Council for Scientific and Industrial Research Soil

COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH

SOIL RESEARCH INSTITUTE

REPORT ON THE SOIL RESOURCES OF TAIN DISTRICT,

BRONG AHAFO REGION, GHANA

(CSIR / WAAPP NO. 017)

Project Team: James Kofi Senayah (Leader), K. Abrefa Nketia, Emmanuel Amoakwa, Johnny Awoonor, Anim Boafo,

Kwadaso, Kumasi

May, 2013

1.0 INTRODUCTION

1.1 Background Information

Soil information is basic to several economic sectors such as farming, establishment of pastures, forestry, construction of fish pond, mining activities, etc.

Soil maps provide a quick summary of soil information that assists in determining the suitability or potential of an area for any agricultural and other related land-use. They are guides to investors and planning tools for agricultural planners.

The work on the Tain District in the Brong Ahafo Region, seeks to provide a more detailed soil and related information that will provide relevant information as input in the preparation of any development plan for the district and also provide quick information on potential agricultural and other landuse areas.

Tain District occurs within the Tain River Basin Soil Survey Region of the CSIR-Soil Research Institute. It is a recently created district that requires knowledge on its natural resources to assist in its quest for development and a boost in economic activities. The District is basically agriculturally oriented but has little information on its soil resources due to its remoteness until the recent construction of the Bui dam.

Basic soil information which provided the baseline data for this study is the draft report of the detailed reconnaissance soil survey of the Tain River Basin and a soil map (1997) available at the CSIR-Soil Research Institute.

1.2 Location and extent

The Tain District occurs within the Tain Basin soil survey region of the CSIR-Soil Research Institute. The Bui dam is found in the district. The administrative capital is Nsawkaw. Other major towns are Badu, Seikwa, Menji, Sabiyi, Banda Ahenkro.

Tain District is located in the Brong Ahafo Region. It is bounded in the north by the Bole District with the Black Volta separating them, in the east by Wenchi Municipality, in the west by Cote d’Ivoire and the Jaman North District and in the south by Berekum and Sunyani Municipality. It covers an area of about …….sq km.

Map 1. Location of Tain district

1.3 Objectives

The objectives of this work are to:

 describe the morphological characteristics of the soils within the municipality

 map the distribution of the soils

 evaluate the soils for the production of major crops in the District

 recommend fertility improvement measures for the production of major crops in the District

1.4 Method of study

Basic soil information was compiled from the draft report of the Tain River Basin (CSIR-Soil Research Institute, undated) and the soil map (SRI, 1997).

A digitized base map of the district was prepared with the following overlays: soil map on a scale of 1:250,000, contours from the Survey Department of Ghana, rivers and streams, roads and settlements. Several transects were selected on each soil unit for soil and land use observation and recording. Soil observation was carried out along each transect to ensure that the various soils along the catena or the slope were captured. In the field, the co-ordinates of each observed point was recorded by means of Global Positioning System (GPS). Profile pits were dug, described and sampled for laboratory analyses.

The observed points were plotted on the base map in the Arc-GIS software.

2.0 PHYSICAL ENVIRONMENTAL CONDITIONS

2.1 Climate

There are two rainy and two dry seasons. The southern part receives an average annual rainfall of 55”(1397 mm) and the northern part about 45” (1143 mm) (Asare, 1961). This is to indicate that the district falls within two climatic zones namely the moist semi-deciduous forest to the south around Seikwa and the Guinea savanna to the north. The rainfall pattern appears to be similar with major rainy season from April to mid July and minor rainy season from mid August to October. The main dry season is from November to March while the minor is mid July to August. The south is differentiated from the north by the amount of rainfall and humidity which is higher in the former.

2.2 Vegetation and land use

The northern part of the district supports Guinea Savanna Woodland and the southern part, Mixed Derived Savanna – Forest Vegetation (Asare, 1961). The former consists mainly of mixed tall and high tufted grasses, with frequent trees usually below a girth of 30”. The dominant grasses are Hyparrhenia sp., Andropogon gayanus and in frequently cultivated areas, Imperata cylindrical. The common trees are Terminalia sokodense, Lophira lanceolata, and Hymenocardia acida.

In the Derived Savanna, Andropogon tectorum and Sarcocephalus esculentus are common. The river valleys sometimes support fringing thicket and there is a fringing forest along the large streams and rivers.

