Land Capability Classification
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LIMITED CIRCULATION ANRS Investment Office Potential Survey, Identification of Opportunities and Preparations of Projects Profiles and Feasibility Studies Part One: Potential Assessment Survey Soil Survey Draft Report Development Studies Associates (DSA) and Shawel Consult International (SCI) August 2005 1 Table of Content 1. Introduction .................................................................................................................... 1 1.1. General ..................................................................................................................... 1 1.2. Objective and Scope ................................................................................................ 1 2. Study Methodology ....................................................................................................... 1 2.1. General ..................................................................................................................... 1 2.2. Pre Field Activities .................................................................................................. 2 2.3. Field Soil Survey...................................................................................................... 2 2.4. Post Field Work Activities ....................................................................................... 3 2.5. Soil Classification and Mapping .............................................................................. 4 3. The Soils of the Amhara Region .................................................................................... 5 3.1. General ..................................................................................................................... 5 3.2. Soil Classification and Mapping .............................................................................. 6 4. Soil Mapping Units ......................................................................................................... 6 4.1. General Physiography of the Region ....................................................................... 6 4.2. Geology .................................................................................................................... 7 4.3. Mapping Unit Characterization................................................................................ 9 4.4. Description of the Mapping Units.......................................................................... 11 5. Description of major soils in the region ...................................................................... 51 5.1. Vertisols ................................................................................................................. 51 5.2. Nitisols .................................................................................................................. 52 5.3. Luvisols ................................................................................................................. 53 5.4. Alisols ................................................................................................................... 53 5.5. Acrisols ................................................................................................................. 53 5.6. Phaeozems............................................................................................................. 54 5.7. Fluvisols ................................................................................................................. 54 5.8. Gleysols................................................................................................................. 54 5.9. Andosols ................................................................................................................ 55 5.10. Calcisols ............................................................................................................... 55 5.11. Cambisols ............................................................................................................. 55 5.12. Arenosols ............................................................................................................. 57 5.13. Regosols ............................................................................................................... 57 5.14. Solonetz................................................................................................................ 57 5.1.5. Leptosols ............................................................................................................. 58 6. Soil and Land Management ........................................................................................ 59 6.1. Watershed Management......................................................................................... 59 6.2. Soil Fertility ........................................................................................................... 60 6.3. Flood Prevention and Drainage ............................................................................. 61 6.4. Management of Soline and Sodic Soils ................................................................. 62 a 6.5. Management of Vertisols ....................................................................................... 62 References ....................................................................................................................... 64 b 1. Introduction 1.1. General This report presents the findings of the soil resources survey of the Amhara Region. The study was based mainly on field survey, secondary data collection, field verification and analysis of previous land resources studies in the Region. Soil mapping units which were designated separately by different studies were converted and unified. The outcome of the study is the preparation of soil resources study report and maps at a quarter million scale covering the whole Region including existing information, field surveys, laboratory analysis and mapping interpretation for land development. The terminology used in this report for soil description and taxonomic soil classification is explained in Keys to soil Taxonomy, USDA (1996), FAO-ISRIC Soil and Terrain Data Base (SOTR, 1995) and FAO 1990. 1.2. Objective and Scope The Investment Office of the Amhara National Regional State required the identification of the potential and constraints of the soils to facilitate decision-making on the allocation of land for different investment endeavors. The approach to achieving these goals is to identify, describe and map the soils of the Region at the appropriate level of intensity. Within the overall Region wide comprehensive inventory of the natural resources, the objective of the land resources study is to identify, describe and map the soils at a scale of 1:250,000. 2. Study Methodology 2.1. General The study methodology of the soil resources of the Amhara Region has been based on the objective of the study and scope of work. The prime objective of the study is to determine the overall distribution of the different types of soils in the Region and mapping them at a scale of 1:250,000 inorder to identify the potential and constraints of the land resources for economic development. To achieve the intended goal, the study was phased into three district activities. 1 2.2. Pre Field Activities Review of previous soil studies was carried out and all available relevant documents to this study including: (i) River basin development master plan studies (ii) Comprehensive large area land resources studies and (iii) Site specific project studies (iv) Primary data collected from field surveys. The review of the previously established data bases, however, revealed that there were areas of the Region where very little or no land resources information was available such as the northern Awash Basin which falls within the Amhara Region. Areas to be studied were delineated on the 1:250,000 scale topographic maps provided from the Ethiopian Mapping Authority. Soil profile pits and auger borings were located in areas which were considered to be representative for a larger area with similar retentions between land terrain and soil characterstics. The different soil surveys in the Region used different soil survey systems and therefore, required reconciliation and rationalization inorder to unify them. The unifying system employed to accommodate all the different soil survey systems was basically based on the combination of soil type and landform as mapping unit. A generalized verification plan was prepared for the areas where soil studies have already been conducted. The data basis of the previous studies were carefully investigated and were used to compile the maps and the accompanying reports. 2.3. Field Soil Survey The field soil survey was conducted by two groups operating in different parts of the Region where the data gap has been identified. The soil survey activities employed a combination of field verification of the previously surveyed areas and field soil study in selected areas which were considered to have very little or no soil survey information in nineteen weredas falling within North Wello zone, South Wello Zone, Oromiya Zone and North Shewa Zone. Soil profile pits and auger borings were located in areas which are considered to be representative for a larger area with similar relations 2 between terrain and soil characteristics. The soil profile pits were described in detail following FAO pit description guidelines. In addition mini pits of about 0.60m depth were dug in several sites where the soils variability is high and where confirmation