amounts. SiUanpaa (1982) reported the total content of a micronutrient might have essential influence on its soluble or plant available contents. Availability can be influenced by other factors such as pH, organic matter, texture, clay mineral content, redox-potential, temperature and other elements, etc. Thus, total content is seldom a reliable index of the available micronutrient status of soils. Similarly, Fisseha Itanna (1992) also reported that the solubility and availability of DTPA (diethylene triamine penta actic acid) extractable micronutrients is largely influenced by clay content, pH, carbonate, organic matter, CEC and phosphorous levels in the soil among other factors.

Trace elements are found in soil in different forms; namely, in soil solution, exchangeable fOlms, organic matter bound, precipitated, in soil minerals, etc (Sillanpaa, 1982).

8 3.3. Micronutrients in Soils and In Plants

Micronutrient concentrations in plant tissue usually reflect the fraction of the respective elements available in soils (Sillanpaa, 1982). The amounts of micronutrients removed yearly with normal crop yields vary greatly depending on the crop, yield level, soils and factors affecting uptake and availability. It is obvious that even in the most selious cases of deficiency the total amounts far exceed the requirements of crops (Sillanpaa, 1982). Micronutlients can be toxic if taken in large amounts. At low levels of a nutlient, deficiency and reduced plant growth may occur.

3.3.1. Iron (Fe)

Iron complises about 5% of the earth's cmst and is the fourth most abundant element in the lithosphere (Katyal and Randhawa, 1983). The total Iron (Fe) contents in most soils are quite high ranging from 1,000 to 50,000 mg kg'l(Havlin et.al,1999). Fenuginous soils contain a higher percentage of iron (>lO percent). Sandy soils contain low amounts of total iron (around 1 %) and leached acid sands the least (<1 %) (Katyal and Randhawa, 1983). The dominant soil solution forms of iron are Fe2+, Fe(OHi+, FeJ+(Brady and Wei!, 2002). Singh and Swarup (1996) repotted that the form and solubility of iron (Fe) in soil solution depends upon soil redox potential; in well -aerated, oxidized soil, FeJ+ predominates, while in reduced, water logged soils, the major species is Fe2+. Even though iron is abundant in the earth crust, iron deficiency is observed in calcareous soils where there is high pH and sandy soils which are inherently low in total iron and available iron (Katyal and Randhawa, 1983).

9 3.3.2. Copper (Cu)

Total copper (Cu) contents in soils vary between 10-200 ppm with an average value of around 55 ppm (Katyal and Randhawa, 1983). Copper concentration in soil ranges from 1 to 40 ppm and averages about 9 ppm. Alnwick (1998) reported that copper is absorbed by plants as cupric ion

2 (Cu +), and may be absorbed as a component of either natural or synthetic organic complexes.

Krauskpof (1972) reported that copper shows two valences in naturally occuning compounds.

The valence + 1 is more common in minerals fmmed at considerable depth beneath the earth surface and +2 is compound formed near the sUiface.

Copper concentration in plant tissue ranges from 5 to 20 ppm (Mortedt et.al, 1972). Copper deficiency is observed when its level in plants falls below 4 ppm dry matter Of the micronuUient cations (Cu, Zn, Mn, and Fe) copper is most strongly bound to organic matter (Katyal and

Randhawa, 1983). This explains why copper is deficient in organic soils.

3.3.3. Zinc (Zn)

Total Zinc in soils varies from 1O-300ppm with an average of around 80ppm (Katyal and

Randhawa, 1983). Highly leached sands are usually low in total Zn «30ppm). Lindsay (1979)

2 reported that the active fmm of Zinc in soils is the divalent cation Zn +. The status of Zinc in plants is mostly unrelated to the total Zinc in soils (Katyal and Randhawa, 1983).

Researchers have shown that Zn deficiencies of cereals under rainfed and ilTigated conditions decline in the order of rye> triticale> bread wheat> barely> oats> durum wheat (Cakmak et.al,

1996). Moreover, the depletion of Zn in the soil near the roots suggests that diffusion is important for Zn supply to the plants (White et.al, 1979)

10 3.3.4. Manganese (Mn)

Manganese (Mn) concentration in plants varies much more than any other micronutrient (Katyal and Randhawa, 1983). The nOlmal contents of manganese in plants range from 20 to 500ppm on 2 a dry weight basis. Manganese is available primarily as Mn + and Mn02 in soil (Misra, 1997). 2 He further described that Mn02 can be reduced by root exudates from Mn + which is a possible fOlm absorbed by the transport in root plant membranes.

Manganese toxicity can occur in crops growing on extremely acidic soils. Diversity among wheat genotypes for micronutrient uptake transport, distribution and use has been recognized

(Graham et.al, 1992).

3.4. Micronutrient Interactions

The balance among the micronutrients in the soil as well as with other nutrients affects their availability (Brady and Weil, 2002). For example, soils high in phosphorous levels can depress

Zinc uptake and reduce yields. According to Katyal and Randhawa (1983), the availability of high phosphorous in soils, either native or created through excessive treatment with phosphoric fertilizer has an adverse effect on Zinc nutrition of crops. The antagonistic effect of high phosphorus on Zinc availability is aggravated in calcareous soils. Like Zinc, high phosphorous in soils antagonized iron availability to plants. Getachew sime (2002) rep0l1ed that Manganese content in plants is synergistic with Zinc (plants with highest concentration of Zinc have also highest content of Manganese), calcium is antagonistic with Zinc uptake by plants (Chlopecka et.al, 1996).

11 3.5. Factors Affecting The Availability Of Micronutrients

The soil is a good reservoir for micronutrients. Some contain thousands of pounds of micronutrients per acre and small amounts of other nutrients. Trace elements are released in to soil solution directly through weathering of minerals and the decomposition of organic matter, as well as from ion exchange processes (Brady and Weil, 2002).

Strong leached acid soils are low in most micronutrients (Brady and Weil, 2002). This may be due to their parent materials initially low in the elements, and acid leaching has removed much of the small quantity of micronutlients Oliginally present.

Soil pH, especially in well-aerated soils has an influence on the availability of all micronutlients except chlorine. Under acid conditions, most micronutrient cations are freely available sometimes at toxic levels.

Micronutrients disttibution can be influenced by organic matter (Malo et.al, 1974). This is because properties like CEC and optimum pH vary with organic matter content. Cl·eser et aI.,

(1993) similarly desclibed that organic matter can affect micronutrient availability through complication and chelating processes, holding those nutrients in unavailable forms.

Soil erosion can also influence micronutrient availability (Brady and Weil, 2002). Erosion of topsoil canies away considerable soil organic matter, in which much of the potentially available micronutrients are held. Removal of topsoil exposes sub soil hOlizons that are often higher in pH than the topsoil, a condition that leads to deficiencies of some micronutlients such as Zinc.

Eroded ridges or hill soils are common sites of micronutlient deficiencies in some areas.

12 Soil texture has an effect on micronutrient availability in soils (Brady and Weil, 2002). Sandy soils (coarse textured soils) are most deficient in micronutrients and other essential nutrients too.

Clay soils (fine textured soils) are less likely to be low in plant - usable amounts.

Intensive cropping removes large amounts of plant nutrients during harvest (Brady & Weil,

2002). This accelerates the depletion of micronutrient reserves in the soil and increases the likely-hood of micronutrient deficiencies. This kind of depletion is most common where high yields are produced with the aid of chemical fertilizer that supplies some macronutrients. More over, micronutrient deficiencies and toxicities are often related to the level of those elements in the parent material from which the soil form. Raychaudhuri (2001) indicated that increased yield through intensive cultivation contributes accelerated exhaustion of micronuttients from soils.

3.6. Micronutrient Soil Test

According to Cox and Camprath (1972) soil test helps to separate deficient from non-deficient fields. It also helps for detetmining whether a particular nuttient is limiting or not. Once infOlmation is available, conective measures can be applied.

Soil testing methods differ considerably because of difference in soils, crops and climatic conditions. Hence, various chemical solutions are used for the analysis purpose.

According to Wilkinson et aI., (2000) soil testing for micronuttients is becoming more prevalent worldwide as crop production becomes more intensified. For interpretation of chemical soil tests, all possible information should be obtained regarding locality, topography, climatic

13 condition, parent material, vegetation, ground water level and the presence of impervious layer in profile.

3.7. Leaf Analysis For Micronutrients

Chemical analyses of well-chosen indicator plants provide valuable information about the micronutrient status of soils, especially in extreme nuUitional conditions and, in addition, data on the nuUitional quality of the crops can be obtained simultaneously (Cottenie and Kiekens, 1974).

According to Sillanpaa (1982), plant nutlient concentration data are valuable to successful nutlient management programmes and can be used to help establish nutrient recommendations.

Clitical nutrient concentrations in plant shoot for diagnosis may decrease markedly as the growing season progresses (Romheld and Marshner, 1991).

Leaf analysis for micro nutrients is important because it is considered as the focus of physiological activities. Changes in mineral nutrition appear to be reflected in the concentration of leaf nutlients. Moreover, they are considered the major manufactuling sites of organic substances.