2.3 Releief and drainage

The topography is gently undulating in the savanna area and gently undulating to gently rolling in the Derived Savanna area. The western half is dominated hill ranges and the eastern part by dissected plateau

2.4 Geology

The area is underlain by Upper and Lower Birimian (mid-Pre-Cambrian), Tarkwaian (Upper Pre- Cambrian) formations (Asare, 1961). The Birimian is intruded locally by granites. The Birimian is made up mainly of greenstones and schist with quartz veins; the Tarkwaian of conglomeratic schists and quartzites.

3.0 THE SOILS OF THE AREA

3.1 Introduction

The soils are developed under the Moist Semi-Deciduous Forest in the south and the Guinea Savanna to the north. The soils in the south are developed over the Lower Birimian phyllite which belongs to the Bekwai – Oda Compound Association.

The soils in the Savanna occur on fairly well drained summits, upper and middle slopes. They are reddish brown to brown in colour. They are of three (3) kinds (Asare, 1961).

1. Shallow iron pan soils

2. Gravelly soils

3. Deep, non-gravelly soils

Generally, the soils of the Tain District are grouped into the following soil associations (Map 2),

1. Sampa Association

2. Banda Association

3. Debibi Association

4. Drobo Association

5. Foamang Association

6. Bekwai – Oda Compound Association

7. Dumboli Association

Each soil association has a combination of the three kinds of soils indicated above but in varying proportions.

3.2 Description of the soils

1. SAMPA ASSOCIATION

The area is underlain mainly by phyllites with quartz veins. Two terrain units were identified within this soil association. . They are

1. The generally undulating topography with slopes generally between 2 – 8%

2. The moderately steep rolling topography with slopes between 8 and 16%.

Soils of the Sampa association are summarized in a table in the appendix. The summary is adapted from the draft report on ‘Soils of the Tain River Basin’. The soils described occur over both category of topography. They are grouped as Upland and Lowland soils

UPLAND SOILS

Peneplain drift soils

Soils encountered on the summits and upper slopes are Duadaso series.

Duadaso series (Haplic Lixisol)

The soil is deep (140 cm), well drained and non-gravelly occurring on summits and upper slopes. The profile consists of brownish grey to grayish brown sandy loam topsoil of about 15 cm thick. The underlying subsoil is light yellowish brown, sandy clay loam to sandy clay to a depth of about 140 cm where incipient iron pan may be encountered. A shallow profile with ironpan at 82 cm was encountered.

Concretionary soils

Morle series (Pinthosol)

Morle series is a gravelly, moderately shallow soil occurring on upper slopes. The topsoil is 0 – 17 cm dark grey silt loam with very few ironstone concretions. The underlying subsoil up to about 60 cm is brown to yellowish brown clay containing abundant small and large irregular ironstone concretions. Ironpan is encountered at 60 cm.

Wenchi series (Plinthic Leptosol)

Wenchi series is a shallow ironpan soil occurring on summits and upper slopes. It consists of 0 – 30 cm of gravelly topsoil overlying a thick sheet ironpan. Where erosion is severe, the sheet ironpan is exposed on the surface. This soil only occurs in small patches. It is unsuitable for cultivation.

Sampa series (Plinthosol)

Sampa series is a deep (>120 cm), well drained, concretionary soil found on upper slopes. The profile consists of a silty clay loam topsoil, about 10 cm thick, which is underlain by strong brown to yellowish red silty clay loam, containing many to abundant ironstone concretions and quartz gravel to depths of over 110 cm.

Nsawkaw series

Nsawkaw series is a soil containing abundant quartz gravel. It normally occurs on middle slopes. The topsoil consists of silty clay with very few fine quartz gravel. The underlying subsoil is clay which contains abundant fine and coarse quartz gravel. The quartz increases from few to abundant down the profile with few ironstone concretions.

Sedentary and gravelly soils

Drobo series

Drobo series is deep, well drained, gravelly soil found on upper slopes. The topsoil consists of 15 cm thick of dark brown silty clay loam with few quartz gravel and ironstone concretions. The underlying subsoil is reddish brown silty clay loam with many to abundant quartz gravel and few ironstone concretions to about 80 cm. From 80 cm downwards, the quartz gravel is significantly reduced to few with traces or patches of decomposed rock to 120 cm depth.

Debibi

Debibi series is the brown drainage associate of Drobo series. It normally occurs on middle slopes. Like Drobo series, Debibi consists of about 120 cm of gravel, mainly quartz which merges into decomposing phyllite. The profile consists of brown, silty clay loam with few quartz gravel and iron concretions in the top 0 – 15 cm. The underlying subsoil is reddish yellow silty clay loam which contains many to abundant quartz gravel with few ironstone concretions to a depth of 110 cm.

Kasampiri series (Leptosol)

Kasampiri series is a shallow skeletal soil that occurs on moderately steep slopes, usually over 10%. The soil consists of about 45 – 60 cm of partially decomposed rock which grades into bedrock.

Amonfonso (Gleyic Lixisol)

Amanfonso series is a yellowish brown soil occurring on middle to lower slopes or foot of hills. It is deep, moderate to imperfectly drained. The profile consists of grayish brown, fine sandy loam or silt loam topsoil, which overlies light yellowish brown silty clay. Common ironstone concretions occur from the depth of 65 cm to over 120 cm

LOWLAND ASSOCIATION

Colluvial soils

Kresua series (Gleyic Lixisol)

Kresua series is a deep, moderate to imperfectly drained soil occurring on middle to lower slopes. The topsoil is grayish brown silty clay. Mottles occur from 60 cm downwards. A stoneline occurs deep in the profile.

Buni

Buni series occurs on lower slope and it is characterized by about 40 – 50 cm of silty or sandy clay loam overlying a concretionary layer which in turn is underlain by decomposing rock

Goka

Goka series is a concretionary lower slope soil occurring in small patches. It has a silty light clay texture. It is light grey in colour and consists of 120-150 cm of small rounded, polished ironstone concretions overlying decomposing rock.

Alluvial soils

Mampa series ( Haplic Gleysol)

Mampa series is a poorly drained grey alluvial bottom soil. It is deep and consists of about 150 cm or more clay throughout its profile, which cracks when dry.

Chichiwere series (Fluvisol)

Chichewere series is a pale brown alluvial soil occurring in narrow bands on raised banks of streams and rivers. It has a loamy sand texture.

2. BANDA ASSOCIATION

The Banda soil association divided into three sub-units as follows,

i. gentle undulating terrain which consists dominantly of deep, gravel-free soils on summits, upper and middle slopes (Bofe and Bau series) with few occurrences of concretionary and iron pan soils. These soils mainly occur from Bofe to Bui.

ii. Areas dominated by deep to moderately deep soils containing abundant ironstone concretions with patches of shallow ironpan soils, boulders and outcrops (Banda, Bungase, Meinji, Wenchi and Morle series) (Soil unit 2B)

iii. Banda hill consociation, consisting of steep hill ranges with mainly rock outcrops, boulders and shallow soils (Lanka series) (Soil unit 2C)

Peneplain drift

Bofe series (Haplic Lixisol) Bofe series is a deep, reddish brown, non-gravelly soil that occurs on summits of undulating topography. The topsoil consists of sandy loam and the underlying subsoil is reddish brown sandy clay loam. Plinthite may develop deep in the profile which has the tendency of hardening into iron pan.

Bau series (Haplic Lixisol) Bau series is brown associate of Bofe series which occurs on upper slopes. It is deep, moderately well drained and non-gravelly. It also consists of sandy loam topsoil overlying sandy clay loam subsoil.

Concretionary soils assoc with peneplain drift (Banda, Bungase, Menji, Wenchi, Morle)

Banda series (Plinthosol) Banda series is a gravelly soil occurring on gently undulating topography on upper slopes of 2 – 5%. It has loamy fine sand topsoil which overlies sandy loam to sandy clay loam subsoil. The subsoil contains abundant ironstone concretions and quartz gravel (50 – 70% by volume) to depth of over 120cm. This soil occurs in patches.

Menji series (Plinthosol) Menji series is a brown concretionary drift found on middle slopes. It consists of about 183 cm of sandy clay loam with abundant manganese dioxide and ironstone concretions overlying weathering quartzite. It occurs in small patches and inextensive

Wenchi series

Sedentary

Kanka series This is a shallow brashy soil that occurs on upper slopes and summits of steep sided hills. The soil consists of about 100 – 150 cm of sandy loam with abundant pieces of weathering quartzites or schist overlying wearthering rock. It is normally associated with piedmont soils like Lura and Farming series.

Lura series (Haplic Lixisol) Lura series is a deep, non-concretionary, reddish brown soil that occurs at the foot of the Tarkwaian hills. It consists of about 180 cm of sandy clay loam. Lura series is associated with Farming and Kanka series. Lura is differentiated from Bofe and Bau series by occurring at the foot of steep rocky hills.