3.8. Micronutrient status of Ethiopian soils

Sillanpaa (1982) repolted that Ethiopia is among copper (Cu) deficient countries. The copper contents Vaty greatly and very low plant and soil copper contents were measured. The Vertic arable soils of Ethiopia are not deficient in Mn, Fe and Cu, where as 22% of the soil samples analysed were deficient in Zn (Pulschen, 1988). Desta Beyene (1983) on his first attempt of diagnosing the micronutrient status of Ethiopian soils pointed out that Fe and Mn were at adequate level, while Zn contents varied through the investigated areas. SiIlanppa (1982) also

14 indicated that the extractable Fe contents of Ethiopian soils have high values. Ethiopia stands clearly on the high side in the "International Manganese field" and in spite of relatively wide variations of Mn contents, no low values were recorded. Another report revealed that there is toxicity of Fe, Al and Mn in high rainfall areas of Ethiopia (Mesfin Abebe, 1988)

15 4. Materials and Methods

4.1. Description Of the Study Sites

4.1.1. General

The study sites of this investigation lie in the nOlthem tip of Ethiopia (Tigray Region) between

12020'N and 14030'N latitudes and 36~ and 41°30' longitudes on the Sudano-Sahelian African dry land zone. The sites also represent the highland (Dega) and the medium altitude (Wein­ adaga). Dogu'a Tembien (2650 m.a.s.!) and Adigudom (1960 m.a.s.!) respectively, lie in these climatic zones. Representative catenas were selected at each site to conduct a comparative study of the morphology, physical, chemical behavior of the major soil units, at different topographic positions, within the study areas.

The study sites have altitudinal, climatic and to some extent vegetation differences. The cornmon thing they share is the nature of their parent material and land use as well. Moreover, the two study sites represent the most cultivable areas of the Region.

4.2.2. Adigudom

Adigudom, the main town of the study area, Rintalo Wajerat Woreda (distIict) is situated at an altitude of 1960 m.a.s.!. It is 44 km away from the capital of Tigray, mekelle toward southern direction.

16 The experimental site is located in Adigudom kebele near Gumselasa, 4km east of Adigudom town, on the Mekalle Plateau in the Southem highlands of Tigray.

In Adigudom, the outcrops are mainly composed of igneous and sedimentmy rocks as the geological setting of Tigray described by BoseIlini et.al, (1997). Among the igneous units, medium grained sized dolerite dominates. The sedimentary units include the Agula shale fonnation, limestone and coguina (fully fossiliferous limestone). The Agula shales comprise alternate layers of calcareous marls. Shales and limestone may contain minor inclusion of dolerite. The rocks give rise to stony, calcareous and fine textured soil parent materials. Due to erosion, the majority of the sedimentary rocks have been removed from the surface. Erosion resistant rocks came in to dominance.

The vegetation of Adigudom areas can be classified as "Montane Savana" and was covered partially by deciduous wooded grassland (HTS, 1976). The most important shrubs and trees are

Acacia sp., Ficus sp., EuphOliba abyssinica, Cordia african, Croton macrostachys and Olea europea. The most important grasses and trees include Andropogon sp, Hypanhena sp, Eragrostis sp and Panicium sp, Rumex nervosus, Acacia sp., and unpalatable grasses such as Atistida sp. and Ruderals and Ephemerals mostly replaced the original trees. Rumex nervosus is ubiquitous on most soil types being left within fields as well as at field boundaries to effect some measures of soil erosion control.

Adigudom has a cool tropical semi-mid climate (passil Kebede, 2002). It is characterized by the droughts, which occur at unpredictable basis. The weather in Adigudom is influenced by the

Inter Tropical Convergence Zone (ITCZ). During some part of the year, Adigudom receives

17 warm and dry winds from the Sahara, resulting in dry season. The sun's solar radiation is very strong.

The northward movement of the ITeZ over Ethiopia between March and May encourages the progressive movement of the monsoon air masses from the southwest. Very intensive rains, patticularly in regions situated at high altitude accompany this movement. In July, the large low- pressure area over the Indian Ocean and the Arabian sea dominates the air flow and most of the country is under the influence of the southwest monsoon.

According to NMSA (1998), rainfall in Adigudom shows seasonal variation. The yearly average rainfall is 511mm (SAERT, 1996). Rainfall at this area is monomodal, with more than 85% of the rain falling within a peJiod of four months from June to September. The n01th and south oscillation of the ITeZ produces a highly unpredicted and erratic annual rainfall pattem at

Adigudom.

Distributloln of Rainfall at Adlgudom

1200 '-:-~~~""Z'=--:C:"-'''~~7T,.TT'~~~'''l E 10001+9+~~~~~++ E 800 -P6$~~~~*~ ~ 600 -lc+'~~ /Ill Annual Rainfall/ 400 200 o ~ ~ # ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~* ~ ~ ~ ~ ~ ~ Year

Fig. I: - Yearly rainfall at Adigudom ( II years) (Source: National Meteorological Service Agency: Personal Communication).

18 According to HTS (1976), the temperature in Tigray is mainly determined by altitude. In the low

lands, the average annual temperature is above 25.30C, while in the highlands like the study sites

the average temperature is around 22°C. In general, the average temperature drops about 6°C. per

100m altitude.

The main crops grown in Adigudom are: wheat, barely teff, sorghum, millet, maize, pulses and vegetables (Mintesnot Behailu, 2002). Sorghum and maize are planted at onset of the rainy period while other crops are grown at the beginning of the rain in March.

In Adigudom a distinct soil catena is described considering the different topographic position as the principal factor determining soil distribution within the catena. A schematic representation is given in Fig. (2). Leptosols are fOimed in the weathered mantle of upper slopes on the limestone or doletite. Vettic Cambisols are dominant on the pediments where as Vettisols are developed on the lower part of the pediments, while Lllvisols are common on the lower part of the valley.

"0en .~ "0en 0 - 1 en U 0 3 t) -en en '13 '13 t) -0 ~ " ~ '13 .~ "0 > ~ >>-"" OJ .€ "> Fig.2:- Schematic representation of the soil catena at Adigudom

19 4.1.3. Dogu'a Tembien

Dogu'a Tembien (district) is situated at an altitude of 2650 m.a.s.l. It is 50 km away from the capital of Tigray, Mekelle. The experimental site is located in Kebele Selam Fmmers'

Assocation, which is 3 km away from Hagereselam towards the east direction.

The geological formations of the area are of the Mesozoic age (Antalo limestone and Amba

Aradom sand stone) or tertiary basalt flow with inter-bedded lake deposits and sub horizontal layers (Nyssen 1996). One also finds some quatemary formations, consisting of alluvium and colluviums. The experimental site is situated on the Trapp basalt.

According to HTS (1976), the height of Dogu'a Tembien is surrounded by woody type of vegetations: to the west more rainy, deciduous woodland; to the east, Montana evergreen thicker and sClUb also occupies of the Geba and Agula livers. The dominant herbaceous species, observed in and around arable land close to Hagerselam, on basalt - derived soils are:

Amaranthus hybrid us, Bidens sp; Bromus sp; Galinsoga parviflora, Rumex peguaertu, Rumex nervosus, Scorpiurus muricatus, Tagetes minuta, Trifolium camperstere and Trifolium polystachium (Nyssen, 1996). The tree species encountered in Dogu'a Tembien are: Acacia sp.,

Euphorbia (condelabra type), Ficus vasta. Moreover, Euc!yptus camaldulensis is the most prefelTed species because of its rapid growth and straight trunk often used as timber.

20 Rainfall at this site is also a monomodal falling within a period of four months from June to

September. The yearly average rainfall is about 750 mm.

800·· : 700 E 600 -S 500 1111 Annual Rainfall I ~ ·iii 400 0:: 300 200 100 0 1995 1996 1997 1998 1999 2000 2001 2002 year

Fig.3: - Annual Rainfall of Hagereselam (town of Dogua Tembien) (1995-2002).

The major crops growing in Dogu'a Tembien area are more or less similar with that of

Adigudom. The major crops include: wheat, barely, teff, sorghum, millet, maize pulses and vegetables.

In Dogu' Tembien a distinct soil catena is desctibed with a topographic position as the principal factor determining soil distJibution within the catena. A schematic representation is given in Fig.

(4). The topography results in a sequence of soils along the slope.

21 Leptosol - Regosol - Vertic Cambisol - Veltisol Catena is typical in Kebele Selam Farmer's

Association.

~ 0 '"0 ~ 0- (!) ~ ~ ....:I 0 0 '"0 O( u .~'" -"l (!) 0 ~ ~ 'E 1 .€ >u ">

Fig .4: - Schematic Representation of the Soil Catena in Kebele Selam Farmers' Association.

EUd o 11l ..

LEGEND Profile p,ts • Carrblsols A Vertisols [:=J SludyWeredas [:=J Tlgray Region "

Fig 5: - Map of Dogua Tembien and Adigudom Wereda in Tigray Region (Source: EARO)

22 4.2. Preparation and Laboratory Analysis of Soil Samples

Soil samples were taken from each horizon of the representative profiles of the two soil types.

Composite smface soil (O-20cm) was also taken at spots adjacent to the pits. Physical and

Chemical analysis was calTied out in Mekele university and the National soillaboratOlY. Six sub samples were taken and the composite sample placed in plastic bag. The extra portions of the smface samples were used for green house expeliment to observe con-elations between soil and plant test values. The soil samples were put in polythene bags with proper identification tags.

The soil samples were air- dried at room temperature by spreading on plastic trays. On drying, they were ground in the glinding machine and sieved through 2mm sieve.

The profiles were dug to a depth close to loS m. Soil charactelistics were recorded standard form for profile description. Profile descliption was done directly in the field just light after profile excavation. Characteristics like location of the profile, slope, rock out crops, land use, soil depth, color, root distribution, horizon boundaty and consistence were described.

4.2.1.Physical Analysis

4.2.1.1. Bulk density

Core samples collected from the different soil horizons were first weighed (at field moisture condition) then oven dlied at 10Soc and weighed again (oven dry wt). The bulk density was then detennined by dividing the weight of the dry soil over the volume to the con'esponding core used to sample the soil. The values are given in g.cm-3 (Dewis and Freitas, 1984).

23 4.2.1.2. Texture and Soil Moisture

The Bouyoucos Hydrometer method was used to detelmine the texture (Bouyoucos, 1951). Fifty gm air-dlied soil sample, which had been passed through 2 mm sieve, was soaked with 50 ml­ distilled water for 2% hour. 20ml of 30% H202 were added and the contents heated on hot plate at

900C for 2% hour to destroy the organic matter. Then after 20ml of 5% sodium hexametaphosphate (Calgon) was added and the suspension was then transfe11'ed to the hydrometer jars stilTed for 5 minutes, and the volume increased to the one litter mark. The hydrometer and temperature readings were taken at 40 seconds and 2-hour intervals to calculate the silt and clay percentages, respectively. % of sand was calculated by subtracting silt and clay percentages from 100%. Soil moisture content was determined gravimetrically by dtying a soil sample in an oven at 1050C for about 24 hours or to a constant weight. Finally, the moisture content was calculated in percent by weight.

4.2.2.Chemical Analysis

4.2.2.1. Percentage of Organic matter and Organic Carbon

The percent organic matter and organic carbon of the soils were determined, using the Wet

Oxidation Method (Walkley and Black, 1934). The percentage of organic carbon was calculated from the titration values, and multiplied by 1.724 to obtain % organic matter.

4.2.2.2. Total Nitrogen

Total nitrogen in the soil samples was determined using the micro - Kjeldahl digestion and distillation method through destruction of organic matter by oxidation where the distillate was

24 titrated using a O.IN HCI to pink end point. Finally, total nitrogen content of each sample was calculated based on the readings obtained from the titration and repOited as percent total nitrogen.

4.2.2.3. Available Phosphorous and Carbonate

The available phosphorous for all the soils was determined using Olsen's O.5M NaHC03 extraction solution (adjusted to pH 8.5) (Olsen, et aI., 1954). Carbonate content was measured by the potentiometer or pH meter titration method where the pH meter was calibrated with buffers of pH 4.0 and 7.0. The pH meter was immersed in to the aliquot and tirated with standard HCI to end pH 8.4 and 4.4 for carbonates. The amount or volume the titrant to end pH 8.4 and 4.4 were recorded and used to calculate the carbonate contents.

4.2.2.4. Exchangeable Cations (Ca, Mg, Na and K)

Exchangeable cations (Ca, Mg, Na and K) in the soil were determined using Ammonium Acetate method (Black et aI., 1965) from a mixture of 5 gm soils and 5 gm acids washed sand percolate with 250 ml 1M ammonium Acetate. They were determined by Atomic Absorption spectro­ photometer using an air acetylene flame and the values were calculated in meqf100gm soil .The soil was previously leached with 1M Ammonium acetate, using ammonium acetate method

(Page, 1982), was successively washed with 25ml portion of 95% Ethanol using a total of 100ml of Ethanol. Adsorbed Ammonia was then replaced with sodium (Na) by extracting the soil with

100ml of 10% sodium chloride (NaCI). Ammonia was detelmined after distilling in 0.2N sulphuric acid and titrating the excess acid by O.lN sodium hydroxide. After extraction, distillate was read using AAS and values calculated in ppm.

25 4.2.2.5. Available Micronutrients (eu, Fe, Mn, & Zn)

The extractable (available) micronutrients (Fe, Cu, Zn and Mn) were extracted by DTPA

extraction solution, adjusted to pH 7.3 (Lindsay and Norvell, 1978). 20 gm of air-dried soil

sample less than 2 mm was placed in a conical flask, to which 40 ml of the DTPA extraction

solution was added and the mixture was shaken for two hours in a reciprocal shaker and the

suspension filtered. The quantities of the extracts were measured with an Atomic Absorption

Spectrophotometer in comparison with standards at 248.3nm, 279.5nm, and 324.7nm and

213.9nm wavelength for Fe, Mn, Cu and Zn, respectively. 1ml of 0.1 % lanthanum was added to

prevent condensed phase intelferences.

4.3.Green House Pot Experiments

To correlate soil test value with nutJient uptake by plants, greenhouse pot expeJiment of barely

crop C!.:!oredum Vulgare - VaJiety Local) was conducted for the two soil types namely Cambisols

and Vertisols from Adigudom and Dogu'a Tembien. The choice of the crop was based on the

crop of greater agJicultural importance in the two sites, adaptability, and ease of operation. Nine

gram of barely was used per pot. This was the conversion from the actual recommended seeding

rate (Eighty five Kilogram of barely per hectare). On the other hand ten gram of phosphorous and

five gram of Nitrogen were used. This rate was the conversion from the actual fertilizer

application rate (i.e DAP -100 kg/ha; Urea 50 kg/hal. The Vertisols and Cambisols from each

site were replicated 3 times and have a total of twelve (12) observations. The statistical design

used to layout the expeJiment was Complete Randomized Design (CRD).

26 4.4. Green House Pot Experiment Operation

The soils for the experiment were ground by hand up to the size which was suitable for the

growth of the barely crop. Three kilogram of soil per pot was used in the experiment. Date of

sowing was on 9-12-2003.

Recommended Seeding and Fertilizer rates

Rec. Seeding rate A.F.R

Green house Barely 85kg of barelylha g P per pot (l0.4 glpot)

g N per pot (5.2 glpot)

A.S.R

Barely per pot (8.86 g/pot)

4.5. Plant Sample Preparation for Chemical Analysis

The upper, most recently matured, healthy leaves having no environmental or insect or pest

damages were collected from green house just at 50% blooming stage. After sampling, the leaf samples were brought to the laboratory and immediately washed with distilled water to avoid

danger of leakage of nutrients like K and Ca. After washing, samples were dtied as rapidly as

possible in paper bags in drying cabinet at 65°C for 24 hI'S to minimize chemical and biological changes. The dry leaves were ground with a hammer mill of pure carbon steel to pass 1 mm sieve. The ground leaves were stored in a polyethylene bags and aerated until they were analyzed.

27 4.6.Ashing and determination of Plant Cll, Fe, Mn and Zn

The content of dry samples (lgm) was determined by drying the samples in aluminum dish over night at lOSoC in an oven. The oven dry samples were put on furnace to gradually raise the temperature up to 4S0oC for 6 hours to destroy the organic matter and maintaining this temperature overnight. The bumed material was transfel1'ed in to 200ml Erlenmeyer flask to which was added 20ml of 20% RN03• Then after the acid treated sample was heated on hot plate to boiling and cooled. The sample was filtered through a whatman No.1 filter paper in to a

100mi volumetric flask. The contents were washed until 90ml of the filtrate were collected, and brought to volume with distilled water (Rouba et aI., 1989). Cu, Fe, Mn and Zn were measured directly on the main sample solution with Atomic Absorption Spectrophotometer as on soil extracts that gives the values in ppm.

28 5. Results

The statistical evaluation of the micronutrient status of each soil in the two regions was based on two analyses; the soil and the plant grown on the soil. Linear regression graphs are used to present the results of both analyses simultaneously. Further more, the cOlTelation between the results of soil and plant analyses are considered a good measure for judging the reliability of the results. The higher the con'elation, the better the link between the soil and plant analyses.

Therefore, the regression and correlation analyses were canied out using computer Program

SPSS for windows, 2000.

5.1. Soil Analyses

Weighted average bulk density increased down slope at Dogua Tembien Soil Catena. Weighted average values of bulk density for Cambisols and Vertisols were 1.12 gm.cm,3 and 1.21 gm. cm,3, respectively (Table AS (b)). At all positions, bulk density generally increases with increase in depth. At lower part of the field, where sUlface materials are enriched with alluvial sand and silt fractions the weighted bulk density average increases gently (1.21gm.cm'\ Values for

Cambisols and Vertisols ranged between 0.8 to 1.25 gm. cm,3 and 1.02 to 1.31 gm. cm,3 respectively (Table AS (b)). These values are generally lower than bulk densities reported in other part of the world.

Bulk density values follow regular pattem along Adigudom Catena. At all positions, bulk density increase with increase in depth. Compalison of upper and lower positions indicated that Cambisol has relatively higher percentage silt and lower sand. On the contraly, Veltisol has relatively higher percentage sand and lower silt. As a result, the soils have more or less equal average

29 weighted bulk density (1.S2gm. Cm,3) (Table AS (b)). Values for Cambisols and Vertisols ranged between 1.27 to 1.63 gm. Cm,3 and 1.37 to 1.6gm Cm,3 respectively.

Comparison of Dogua Tembien and Adigudom Vertisol indicated that Adigudom has relatively higher average weighted bulk density than Dogua Tembien (Table AS (b)). Similarly. Cambisol at Adigudom has higher average bulk density than Dogua Tembien. This higher average weighted bulk density is due to higher silt fraction.

All holizons in Dogua Tembien are clay (Table Al and A2). Average clay contents increase from the upper to the lower part of the field (Table AS (a)). The Vertisol has the highest fractions in the Catena. At Adigudom. the Vertisol has clay horizons while Cambisol generally ranging between clay to silt clay (Table A3 and A4).

Dogua Tembien Vertisols generally comptise of the highest clay fractions than the Veltisols at

Adigudom. Silt fraction value of Cambisols is higher than vertisols.