Farming series Farming series is a brown drainage associate of Lura series. It consists of about 180 cm sandy clay loam containing very few gravel or small pan boulders. It occurs on middle and upper slopes. It has good rooting properties.

LOWLAND Colluvial drift soils

Gradau series Gradau series is a pale brown sandy soil developed in hillwash material deposited in lower slopes. It consists of about 180 cm of pale brown non-gravelly loamy sand to sandy clay loam underlain by weathered quartzite or seepage ironpan. Gradau series is associated with Banda, Ngre, Bau, Brawhani and Sase series.

Sase series Sase series is a colluvial drift soil, occurring on lower slopes of gently undulating topography. It consists of about 80 cm of grey or pale brown sandy loam, containing manganese dioxide and ironstone concretions and pieces of ironpan.

Ngre series Ngre series is a shallow colluvial drift occurring on lower slopes. This grey soil consists of about 46 – 76 cm of loamy sand with ironstone concretions, overlying ironpan.

Alluvial drift soils Landa series (Fluvisol) Landa series is loose sand, grey to very pale brown in colour, occurring on lower slopes and bottoms. It consists of 120 – 150 cm of loose sand underlain by a strongly mottled loamy sand that is slightly firm. The soil has low water-holding capacity and is waterlogged during the main wet season.

Mua series Mua series is an alluvial soil that occurs on lower slopes and bottoms. It is characterized by 150 cm of grey sandy loam to sandy clay loam that is strongly to moderately mottled at relatively shallow depth. There is a subseries that may contain abundant ironstone concretions encountered at depth between 46cm and 92 cm. The soil is droughty during the latter part of the long dry season.

Lapla series (Gleysol) Lapla series is an alluvial soil occurring along streams and rivers. It consists of about 18 cm of sandy clay loam with strong mottling. It is associated with Mua, Sase and Landa series. A shallow subseries which consists of small rounded concretions at depth of 50 – 76 cm may be encountered.

3. DEBIBI ASSOCIATION

Topography is generally undulating. It consists of a. Deep, well drained sandy loam to sandy clay loam with gravelly subsoil on summits and upper slopes Deep, moderately well drained, gravelly or gravel-free sandy clay loams found on middle slopes Deep, imperfectly drained gravel-free sandy loams and sandy clay loams occupying the lower slopes and poorly drained alluvial clays in the valleys. b. Areas within the Debibi Association dominated by soils containing abundant ironstone Concretions and quartz gravel. Soils shallow to ironpan are also common.

This soil association occurs in the central part of the Tain District, stretching from Tainso and Badu through Nsawkaw towards Seikwa. The underlying geology is mainly phyllite with quartz veins. The soils are developed over gentle undulating topography. The base information from the draft report of the Tain River Basin, presents 23 soil series under this association. The numerous soil series is due to the forest and savanna conditions under which the parent material was weathered. Some of the soils developed under forest ecology have their equivalent also developed under savanna conditions with different names. The Debibi Association therefore, is a mixture of soils developed dominantly under savanna and few under forest particularly towards the south. During the investigation, two sub-units were observed and delineated. They are,

1. the deep soils with few to moderate amount of quartz gravel and ironstone concretions and

2. Soils dominantly gravelly and skeletal with quartz and ironstone concretions.

A brief description of all the soils of Debibi Association as presented in the draft report on the soils of the Tain River Basin is in the appendix. However, the soils encountered during the investigation are described as follows:

Areas under category 1 soils – Deep soils with few to moderate amount of gravel and concretions

On the upland, the summits and upper slopes are normally occupied by deep, well drained, non-gravelly sandy clay loam, Duadaso series or gravelly Drobo series. Also associated with these soils are concretionary and ironpan soils, Wenchi and Morle series.

Duadaso series

Duadaso series is deep, well drained, non-gravelly soil occurring on flat summits. The profile consists of brownish grey to grayish brown sandy loam topsoil of about 15 cm thick. The underlying subsoil is light yellowish brown, sandy clay loam to sandy clay to a depth of about 140 cm where incipient iron pan may be encountered. A shallow phase with underlying ironpan at 45 – 75 cm may be encountered. This is Buku sub series. Duadaso series is associated with gravelly and ironpan soils like Wenchi and Morle series.

Drobo series

Morle series

Wenchi series

Debibi series

Kasampiri series

Kasampiri series is a shallow skeletal soil that occurs on moderately steep slopes, usually over 10%. The soil consists of about 45 – 60 cm of partially decomposed rock which grades into bedrock.

Amanfonso series Amanfonso series is a yellowish brown soil occurring on middle to lower slopes or foot of hills. It is deep, moderate to imperfectly drained. The profile consists of grayish brown, fine sandy loam or silt loam topsoil, which overlies light yellowish brown silty clay. Common ironstone concretions occur from the depth of 65 cm to over 120 cm.

THE LOWLAND SOILS

Kresua series

Mampa series

Mampa series is a poorly drained grey bottom soil. It is deep and consists of about 150 cm or more clay throughout its profile, which cracks when dry.

Agricultural Potential of Debibi Association

The Debibi Association occurs over gentle undulating topography. The upland soils are generally deep, well drained sandy clay loams with subsoil gravels occurring from about 30 cm. They are moderately suitable for a range of climatically suitable crops such as maize, cassava and cashew. The valleys are deep, poorly drained, sandy loams and loamy sands which can be cultivated to rice and vegetables if flooding and poor drainage can be controlled during the rainy season.

Areas under category 2 soils – Abundant to dominant gravelly (skeletal) soils

These are areas within the Debibi Association dominated by soils containing abundant ironstone concretions and quartz gravel. Soils shallow to ironpan are also common. Commonly found soil series are …………………………………………………………..

4. DROBO ASSOCIATION

Topography is generally undulating. The soils are developed under both forest and savanna conditions. Soils consist of deep, sandy loam to sandy clay loam with gravel occurring deep in the subsoil on summit and upper slopes; deep and shallow concretionary soils on upper and middle slopes; deep sandy clay loams on middle slopes; deep colluvial silty clay loam on middle to lower slopes and poorly drained alluvial clays in valley bottoms

5. FOAMANG CONSOCIATION Enlongated hills of Upper Birimian rocks comprising mainly greenstones. The unit consists of shallow and skeletal soils. Deep piedmont soils may occur at the foot of the hills.

6. BEKWAI – ODA COMPOUND ASSOCIATION

Bekwai – Oda Compound Association is developed over the Lower Birimian phyllites. It occurs over gentle to undulating topography under forest.

In a catenary arrangement the soils consist of red, gravelly silty clay, Bekwai series on summits; a paler version of Bekwai series with a higher content of quartz gravels, Nzima series, occurs on upper and middle slopes but sometimes extends to the summit. It is the predominant soil in the association. The lower slopes are occupied by deep moderately well to imperfectly drained, non-gravelly yellowish brown silty clay loam to silty clays, Kokofu series. The valleys are occupied by poorly drained light grey sandy clay, Oda series or sand Temang series. Patches of shallow iron pan soils occur on summits and upper slopes particularly at the settlements where degradation is severe.

Bekwai – Nzima series (WRB, 2006: Cutanic Lixisol (Ferric))

The soils of this unit are developed over Lower Birimian phyllite. Bekwai series is red, well drained sedentary soil found on summit and upper slopes where slope gradients lie between 3 – 12%. Nzima series is the dominant soil in this soil association (Figure 12). It is the less well drained middle and upper slope associate of Bekwai series. Sometimes it replaces Bekwai series at the summit.

The soils are deep (>120 cm) and have silty loam topsoil. The underlying subsoil is silty clay loam to silty clay and contains many quartz gravel, stones and ironstone concretions. Both Bekwai and Nzima series have satisfactory rooting depth and good drainage conditions for crop development. However, their physical limitation is the appreciable amount of gravel in the subsoil. This limits the amount of potential moisture and nutrients the soil can hold. However, the medium to heavy textures possessed by the soils is able to hold adequate amount of water for a reasonable period of time. The soils are suitable for cultivation of a wide range of arable and tree crops such as cocoa, coffee, citrus, oil palm, avocado pear, mangoes, maize, cassava, yams, cocoyam, plantain, banana, pawpaw, pineapples and all kinds of vegetables.

Figure 1: Soil profile of Nzima series

Kokofu series (WRB, 2006: Haplic or Gleyic Lixisol)

Kokofu series, normally, is non-gravelly colluvial soils occupying lower slopes of 2-4% in the Bekwai – Oda soil catena. The soil is deep (>120cm) and moderately well or imperfectly drained. It is normally free of gravel but sometimes a gravel layer or stone-line may occur deep in the profile at about 80cm. Textures range from sandy loam to silt loam in the topsoil to sandy clay loam, clay loam and silty clay loam in the subsoil (Figure 13). The soil is easy to work, has good water-holding capacity and adequate depth for root development. Due to its lower slope position, it is able to store moisture much longer than Bekwai and Nzima series, which are located upslope. It is suitable for all crops mentioned under Bekwai and Nzima series.