Comparison of average silt fractions of Adigudom and Dogua Tembien Vertisols indicated that

Adigudom has relatively higher silt fraction than Dogua Tembien (Table AS (b)). In similar way.

Cambisol has relatively higher silt fraction. This higher silt fraction is due to the deposition of relati vely higher coarser stlUctures on the sUiface of the upper position. Therefore. all in all texture ranges between silt clay to clay. Silt propOitions are highest at Adigudom compared to

Dogua Tembien.

Compared to Adigudom. Dogua Tembien Cambisols has relatively higher sand fraction. This higher sand fraction is due to the down ward movement of coarser mateJials from the upper positions.

30 At Dogua Tembien average carbonate content decrease from the upper to the lower pmt of the field (Table A5 (c)). Maximum carbonate concentration along the catena was observed at the

Cambisols of Adigudom. This higher Carbonate concentration was due to the relatively higher deposition in the parent matelial (Calcite). At Adigudom Carbonate level varied from carbonate free (Veltisols) to a relatively higher carbonate level (Cambisol) (Table A3 and A4).

pH (H20) at Dogua Tembien ranged from7.4 (high alkaline reaction) to 8.6 (velY high alkaline reaction) (Table AI)' All of the soil horizons had alkaline reaction. No dramatic pH differences were observed between individual soil h011zons. There was a general trend of pH Iising gently down the horizons in Vertisols but remained unchanged for Cambisols.

At Adigudom, pH of the soil decreases from the upper to the lower pmt of the field. pH (H20) for

Vertisols ranged between 8.4 (high alkaline reaction) to 8.6 (very high alkaline reaction). The pH for Cambisols ranged from 8.5 (high alkaline reaction) to 8.8 (velY high alkaline reaction).

Compared to Dogua Tembien higher pH value was observed at Adigudom Cambisols with in 65-

95 em depth. The values of organic matter percentage of Dogua Tembien soils (Table Al and

A2) ranged from 1.7 (Low) to 2.65% (Medium).

Organic matter increases from upper part to the lower pmt of the field and has values ranging from 1.84 (Law) to 2.31 % (Medium). CIN ratio also increases from the upper to the lower part of the field. Most horizons have values ranging between 0.06 (velY low) to 0.17 % (Low). These values fairly correspond to the organic matter distribution, for the obvious reason that the organic matter is the major source of these elements.

31 At Adigudom, percentage organic matter values ranged from 0.8 (very low) to 2.34% (Medium).

The highest organic matter content was found at Ap horizon of Adigudom Cambisols (2.34%).

The organic matter depends on the crop residues that turned into the soil after harvesting.

Compared to Adigudom, Dogua Tembien had relatively higher amount of organic matter. The presence of high clay content at Dogua Tembien contributed to the maintenance of the soil organic matter. In addition, intercropping with legumes is practiced in Dogua Tembien. Surface soils have the higher values and the deeper ones the lowest content of organic matter.

The distribution of total nitrogen in Dogua Tembien ranged between 0.11 to O.lS% (Low) (Table

Al and A2). Total nitrogen is related with organic matter (AI and A2).

At Adigudom, the total nitrogen distribution ranged from 0.06% to 0.17 % (low) (Table A3 and

A4). Total nitrogen values at the two sites were generally low.

Average CEC was comparatively higher at Dogua Tembien catena than Adigudom. Ca and Mg are the dominant cations. Average exchangeable Na (Naex) and K (Kex) decreased from the upper to the lower pmt of the field. (Table AS (b)).

In Adigudom, average CEC was comparatively lower than Dogua Tembien. The average CEC increases down slope ranging from 32.0S-to 48.27-meq/100 gm of soil. Higher average exchangeable Na (Naex) is found at Adigudom Vertisol (1.13 meq/l00gm of soil). The average exchangeable K (kex) decreases down slope from O.SS-to 0.8-meq/l00 gm of soil (TableAS (b)).

Available P contents at Dogua Tembien are low except the AP horizons of Cambisol, which has higher value (5.4 ppm). Similarly, all soil horizons of Adigudom consist much lower amounts of

32 available phosphoms, which ranges from 0.2 to 1.4 ppm. Relatively higher amount of available phosphoms is found at Cambisols of the sUiface soil (9.8 ppm)(Table AI3).

In Dogua Tembien average Fe and Mn content, decrease from the upper to the lower patt of the field (Table AS (d)). The distribution of Zn and Cu however is quite the opposite. The concentrations of extractable micronutrients for Dogua Tembien Vertisols range from 8.96 -

1O.14[[m, S.82-8.88ppm, 0.04-0.1ppm and 2.48-2.64 ppm for Fe, Mn, Zn and Cu respectively.

The extractable micronutrients for Cambisols range from 8.86-12.16ppm, 9.10-17.8ppm, 0.08-

0.24ppm and 0.98-2.16ppm for Fe, Mn, Zn and Cu respectively (Table Al and A2).

In Adigudom average Fe, Mn and Cu increase from the upper to the lower part of the field (Table

AS (d)). Average Zn decrease down slope. The concentration of extractable micronul1ients in

Adigudom Vertisols range from 11.00 -14.48 ppm, 5.96 - 10.28 ppm, 0.14 -0.18 ppm and 1.88-

1.96 ppm for Fe, Mn, Zn and Cu respectively. The concentration of extractable micronutrients in

Adigudom Cambisols range from 3.5 - 9.74 ppm, 2.66 - 1O.72ppm, 0.06-0.36ppm and 0.1-1.22 ppm for Fe, Mn, Zn, and Cu respectively (Table A3 and A4).

In both sites, the concentration of Zn in all holizons is found to be velY low as compared to Fe,

Mn, and Cu (Table 1,2,3 and 4). Next to Zn, Cu concentration is low in all holizons. Highest concentration of Mn is observed at Ap - hodzon of Cambisols in Dogua Tembien. Highest concentration of Fe is found at Adigudom Cambisols of Ap - hodzon. Fe concentration decreases with increasing depth in Vertisols at Adigudom. In DoguaTemein, Mn concentration decreases wi th increasing depth at Vertisols.

33 For categorization of soils in to deficient, sufficient, and toxic levels the deficient values are taken as 0.75 ppm soil for Cu, 2.5 -4.5 ppm soils for Fe,S -7 ppm soil for Mn and 0.5-1.00 ppm soil for Zn (Cox and Kampatth, 1972)

Table1: - DTPA extractable micronutrients distribution of Dogua Tembien Soil

Catena

Vertic Cambisols Depth (em) Extractable micronutrients (ppm)

Fe Mn Zn Cu 0-9 12.16 17.86 0.24 2.16 9-40 8.86 9.10 0.08 1.98

Pellic Vetrtisols

Depth (em) Fe Mn Zn Cu 0-10 9.22 8.88 0.04 2.48 10-65 8.96 6.60 0.10 2.48 65-140 10.14 5.82 0.06 2.64

Table2: - DTPA extractable micronutrient distribution at Adigudom Soil Catena

Vertic Cambisols

Depth (em) Extractable Micronutrients (ppm)

Fe Mn Zn Cu

0-15 7.60 10.72 0.18 1.22

15-30 9.74 9.82 0.36 1.10

30-65 3.92 5.68 0.08 0.30

65-95 3.50 2.66 0.06 0.26

34 Pellic Vertisols

Depth (em) Extractable micronutrients (ppm)

Fe Mn Zn en

0-25 14.48 6.94 0.18 1.88

25-75 13.90 5.96 0.18 1.92

75-105 11.00 10.28 0.14 1.96

The hierarchical Cluster analysis method has shown that there is strong similarity between

Vertisols and Cambisols in Dogua Tembien. The next similar soil type is Vertisols, then

Cambisols from Adigudom (see Fig.6 below).

Hierarchical Cluster Analysis

Rescaled Distance Cluster Combine

CASE o 5 10 15 20 25 Lata) Num X"--__--'L' ___ --'Ly ___ --"-, ___ -"-x ___ ..Lx

Dogua Teillbiarl VarUs"i bagun reillbior\ emllhl.,,) Adigudorn Wrtiso) Adigudorn Calnbisol

Fig.6: - Dendrogram using Average Linkage (between Soil types)

35 Chi-square test statistics has showu that perceutage CaCO] was significantly different for both

soil types at (P

Test Statistics a,b

C h i- S qua fe d f Asymp.Sig. pH 5.435 1 .020 EC 1 .905 1 .1 67 San d % 6.4 7 2 1 .0 1 1 S ilt% 7.7 0 3 1 .006 C lay% 1 .1 72 1 .279 M .C% .329 1 .566 Bulk-Density 6.4 2 6 1 .0 1 1 Na .059 1 .808 K .1 65 1 .685 Ca 5.955 1 .0 1 5 M 9 8.077 1 .004 C E c 8.077 1 .004 8as.Sa% .107 1 .744

CaC0 3 % .1 66 1 .684 T.N % .809 1 .368 O.C % 2.389 1 .1 22 C IN .553 1 .457

AV - P 4.520 1 .033 o .M% 2.389 1 .1 22 Fe p p III .007 1 .935 M n ppm .165 1 .685 Zn ppm 1 .5 1 5 1 .218 Cup pm 8.105 1 .004 a. Kruskal Wallis b. G ro u p in 9 Varia b Ie: Dog u aTe III b ie nan dAd ig u do m

ANOV A has shown that Mn contents are significantly different between soil types of each region at (P

36 Table 4: - Analysis of V m1ance between and within soil types of each region AIIOVA . ··ISll~ofSq~~r~-T I ...... I'L Sig. FeJlpm types of I .917 :f, .:::ar :a~;;;e:~o~Oil ~152 1 M::: 0.647.. I··I 0.606 ! I V\l1Ihin soil types of . I each region I 8874 8 II.. 11 09.25 Total I 11 026.917 11 ' I. . ... 1 ... 15.59810.023

I II I . I I ,l:n--ppm Between soil typesof I i J ., .. . each region .. . I 150.91 L ..1 31.50.396 .12.21_1\ 0:164 .. es V\i1thin soil tyr of ...... II each region 182 ..i 8 L 22.75 I L Total 332.917 11 I Cu--ppm Between soil types of ... ········~ach;egiOn . ..- ·r I 0.917 .. I .3-1 0.306 }0.1531 ()E25.1 , I i II' V\l1Ihin soil types of . .. I I . each region 16 r 2 i.. Total I 16.917 I 1~ I i Spearman's correlation analysis (TableA6) has shown that Fe is positively and significantly couelated with Na (r = 0.608*) and negatively and significantly correlated with CaC03% (r=-

.867**). Mn is positively and significantly c011'elated with K and av.p (r=. 741**) and

(r=0.725**) respectively, negatively, and significantly con'elated with bulk density (r=-.592*).