Figure 2: Soil profile of Kokofu series

Oda and Temang series (WRB, 2006: Haplic Gleysol (Eutric))

These soils are found in the valley bottoms. They are deep and poorly drained. Oda series consist of clay loam and clay while Temang series is sand and loamy sand. They occur together in the valley and could not be mapped separately.

Oda soils are poorly drained and so are subject to water-logging during the rainy seasons. They have high water holding capacity due to their high clay content (over 30%). They therefore remain wet during the dry season. Temang series is also poorly drained but dries out quicker during the dry season due to the sandy texture.

These soils are suitable for rice and vegetable farming. However, drainage structures are required during the rainy season to drain off excess water. In the dry season, supplementary irrigation may be required for crop production.

Agricultural Potential of Bekwai – Oda Compound Association

The upland soils (Bekwai and Nzima series) are deep, well drained, silty clay with gravelly subsoil. They are moderately suitable for a wide range of arable and tree crops such as maize, plantain, cassava, cocoa, citrus, …. The limitation of these soils is the gravelly subsoil which are in moderate amount with no severe consequences on crop development. The lower slope, Kokofu series is deep, imperfectly drained, gravel-free, clay loam. It is a highly suitable soil for a wide range of crops grown on Bekwai and Nzima series upslope. The valley-bottom (Oda and Temang series) is poorly drained. If drainage is well managed, the soil is highly suitable for rice production.

KOBEDA – BEKWAI ASSOCIATION

This soil association occurs on steep inselbergs with slopes lying between 16-60% or more. The summits and the steep slopes are normally occupied by very shallow or rocky soils, Kobeda series or moderately deep, well drained, soft, deeply weathered phyllite soils, Amuni series. Moderately steep upper slopes within the hill have red, well drained gravelly / concretionary silty clay loam, Bekwai series.

Kobeda series (Leptosol) are well drained, brashy, shallow immature soils developed over little weathered phyllite. Generally they occupy summits and very steep upper slopes (25-40%). Occasionally, they are found on middle slopes. Rock outcrops are commonly associated with this soil.

Amuni series (Haplic Lixisol) is well drained. The profile consists of about 15 cm dark brown silty clay loam topsoil, which is underlain by 45 – 60 cm of reddish brown, silty clay loam to clay subsoil that may contain few fragments of rock brash. Underlying this subsoil is a soft, deeply weathered phyllite.

The Kobeda-Bekwai Association is generally limited by the very steep slopes and the commonly occurring shallow soils.

Agricultural Potential of Kobeda - Bekwai Association

This soil unit consists of a mixture of both shallow and deep soils. The severest limitation is the hilly nature with very steep slopes of over 25%. It is better left under vegetation cover to conserve biodiversity and prevent erosion.

7. DUMBOLI ASSOCIATION

This soil unit is developed over granite. It consists of: Imperfect to poorly drained loamy sands shallow to underlying ironpan between 45 and 60 cm depth on lower slopes; deep, alluvial clay in valley bottoms

Deep, highly gravelly , reddish brown sandy clay loam on middle to upper slope; light grey loamy sands overlying ironpan at more than 100 cm depth on upper slopes

3.3 Challenges of the study The only baseline work used for the study was the draft report on the “Soil Survey of the Tain River Basin”. The individual soils within one soil association unit were numerous. Debibi Association for example had as many as 23 individual soils (soil series) which were difficult to differentiate in some cases. Moreover, the duration of fieldwork planned for, was not adequate for a more detailed work. It is hoped that, subsequent works will build upon the original baseline data and this current one.

Map 2. Distribution of the soils

3.4 Soil suitability groupings

Most of the soil association units have profile characteristics that are similar and therefore have the same limitations and management practices. These soils have been grouped together in one suitability class. Their general description and limitations are given in Table 1 below (Map 3)

Table 1. Suitability grouping of the soil associations

Suitability class Soil unit Description Limitations /Management Highly suitable Moderately suitable Sampa Assoc – 1A, 1B Gentle undulating 1) Gravelly subsoil Banda Assoc – 2A topography. The soils 2) Patches of soils Debibi Assoc – 3A are deep, have good shallow to Drobo Assoc drainage on the uplands ironpan Bekwai-Oda Assoc and consist of sandy Dumboli Assoc loams and sandy clay loams with moderate amounts of ironstone concretions and quartz gravel at varying depths within the subsoil. They are suitable for a variety of crops / trees including maize, cassava, cashew, teak Marginally suitable Banda Assoc – 2B Soils are skeletal, 1) Abundant Debibi Assoc – 3B containing abundant ironstone ironstone and quartz concretions/ gravel. Crops like maize, quartz gravel in cashew, teak are profile marginal on these soils 2) Some profiles are shallow to ironpan Not suitable Banda Hill Consociation Consists mainly of rock Steep, hilly, rocky with – 2C outcrops, boulders and very shallow soils Foamang Consociation skeletal soils on hill ranges

Map 3. Soil suitability

4.0 CONCLUSION

The Tain District, which falls within The Tain River Basin soil survey region of the Soil Research Institute had not experienced much soil survey work apart from the detailed reconnaissance work carried out by E. O. Asare. Subsequent detailed soil surveys were carried out in Wenchi Municipality which is part of the Tain River Basin. With the construction of the Bui Dam it is expected that the District will open up with more attention going into soil and related studies for rainfed and irrigated agriculture.

References

1. Asare E. O. 1961 The Lower Tain Basin, Ghana: Problems in Agricultural Development. Ghana Ministry of Agriculture, Scientific Services Division. Division Paper No. 12, Accra

2. CSIR-Soil Research Institute (undated) Draft report on Soils of the Tain River Basin

3. CSIR-Soil Research Institute ( ) Soil map of the Tain River Basin

APPENDIX

1. Debibi Association

Toposite Lithology Soil series Position Description of soil Notes modification Upland Peneplain drift Duadaso Summit Deep, well drained, 150 cm of non- Subseries is Assoc soils /Upper gravelly clay loam overlying seepage iron 45-75 cm slope pan. Subseries is Buku series to pan Namasa Summit Greyish Brown topsoil overlying pale Occurs in brown silty clay loam subsoil. Gets shallow waterlogged in wet periods. depressions Jamra Summit 120 -150 cm pale grey silty clay loam. It is mottled. It is flooded in the wet season Afrancho Upper Deep, non-gravelly, brown, light clay, slope about 150 cm deep. Associated with forest soils of Bekwai, Nsuta, Nzima

Concretionary Wenchi Summit Shallow; concretionary soil overlying sheet soils /Upper iron pan at 30cm. Adamu Upper 90-120 cm of silty clay loam with Assoc with abundant ironstone concretions and Duadaso, quartz grit overlying indurated layer Morle Morle Upper 30-90 cm of ironstone concretions and boulders of ironpan overlying sheet ironpan. Has silty clay loam texture Nsuta Upper A highly gravelly layer of about 75 cm thick overlying sheet ironpan Sampa Upper Reddish brown concretionary silty clay 50-70% loam, 150cm deep, gravel Nsawkaw Middle Orange brown concretionary light clay consisting of 120cm of gravel. Atonsu Middle About 90-120 cm orange brown silty clay loam with abundant concretions overlying a semi-indurated layer.

Sedentary soils Bekwai Upper Deep (120-150 cm), well drained, gravelly, mainly quartz, reddish brown silty light clay Nzima Middle Moderately well drained associate of Bekwai series. Brown, gravelly (quartz) silty light clay Drobo Upper Reddish brown, gravelly, mainly quartz Savanna of 120-150 cm, light clay. Well drained Bekwai Debibi Orange brown drainage associate of Savanna of Drobo series. 120-150 cm of gravel, mainly Nzema quartz

Debibi Association - continued

Toposite Lithology Soil series Position Description of soil Notes modification UPLAND Sedentary Kasampiri Mod Shallow skeletal soil usually over Rarely soils steep 10% slope. Consists of 45 – 60 cm encountered slopes partially decomposed rock grading into bedrock Piedmont Amanfonso Foot of Yellowish brown non-concretionary drift soil hills light clay, 90-120cm deep overlying a concretionary layer

LOWLAND Colluvial drift Kresua Lower Pale brown, silty light clay, 90-120 Savanna? soils slope cm deep with a stone line at the base. Kokofu Middle Pale brown, about 90-120 cm silty Forest & Lower clay overlying weathering rock Buni Lower Poorly drained; consists of 40-50 cm of silty light clay overlying a concretionary layer which rest on decomposing rock Goka Lower Light grey; consists of 120-150 cm Concretionary of small rounded, polished ironstone concretions overlying decomposing rock

Alluvial drift Mampa Bottom Consists of 150 cm or more of clay soils that cracks when dry. Water table is fairly high during the wet season Oda Bottom Consists of about 120-150 cm of grey silty light clay.