Cu is positively and significantly couelated with sand %(r=0.627*), Clay% (r=0.639*), Ca (r=

0.775**). Mg(r=0.939**), and CEC (r=0.935**) but negatively and significantly con'elated with pH (r=-.625*) and Silt % (r=-0.898**).

37 5.2. Foliar Analysis

The result of foliar analysis showed that barely has marked difference in their micronutIient

uptake ability from the soil under controlled and uniform conditions. For categorization of leaves

into deficient, sufficient and excess levels the deficient values were taken as < 4 ppm for Cu, < 50

ppm for Fe, < 20 ppm for Mn and < 20 ppm for Zn (Jones, 1972). Accordingly, foliar analysis of

barley (Hordeum vulgare) grown on Vertisols and Cambisols of both sites have shown that

available Fe, Mn, and with the exception of Zn at Dogua Tembien Cambisols were at sufficient

level whereas Cu concentration in both soil types was at deficient level. The soil types in both

regions along the catena have low available P. Therefore P-Cu antagonism is not expected.

Foliar analyses of barely have shown differences in nutIient compositions in each catena of both

regions. The available Fe, Zn and Cu were insignificantly but positively related to plant Fe

(r=O.4), plant Zn (r=0.105), and plant Cu (r = 0.949) respectively. However, soil Mn was

positively and significantly conelated to plant Mn (r = 1.0**) (TableS below).

Table 5:-Conelation Analysis showing relationship between Pant and Soil nutrient concentration

Plant Fe Plant Mn Plant Zn Plant Cu

Spearman's rho Soil Fe 10.4 -0.8 1.000" 0.105

SoilMn -0.8 1.000" -0.8 0.105

Soil Zn -0.632 0.105 ~.105 1.000"

SoilCu -0.4 -0.2 ~.4 0.949

**Con'elation is significant at the 0.01 Plant versus soil Fe has shown that there is 38% dependency (R-square=0.38) of Fe -plant on Fe

-soil. Plant versus soil Mn has also shown 61 % dependency (R-square=0.61) of plant Mn on soil

Mn (Fig.? (a) and (b»

38 In the same way, plant eu concentration versus soil eu has shown 94% dependency (R-square

=0.94) of eu concentration in soil. Lowest dependency was observed between plant Zn and soil

Zn concentration (R-square=O.OI) (Fig.7 (d)).

11.(0 13CD 17m ail Fe():p1j

Fig.7 (a): -Regression analysis showing relationship between Plant_Fe and SoiLFe values

39 PI!V1t M1= 39.89 + 3.01 • Soil M1 R-!q.we = 0.61 "C 7fiOO iii ::::I -s: -..::::I 71).00 'C 'C 3 '-" ffiOO

00.00

55.00 J.. I ~...... -.- I I I I 7.00 am 9.00 10.00 11.00 1~00 Soil M1 (ppm)

Fig.? (b): -Regression analysis showing relationship between Plant_Mn and Soil_Mn values.

40 ,------~--~--~

Plant Zn = 28.32 + -2.10' Soil Zn R-Square = 0.01 32.00 "tI III ::::I

~ 30.00 ~ ---"C ' "C 3 -- 28.00

26.00

24.00

0.30 0.40 0.50 0.60

Soil Zn (ppm)

Fig.7 (c): -Regression analysis showing relationship between Plant_Zn and SoiLZn values.

41 4.00 Plant Cu = 2.79 + 0.33' Soil Cu R-Square = 0.94 "C iii ::::I.. Q 3.80 ...... 'C 'C 3 '-' 3.60

3.40

-"'-I'~-----I-"'------'-I--'~---'I'" ------.I'~--' 1.50 2.00 2.50 3.00 3.50 Soil Cu (ppm)

Fig.7 Cd): -Regression analysis showing relationship between PlanCCu and SoiLCu values.

The hierarchical Cluster analysis of barely grown on Cambisols from Dogua Tembien is much similar with Cambisols from Adigudom. However, barely grown on Vertisols from Adigudom gave similar results to Vertisols from Dogua Tembien (Fig.8 below).

42 Hierarchical Cluster Analysis Rescaled Distance Cluster Combine

CAS E :, It) 1 ~., Hurn

Do.tlUii Tcrrbl!!ri Cilhlbhlol /wiyut.lorr'l Cflrilbit:ol

Do~Uti Tc-mbieri Verli!:iL'l Adiyudon'1 Verli!:tcl J

Fig.S: - Dendrogram lIsing Average Linkage of barely grown on Vertisol and Cambisol.

43 6. General Discussion

6.1. Soil Reaction (pH)

All the sUiface and subsUiface soil pH for Veltisols and Cambisols of Dogua Tembien and

Adigudom are alkaline (7.4 - 8.8) (TableA1 and A2). The soil reaction as a function of depth in the study sites is depicted in Tables (AI and A2). Commonly, sUiface pH values of Vertisols are

7.0 - 8.0 (Dudal, 1965). However, continuous cultivation of Vertisols can lead to an increase in sUiface soil pH by of bringing up the subsoil material (Hussien et.al, 1992). In the study areas, the highest pH value was found at the depth of 65 -95 cm for Cambisols at Adigudom. The

increased pH at this depth probably can be associated with the accumulation of HeO'3 from

CaC03 dissolution and root respiration.

6.2. Electrical Conductivity

Excessive salts (Na, K, Ca and Mg) hinder crop growth, not only by the effects of toxicity but also by reducing water availability through the action of osmotic pressure. Nutrient uptake may also become unbalanced (Fassil Kebede, 2002). An analytical result for Dogua Tembien and

Adigudom confirms that EC range between 0.02 - 0.365 ds/m and 0.04 - 0.281 ds/m respectively

(TableA1 to A2), in which the salinity effects are mostly negligible for most plants. Another report by Fassil Kebede (2002) confirmed that 95% of the analyses of Vertisols at Adigudom have EC values ranging between 99 and 198 ~S cm -I which has negligible effect for most plants.

44 6.3. Available Phosphorous

The amount of available phosphorous in Dogua Tembien and Adigudom range from I - 5.4 ppm and 0.20 -1.20 ppm respectively. The distribution of available phosphorus is low. The low result of available phosphorous is associated with degree of weatheling and poor management of soil.

Moreover, at high pH, P is precipitated as insoluble calcium phosphate. This low result is in agreement with the report by Piccolo and Huluka (1986).

6.4. Total Nitrogen

The amount of total Nitrogen in both soil types in both studies areas ranged from 0.062 - 0.174%

(very low - low). This is in agreement with the repOlt by Fassil Kebede (2002), which ranged from 0.01 to 0.25% in Vertisols of Adigudom. Total nitrogen was low directly associated with low level of organic carbon because of continuous cultivation of the land.

6.5. Soil Organic Matter

The percentage distribution of soil organic matter in both study sites ranges from 0.8 -2.65%

(velY low - medium). According to Singh (1954), in the tropics and for soils with a long history of cultivation, organic matter can be velY low, e.g.0.3% in India and in Gezira soil in the Sudan

(Robinson et.al, 1970). Organic carbon is usually low in soils when they are cultivated continuously. Deforestation has been held as one of the major factor contributing to organic matter degradation through exposing the soil for various agents of erosion. In addition, the organic content of the soils of the study areas is low due to the wide spread use of dung and crop residues for energy.

45 6.6. Soil Parameters and Micro nutrient Interactions

6.6.1. Texture and Micronutrients

Sand and clay fraction was significant and positively related with extractable Cu (Table A6).

Lower values of extractable micronutrients were observed where there is a higher sand fraction.

Highest extractable Fe and Mn were observed in Vertisols of Adigudom with low sand fraction at lower position of the catena and Cambisols of Dogua Tembien with low sand fraction respectively. According to Brady and Wei! (2002), Sandy soils are low in most micronutrients.

Clay fraction is positively and significantly related to Cu concentration in the soil (TableA6).

6.6.2. pH and Micronutrients pH was negatively con'elated to all extractable micronutrients analyzed in the study areas. Similar result was reported by Getachew Sime (2002). Lindsay (1979) descdbed that the bioavailability of metallic micronuttients decreases with increasing pH. pH was inversely and significantly con'elated to extractable Cu and insignificantly with the rest of extractable micronutrients

(TableA6). Therefore, a general increase in pH fUlther worsened the low status of extractable Zn.

This is in agreement with the report of Getachew Sime (2002).

The solubility is for Fe is much greater than Zn, Mn or Cu under decreasing pH. This is in agreement with the report of Lindsay (1979). In general, the concentration of Fe was highest, followed by Mn. Lowest extractable values of Fe, Mn, Zn and Cu were observed at high pH (8.8) at Adigudom Cambisol. Barak and Helmke (1993) desclibed that at high pH both Ca and Mg can replace Fe, Cu and Zn from soil solution complexes and from adsorption sites on the soil.

46 6.6.3. Available Phosphorus and Micronutrients

Available P in both Catenas was positively and not significantly related to Fe, Zn and Cu concentrations and positively and significantly con'elated with Mn (Table A6). The amount of available P in all positions of the study areas was low (Table A6) hence, it couldn't be able to antagonize the extractable micronutrients. There was decrease in extractable Zn. Bell et.al (1991) reported that P-Zn antagonism occurs only under excessive P fertilization or when the amount of

P in the soil is high.

6.6.4. Exchangeable bases, CEC, base saturation and micronutrients

Exchangeable Ca, Mg CEC were positively and not significantly related with Fe and Mn (Table

A6). Fe was also positively and insignificantly cOlTelated with percentage of base saturation.

However, Zn was negatively and significantly con'elated with Ca, Mg and CEC and positively and insignificantly related with base saturation percentage (Table A6), where as Cu was positively and significantly related with Ca, Mg and CEC and positively and insignificantly related with base saturation percentage (Table A6). The extractable Zn markedly decreased with increasing Ca and Mg. This is because of the competition of Ca and Mg, which are preferentially adsorbed on exchange sites. Havlin et.al (1999) desclibed that micronutrients cannot compete with basic cations on the exchange sites due to their lower diffusion coefficients to CEC.

According to Down and Vlok (1983), the relatively high value of stability constants of Ca implies that the metal can compete with Zn and Mn in ion exchange processes.

47 6.6.5. Percentage of OC, TN, and Micronutrients

The highest concentration of % OC was observed in Vertisols of Adigudom at Ap- horizon.

Organic carbon was positively and not significantly related to extractable Fe, Mn, Zn and Cu

(Table A6). These insignificant con'elations were due to very low organic carbon (Table A6).

Havlin et.al. (1999) described that cultivated lands have less organic matter than virgin lands.

Moreno et.al. (1996) repOited an increasing amount of micronutrients with increasing organic matter in soil, which is due to the fact that the organic matter serves as micronutrient reservoir.

In almost all position of the catenas, OC% was very low OC% is positively and insignificantly correlated to extractable Fe, Mn, Zn and Cu (Table A6). This insignificant con'elation is because of the organic carbon is generally low. Wilkinson (2000) reported that bioavailability of micronuuients increases with the decomposition of organic matter that results on loweting the soil pH. The pH couldn't allow the complexation of the micronutrients by organic matter. Simes

(2000) reported that, micronuttients could be complexed when there is high level of organic matter.

6.7. Causes of Zinc Deficiency at Adigudom and Dogua Tembien

Soil Catenas

Extractable Zn was deficient in all soil types of both sites and Cu deficiency was observed in

Cambisol at Adigudom and in the plant grown there. These were the soils at the slope telTain

SUbjected to intensive erosion and highly weathered soil. The relatively higher concentrations of

Ca, Mg, sand fraction, high CEC and pH are expected to contribute to Zn deficiency. Krauskopt

(1972) also reported that deficiency of Zn is most likely occurring on soils with high sand

48 fractions (sandy soils) formed from parent materials low in Zn. Murthy et.al. (1982), described that removal of surface soil by erosion, land leveling, and ten'acing are the management practices that can enhance Zn deficiency. Mortvedt and Gilkes (1993) explained that deficiencies of Zn are more wide spread than those of other micl'Onutrients and deficiencies occur in many soil types with pH levels> 6.0, especially low in organic matter.

This was also found to be true in Vertisols and Cambisols at all position in Adigudom and Dogua

Tembien where the average pH value was greater than 6.0.

49 7. Conclusion and Recommendation 7.1. Conclusion

The high pH of the soils at both Catenae largely contributed to micronutrient deficiency. The results obtained from both soil and plant analyses of this study showed that except DTPA extractable Zn all the rest are at sufficient levels which agree with the research studies repOlted by different authors (Desta Beyene, 1983; Pulschen, 1988; Fisseha Itanna, 1992). In general, the bioavailability of Fe, Cu, Mn and Zn increase with decreasing pH. Extractable Zn is negatively affected by pH, exchangeable bases (Ca and Mg), CEC and CaC03%, which are expected to be some of the factors responsible for its being deficient in the study areas. In general, all the extractable micronutrients in the catena are positively correlated to CEC, base saturation (except

Zn).

Of the exchangeable bases, Ca and Mg are the dominant cations occupying the exchange sites and are the major elements competing with the DTPA micronutrients. pH, %sand, %Clay, and %

CaC03 are the factors found to be highly responsible for the DTPA extractable Zn to be deficient in Adigudom and Dogua Tembien soil catenas. The result clearly indicated that micronutrients and other soil physical and chemical properties including soil types are highly dependent on the landscape position in a catena.

The result obtained from plant analysis has shown that there is marked difference of nutlient up take by barely crop. Fe, Mn and Zn are sufficient level with the exception of Zn which is deficient at Adigudom Cambisol. Cu concentration in barely leaf in both soil types was at deficient level.

In Dogua Tembien, the result obtained from soil analysis has shown that extractable Fe, Mn and

Cu are at sufficient level in both soil types . Where as extractable Zn is at deficient level. In

50 Adigudom, extractable Fe, Mn and Cu in Vettisol are at sufficient level with the exception of Zn in both areas and Cu in Adigudom Cambisols.

7.2. Recommendations

As agriculture becomes more advanced and intensive fatming systems develop, the deficiency of micronutrients will become more frequent and extensive. Therefore, farmers should apply organic manures to their fatms to improve the soil physical, chemical and biological propetties or sustained organic intensification efforts in crop production.

Since the different soil types at different positions are subjected to erosion problems due to unwise land use and wide spread forest clearance, an appropriate soil and water conservation mechanisms should be devised so as to conserve the nuttients.

To avoid the soil erosion in the catenas, land leveling, terracing, contour ploughing and ship cultivation should be continuously practiced and this could minimize nutrient loss. Use of crop rotations, organic fertilizers and use of crops tolerant to micronuttient deficiency can solve the problem. Application of micronuttient fertilizers particularly that could compensate the deficient

Zn that could increase food production.

Last but not the least, it would be wise to make a comprehensive study in to the status of micronuttients in vatious patts of the region to provide some basic information on the general status of micronutrients under different soil, climatic and cultural conditions. The result from the study will help to locate the problem areas, where specific micronuttients are likely to be deficient, more detailed research, and experimentation will be undertaken.

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Planning and Economic Development, Transitional Government of Ethiopia.

TFAP, Bureau of Agliculture and Natural Resource Development (1996). Tigray Forestry Action

Plan. Regional Govel1uuent of Tigray, Mekelle, Ethiopia.

Walkley, A. and Black, LA. (1984). An examination of the Degtfareff method for detelmining

soil organic matter and proposed modification of the chromic acid titration method. Soil

sci. 37: 29-38.

Warren, A. and Khogali, (1992). Assessment of Desertification and Drought in the Sudan­

Sahelian Region 1985-1991, UNSO, New York.

58 White, M.e., Decker, A.M. and Chaney, R.L. (1979). Differential Cultivars tolerance in

Soyabean to phytotoxic levels of soil zinc 1. Range of cultivars response. Agron . J. 71:

121-126.

Wildkinson, S.R., Grunes, D.L. and Sumner, M.E. (2000). Nutlient interactions in Soil and Plant

nutlition. In: Mineral nutrition of plants, Pp D-89-D-107, (Sumner, M.E., ed.) CRC Press,

New York.

59 9. Appendix

Profile Description

Profile No AG-I

Location Adigudom Kebele Farmer's Association (13° 14.83'N;

39032.029'E)

Date of description 8-11-2002

Landform almost plane

Land use cultivated wheat field

Elevation 2115 m.a.s.!

Moisture condition in the soil

Parent material Calcite

Depth of ground water not encountered

Surface features Rock out crops: 1-2%

Surface stone: few to many

Evidence of erosion Sheet erosion

Soil classification Local: Bahakal

FAO: Vertic Cambisols

60 Horizon description

AP

0·15 em Brown (10 YR 4/3) dry, dark -brown (7.5YR3/2) moist; slightly plastic; sandy

loam, medium prismatic (20-30mm) fliable; cracking (5 mm wide); fluquent root

distribution; with sUliace pores; less effervescence in Hel.

Bw1

15·30 em Dark-brown (1.5 YR 3/3) moist, brown (7.5 YR 4/4) dry; Blocky, Sandy loam

slightly plastic; hard, colluvial; rare roots; no nodules; craks (0.4-0.5mm); positive

effervescence to Hel.