2. Sampa Associatiom

Toposite Lithology Soil series Position Description of soil Notes modification Upland Peneplain Duadaso Summit Deep, well drained, 150 cm of non- Subseries is Assoc drift soils /Upper gravelly clay loam overlying seepage 45-75 cm slope iron pan. Subseries is Buku series to pan Namasa Summit Greyish Brown topsoil overlying pale Occurs in brown silty clay loam subsoil, about shallow 45-60 cm deep which overlies a depressions concretionary layer underlain by iron pan. Gets waterlogged in wet periods. Wenchi Summit Shallow; concretionary soil overlying /Upper sheet iron pan at 30cm.

Concretionary Morle Upper 30-90 cm of ironstone concretions Assoc with soils and boulders of ironpan overlying Wenchi, associated sheet ironpan. Has silty clay loam Drobo & with texture Sampa peneplain Sampa Upper Reddish brown concretionary silty 50-70% drift soils clay loam, with an indurated layer at gravel a depth of 60 – 140 cm. The layer is easily penetrated Nsawkaw Middle Orange brown concretionary light Deep to lower clay consisting of 120cm of gravel. gravelly nature

Sedentary Drobo Upper Reddish brown, gravelly; 120-150 Savanna of soils cm, light clay of quartz and ironstone Bekwai gravel (50-70% by volume). It is well drained Debibi Orange brown drainage associate of Savanna of Drobo series. 120-150 cm of quartz Nzema and ironstone gravel (50-70%).

Piedmont Kasampiri Mod Shallow skeletal soil usually over drift soils steep 10% slope. Consists of 45 – 60 cm slopes partially decomposed rock grading into bedrock Amanfonso Foot of Yellowish brown non-concretionary hills light clay, 90-120cm deep overlying a concretionary layer

Sampa Association - continued

Toposite Lithology Soil series Position Description of soil Notes modification LOWLAND Colluvial drift Kresua Lower Pale brown, silty light clay, 90-120 Savanna? soils slope cm deep with a stone line at the base. Buni Lower Poorly drained; consists of 40-50 cm of silty light clay overlying a concretionary layer which rest on decomposing rock Goka Lower Light grey; consists of 120-150 cm Concretionary of small rounded, polished ironstone concretions overlying decomposing rock

Alluvial drift Mampa Bottom Consists of 150 cm or more of clay soils that cracks when dry. Water table is fairly high during the wet season Chichiwere On Pale brown, alluvial soil with loamy raised sand texture banks of streams

3. Banda Association

Toposite Lithology Soil Position Description of soil Notes modification series Upland Peneplain Bofe Summit Deep (150 cm), reddish brown, non- Assoc drift soils gravelly, sandy light clay overlying sheet ironpan or weathered quartzite Bau Upper Deep (>150cm), brown, sandy light clay overlying either sheet ironpan or weathering quartzite

Concretionary Banda Upper Consists of 20cm of loamy fine sand soils overlying brown sandy light clay. It contains about 50-70% gravel (by volume) Bungase Summit Deep and gravelly. Consists of 50-70% & Upper of gravel (by vol), mainly ironstone concretions overlying decomposing schist at about 183 cm. It is reddish brown and has sandy light clay texture Menji Middle It’s a brown concretionary soil. Water table Consists of about 183 cm of sandy at about light clay with abundant manganese 130 cm dioxide and ironstone concretions during the overlying weathering quartzite wet season Wenchi Summit Shallow; concretionary soil overlying /Upper sheet iron pan at 30cm. Morle Upper 30-90 cm of ironstone concretions and boulders of ironpan overlying sheet ironpan. Has silty clay loam texture Sedentary Kanka Summit Shallow brashy soil. Consists of 100 – soils / Upper 152 cm of sandy loam with abundant of steep pieces of weathering quartzites or hills schist overlying weathering rock. Piedmont Lura drift soils Farming

Banda Association - continued

Toposite Lithology Soil series Position Description of soil Notes modification LOWLAND Colluvial drift Gradau soils Sase

Ngre

Alluvial drift Landa soils Mua Lapla

3.3