BWz

30·65 em Brown (10 YR 4/3) moist, dark gray brown (10 YR 4/2) dry; slightly sticky; Very

hard, friable blocky; no crack; strong effervescence in Hel.

c

>95 em Unconsolidated matelial

Profile number AG-II

Location Adigudom Kebele Farmers' Association (l3014.620'N;

39032.26'E)

Date of descri ption 8-11-2002

Landform Slightly flat

Land use cultivated teff field

61 Elevation 2012 m.a.s.l

Moisture condition in the soil dry

Parent material basalt

Depth of ground water not encountered

Surface features Rock out crops: 1-2%

Sulface stones: few

Soil classification Local: Walka

FAO: Pellic Vertisol

Horizon description

Ap

0·25 em Very dark brown (7.5 YR 2.5/2) moist, dark gray (7.5 YR 4/1) dlY with about 1.5

cm porous material appended below; clay; strongly, coarse angular blocky

structure; slightly sticky, slightly plastic; hard; many fine (up to 2mm) roots;

abrupt smooth boundaty.

25·75 em Black (7.5 YR 2.5/1) moist, black (7.5 YR 2/1) diY, clay; strongly coarse blocky

structure; slightly sticky; slightly plastic; hard fine (up to 2mm) roots.

62 Bwz

75 -105 em Black (10 YR 2/1) moist, velY dark gray (10 YR r3/1) dlY; clay; strongly coarse

polygonal st11lcture; slightly sticky; slightly plastic; hard; few rock fragments;

very few fine (upt02mm) roots

C

>105 em Unconsolidated material

Profile number DT-I

Location Selam Kebele Falmers' Association (13 039'25.0"N;

39°12' 11.5"E)

Date of description 13-11-2002

Land form Undulating

Land use Culti vated Lentile

Moisture condition in the soil dry

Parent material Basaltic Colluvium over Silicfied limestone

Depth of the ground not encoun tered

SUiface features Rock out crops 1-2%

SUiface stone few -many

Evidence of erosion Rill erosion

Soil classification Local Bahakal

FAO Vertic Cambisol

63 Horizon Description

AP

0-9 emDark -brown (7.5YR 3/2) moist, very dark gray (10 YR311) dry; loamy gray; sub­ angular; slightly plastic; no pores; slight calcium carbonate, diffuse boundaty.

Bw

9-40 cm Very dark brown (10 YR 2/2) moist, very dark gray (10 YR 3/1) dty; slightly plastic; lOamy clay; moderate to strong, sub angular; few pores<1mm, moderate calcium carbonate; diffuse boundaty. c

>40 em hard rock

Profile number DT-II

Location Selam Kebele Patmers' Association (l3039'25.4"N; 39012'11.5"E)

Date of description 13-11-2002

Land form Gently Undulating

Land use Cultivated barely

Moisture Condition in the soil Dty

Parent Matetial Basaltic Colluvium Over Silicified limestone

64 Evidence of erosion Rill erosion

Soil classification local: Bahakal

FAO: Pellic VeIitsol

Horizon Description

Ap

O·lOcm Black (lOYR 2/1) moist, velY dark gray (7.5YR3/1) with about 1 cm porous

material appended below; sub-angular; friable, plastic; clear boundmy with few

pores (

Bwl

lO·65cm Black (lOYR2/1) moist, very dark gray (lOYR 31R) dlY; heavy clay; strong sub­

angular; friable; plastic, diffuse boundmy; with few pores

Bw2

65·140cm Black (lOYR2/1) moist; velY dark gray (lOYR 3/1) dlY; heavy clay wedge shaped

;velY hard; plastic wavy boundary; with few pores

>140cm Unconsolidated material

65 If!. If!. 0 "'-0 «J 0 E E E E Depth • If!. W OJ OJ Z :;; Q) c ~ 0. W

If!. "'-0 OJ & 0 E E E E Depth If!. W ~ ~ ~ c c ~ 0. W

If!. If!. q; If!. «J e;;- 0 E E E E Depth If!. W OJ z c ~ 0. W

"'-0 If!. 0 "'-0 OJ 0 E E E E Depth If!. W ~ OJ ~ Q) c ~ 0. W

Table A4: - Physical and chemical Soil Analysis of Adigudom (Cambisol) Means

Soil types of each reQion pH(H2O) EC Sand % SiI!% Clay % M.C.% Do.gua Tembien Vertisol ~.06 p.20 16.67 18.00 65.33 12.45 Dogua Temben Cambisol ~.20 p.26 ~O 22.00 58.00 ~.89 Adigudom Vertisol ~.53 p.13 ~.33 28.00 62.67 17.18 Adigudom Cambisol 8.65 0.09 ~.75 40.75 52.50 10.97 h'otal 8.40 0.15 12.08 28.75 59.17 ~.71

Table AS (a)

66 Soil types of each region Bulk Density Na K ra MQ CEC Doqua Tembien Vertisol 1.21 0.50 p.83 b6.74 15.14 h58.53 Dogua Temben Cambisol 1.12 0.48 0.90 ~3.56 10.50 ~2.00 !Adigudom Vertisol 1.52 1.13 p.80 ~2.50 8.01 k8.27 !Adigudom Cambisol 1.52 0.38 P.55 125.75 1.64 ~2.05 Table AS (b)

Soil types of each region Bas.Sa CaC03% T,N% O.C% CIN Av. % P.Olsen Dogua Tembien Vertisol 90.67 4.60 0.13 1.34 10.33 1.60 Dogua Tembien Cambisol 87.00 5.70 0.12 1.07 9.00 1.60 Adigudom Vertisol 88.00 1.20 0.09 0.85 10.67 3.40 Adiglldom Cambisol 87.75 17.10 0.12 0.99 8.00 0.87 Total 88.42 8.10 0.12 1.06 9.42 1.45 Table AS (e)

Soil types of each region O.M% Fe (ppm) Mn (ppm) Zn(ppm) Cu(ppm) Dogua Tembien Vertisol 2.31 9.44 7.10 0.07 2.53 Dogua Tembien Cambisol 1.84 10.51 13.48 0.16 0.07 Adiglldom Vertisol 1.47 13.13 7.73 0.17 1.92 Adigudom Cambisol l.71 6.19 7.22 0.17 0.47 Total 1.82 9.46 8.36 0.14 1.62 Table AS (d)

67 NPar Tests

Descriptive Statistics

Table A6. Kruskal-Wallis Test for soil physical and chemical property for profile pits of

Dogua Tembien and Adigudom.

N Mean Std. Deviation Minimum Maximum

PH 12 8.40 0.37 7.40 8.80 EC 12 0.15 0.12 0.02 0.37 Sand % 12 12.08 6.47 4.00 22.00 Silt % 12 28.75 11.24 14.00 51.00 Clay % 12 59.17 7.41 42.00 68.00 M.C% 12 9.71 4.41 2.54 17.92 Bulk Density 12 1.38 0.23 0.98 1.63 Na 12 0.62 0.39 0.33 1.65 K 12 0.74 0.28 0.27 1.19 Ca 12 31.49 5.62 19.36 39.07 Mg 12 8.08 5.76 1.23 19.75 CEC 12 46.05 11.32 28.20 60.40 Bas. Sa % 12 88.42 6.46 76.00 99.00 CaC03 % 12 8.10 7.45 0.90 21.90 T.N% 12 0.12 0.03 0.06 0.17 O.C% 12 1.06 0.30 0.46 1.54 C/N 12 9.42 2.19 7.00 13.00 AV.P 12 1.45 1.38 0.20 5.40 O.M% 12 1.82 0.52 0.80 2.65 Fe (ppm) 12 9.46 3.38 3.50 14.48 Mn (ppm) 12 8.36 3.80 2.66 17.86 Zn (ppm) 12 0.14 0.09 0.04 0.36 Cu (ppm) 12 1.62 0.92 0.10 2.64 Soil types of each region 12 2.67 1.23 1.00 4.00

68 Oneway

Table A 7: - Test of Homogeneity of Variance of soil Physical and Chemical propelty of profile

soil.

Leven Statistic df 1 df 2 Sig.

pH 5.16 3 8 0.03 EC 1.59 3 8 0.27 Sand 2.20 3 8 0.17 Silt % 15.67 3 8 0.00 Clay 9.98 3 8 0.00 M.C. 11.44 3 8 0.00 Bulk Density 0.14 3 8 0.94 Na 3.17 3 8 0.09 K 7.29 3 8 0.01 Ca 4.44 3 8 0.04 Mg 7.80 3 8 0.01 CEC 0.89 3 8 0.49 Bas. Sa 2.67 3 8 0.12 CaC03 16.17 3 8 0.00 T.N 1.62 3 8 0.26 O.C 7.95 3 8 0.01 C/N 1.82 3 8 0.22 AV-P.O 54.14 3 8 0.00 O,M 7.97 3 8 0.01 Fe (ppm) 5.50 3 8 0.02 Mn (ppm) 5.56 3 8 0.02 Zn (ppm) 2.63 3 8 0.12 Cu (ppm) 3.40 3 8 0.07

69 Table AS: - Spemman's Rho (Nonparametric) Con'elations between soil parameter.

pH EC Sand % Silt % Clay % M.C% Bulk density pH 1.00 -.19 -.84** 0.77** -.25 -.00 0.90'* EC -.19 1.00 0.09 -.20 0.08 -.19 -.24 Sand % -.84" 0.09 1.00 -.78** 0.09 0.24 -.83** Silt % .77** -.20 -.78** I -.63* -.17 0.69* Clay % -.25 .08 0.09 -.63* I 0.10 -.12 M.C% -.00 -.19 0.24 -.17 0.10 I -.06 Bulk density .90 -.24 -.83** 0.69 -.12 -.06 I Na .24 0.30 -.20 -.11 0.45 -.07 0.38 K -.6\* -.15 0.37 -.32 0.26 -.27 -.58* C. -.84** 0.19 0.74** -.88** 0.56 -.10 -.70* Mg -.67* 0.38 0.62* -.89** 0.71 ** 0.14 -.60' CEC -.74** 0.36 0.62 -.91** 0.70' 0.06 -.64* Bas.sa% -.55 -.05 0.25 -.22 0.25 0.06 -.50 CaC03 % .40 -.16 -.23 0.47 -.58 0.25 0.17 T.N% -.20 -.14 .14 -.28 0.26 0.09 -.45 O.C% -.61 * -.01 .46 -.52 0.39 0.21 -.73** CIN -.66* 0.20 .50 -.50 0.37 -.03 -.47 AV.P.OL -.87** 0.18 .74** -.58* 0.11 -.04 -.96** O.M% -.61 * -.01 .46 -.52 0.39 0.21 -.73** Fe (ppm) -.25 0.20 .14 -.37 0.56 -.46 -.11 Mn (ppm) -.53 -.05 .29 -.16 0.03 -.26 -.60' Zn (ppm) -.03 0.31 -.24 .32 -.08 -.55 -.04 Cu (ppm) -.63 0.31 .63 -.90** 0.64* 0.24 -.60*

70 Spearman's rho continued , .. Na K Ca Mg CEC Bas. Sa % CaC03 % PH 0.24 -.61' -.84*' -.67* ~.74** -.55 0.40 EC 0.30 -.15 0.19 0.38 0.36 -.05 -.16 Sand % -.20 0.37 0.74" 0.62' 0.62' 0.25 -.23 Silt % -.11 -.32 -.88** -.90** -.91 ** -.22 0.47 Clay % 0.45 0.26 0.56 0.71*' 0.70* 0.25 -.58 M.C% -.07 -.27 -.09 0.14 0.06 0.06 0.25 Bulk density .38 -58* -.70* -.60' -.64 -.50 0.17 Na I -.08 0.08 0.29 0.21 -.29 -.70' K -.08 I 0.52 0.28 0.34 0.58' -.58 Ca -.08 0.52 I 0.85** 0.88" 0.46 -.58 Mg 0.29 0.28 0.85" I 0.97** 0.25 -.51 CEC 0.21 0.34 0.88** I I 0.28 -.52 Bas.sa% -.29 0.58* 0.46 0.25*' 0.28 I -.22 CaC03 % -.70' -.58 -.58 -.51 -.52 -.22 I T.N% -.47 0.18 0.15 0.18 0.20 0.43 0.27 O.C% -.53 0.50 0.51 0.44 0.47 0.71* 0.05 CIN 0.00 0.62* 0.61' 0.38 0.42 0.46 -.54 AV.P.OL -,45 0.66 0.64* 0.51 0.56 0.60' -.14 O.M% -.53 0.50 0.51 0.44 0,47 0.71' 0.05 Fe (ppm) 0.61* 0.57 0.48 0.37 0.36 0.15 -.87** Mn (ppm) -.18 0.74** 0.29 0.17 0.21 0.62' -.32 Zn (ppm) 0.12 0,45 -.08 -.21 -.21 0.43 -.30 Cu (Dpm) 0.28 0.27 0.78'* 1,0** 0.94*' 0.10 -,49

T.N% O.C% CIN AVP.OL O.M% Fe Muppm Zn Cuppm DPm ppm pH -.20 -.61* -.66* -.87** -.61' -.25 -.53 -.03 -.63* EC -.14 -.01 0.20 0.18 -.01 0.20 -.05 0.31 0.31 Sand % 0.14 0,46 0.50 0.74" 0,46 0.14 0.29 -.24 0.63' Silt % -.28 -.52 -.50 -.58* 0.52 -.37 -.16 0.32 -.90** Clay % 0.26 0.39 0.57 0.11 0.39 0.56 0.03 -.08 0.64* M.C% 0.9 0.21 -.03 -.04 0.21 -.46 -.26 -.55 0.24 Bulk density -,45 -.73** -.47 -.96** -.73** -.11 -.59* -.04 -.60' Na -,47 -.53 0.00 -.45 -.53 0.61* -.18 0.12 0.28 K 0.18 0.50 0.62' 0.66' 0.50 0.57 0.74" 0.45 0.27 Ca 0.15 0.51 0.61' 0.64' 0.51 0.48 0.29 0.08 0.78** Mg 0.18 0.44 0.38 0.51 0.44 0.37 0.18 -.21 0.94** ~ CEC 0.20 0.47 0.42 0.56 0.47 0.36 0.21 -.21 0.94** Bas.sa% 0.43 0.71* 0.46 0.60* 0.71* 0.15 0.62' 0.43 0.10 CaC03 % 0.27 0.05 -.54 -.14 0.05 -.87** -.32 -.30 -.49 T.N% I 0.75*' -.13 0.52 0.75*' -.10 0.44 0.04 0.15 O.C% 0.75** I 0.46 0.79*' I" 0.05 0.45 0.08 0.37 CIN -.13 0.46 I 0.47 0.46 0.55 0.17 0.24 0.34 AV.P.OL 0.52 0.79*' 0.47 I 0.79** 0.14 0.73** 0.21 0.45 O.M% 0.75** I" 0.46 0.79** I 0.05 0.45 0.08 0.37 Fe (ppm) -.10 0.05 0.55 0.14 0.05 I 0.30 0.49 0.30 Mil (ppm) 0.44 0.45 0.17 0.73*' 0.45 0.30 I 0.59' 0.08 Zn (ppm) 0.04 0.08 0.24 0.21 0.08 0.49 0.59 I -.38 Cu fI>IJIn) 0.15 0.37.. 0.34 0.45 0.37 0.30 0.08 -.38 I **. Correlation IS slgnilicant at the 0.01 level (2 - tailed), *, Correlation is significant at the 0.05 level (2- tailed),

71 T-Test

Group Statistics

N Mean Std. Deviation Std. Error Mean Plant micronutrients Plant micronutrients Plant micronutrients Plant micro nutrients versus surface soil versus surface soil versus surface soil versus surface soil micronutrient micronutrient micronutrient micronutrient Plant Soil Plant Soil Plant Soil Plant Soil

Fe (ppm) 4 4 164.92 12.59 15.47 3.14 7.73 1.57 Mn ppm) 4 4 68.50 9.49 9.07 2.36 4.53 1.18 Zn (ppm) 4 4 27.58 0.35 4.09 0.21 2.05 0.10 Cu (ppm) 4 4 3.58 2.39 0.32 0.93 0.16 0.46

Table A9- Plant micronutrient versus soil micronutrient.

Region and soil names Fe (ppm) Mn (ppm) Zn (ppm) eu (ppm) Dogua Tembien Vertisol 179.67 55.33 33.33 3.33 Dogua Tembien Cambisol 154.00 74.67 23.67 3.33 Adigudom Vertisol 176.67 69.67 26.33 3.67 Adigudom Cambisol 149.33 74.33 27.00 4.00 Total 164.92 68.50 27.58 3.58

Table A 10: - Mean of Plant Extractable Micronutrients

72 Table: - All-. Broad rating of soil parameters

A. Organic Carbon Content Walkley- Black method Rating (% of soil by weight >20 VelY high 10-20 High 4-10 Medium 2-4 Low <2 VelY low

B. Total Nitrogen (TN), Kjeldhal Method (%of soil by weight

>l.0 VelY high 0.5-l.0 High 0.2-0.5 Medium 0.1-0.2 Low

C. pH 1:2.5 Soil: Watel' Suspension

>8.5 Very high 7.0-8.5 High 5.5-7.0 Medium <5.5 Low

D. Exchangeable Bases (Meq/l00g Soil

Ca >10 High <4 Low Mg >4.0 High <0.5 Low K >0.6 High Na >l.0 High E. Cat ion Exchange Capacity (Meq/l00g Soil)

>40 Very high 25-40 High 15-25 Medium 5-15 Low <5 Very low

73 F. Availa ble P (ppm) Olsen Method

<5 Low 5-15 Medium >15 High

G. DTPA Extractable Soil Micronlltrients (deficiency levels) ppm

Cu 0.75 Fe 2.5 - 4.5 Mn 5-9 Zn 0.5 - 1

H. Organic MaUer Content by%

>6.0 VelY high 4.3-6.0 High 2.1-4.2 Medium 1.0-2.0 Low <1.0 VelY!ow

Source: Collected from MAFF (1967), Metson (1961) Cox and Kamprath (1972), Olsen and Dean (1965).

Table A12: - Indicative ratings for foliar analysis of micronut1'ients in ppm

Micronutlient Deficiency Sufficiency Excessive/ toxic

Cu <4 5-15 >20 Fe <50 50-250 ? Mn <20 20-500 >500 Zn <20 25-150 >400

Source: Jones, 1972.

74 ~ s p. s p.s s s 0'" p. p. p. p. p. u ~ ~ p. p. p. p. oj Z u :::> ~ U f-< 0 B ~ & ~ ~ u Dogua Tembien Carnbisol 8.2 3.8 1.2 2.09 11 9.8 11.32 9.46 0.66 2.54 Dogua Tembien Vertisol 8.4 3.7 0.12 1.3 10 3.4 10.96 8.7 0.26 2.52 Adigudorn Carnbisol 8.4 8.9 0.14 1.4 10 2.4 10.78 12.7 0.24 1.44 Adigudom Vertisol 8.3 1.1 0.08 0.86 11 1.2 17.28 7.1 0.24 1.98

Fig A 13: -Result sheet for sUiface soils analysis (Dogua Tembien and Adigudom).

75