Vector Members The E00 files are in Arc/Info Export format and should be imported with the ... Arc/Info command Import cover In-Filename Out-Filename.
The African Irrigable Soils dataset is part of the FAO Irrigation and Water Resource Potential for Africa. The base map used was the UNESCO/FAO Soil Map of the World (1977), scale 1:5000000 and Miller Oblated Stereographic projection. All sources were re-registered to the basemap by comparing known features on the basemap and the source maps. The digitizing was done with a spatial resolution of 0.002 inches or 0.05 mm. The maps were then transformed from inch coordinates to latitude/ longitude degrees. The transformation was done by an unpublished algorithm (by US Geological Survey and ESRI) to create coverage"'"s for one-degree graticules. The source includes a list of attributes for each soil unit including: slope, drainage, texture and phase (re: UNEP/FAO/ESRI ITU 100004). All these components were used in the evaluation of potential irrigable soils. Criteria by FAO were established to estimate the proportion of each component soil which would meet irrigation requirements. This is done in two case. Criteria were established for: - Growing food crops under irrigation which is called upland crops; - Lowland crops, flooded rice. Then for both cases two maps were generated. One with all soils which are suitable, and one where slope, texture, drainage and phase were considered. Each different soil type is classed according to suitability, S1 irrigation with no constrains, S2 irrigation with some constrains, N1 not suitable without major improvements, N2 permanently not suitable. Because one soil unit can consist of more soil components (unit Af26-a can mean 30%Bf and 70% Af) the suitability is expressed in percentage of the unit that is suitable (1 >50% suitable, 2 = 25-50% etc.). Then the soil characteristics are used to refine the ranking. This refining is done were the original soil rank is increased decreased or changed from their original suitability to a new suitability (so or soil gets new class S1, N1 etc. or ranking changes like, -1 lower soil rank by one, +1 raise soil rank with one). The Ranking of Soils is as follows
Miscellaneous land units such as rock debris, desert debris,
Soils with stonic, lythic or petrogypsic phase.
Ranking by Drainage conditions All crops Lowland Fluvisols and Histosols 50% S1, 50% S2 50% S1, 25% S2 , 25% N1 Gleysols and Gleyic units 50% S2, 50% N2 50% S1, 50% N2 (except Cambisols) Gleyic Cambisols 100%S2 100%S1 Planosols 50% S1, 50% N2 50% S1, 50% S2
Ranking by Special conditions Calcaric units 50% S1, 50% S2 50% S2, 50% N2 Vertisols 50% S2, 50% N2 100% S2 Acrisols,Nitiosols,Ferrasols -1 -1 Solonchalks,Solonetz -1 -1 Thionic Fluvisols 100% N2 100% S1 Ranking of Slope conditions All crops Lowland crops 0-8% Fluvisols,Gleysols,Gleyic unit no change no change All other soils 50% S2, 50% N1 50% S2, 50% N1 8-30% all Soils 100% N1 100% N2 >30% all Soils 100% N2 100% N2 Ranking of Soil Texture conditions Coarse textured 25% S2, 75% N2 100% N2 Medium textured no change no change Fine textured -1 no change
Contact : FAO, Land and Water Development Division via Delle Terme di Caracalla, 00100, Rome, Italy
Att: Mr. Thomas
The IRRIGUT file shows all soils that are irrigable for upland crops. The IRRIGUB file shows soils that are irrigable for upland crops, ranked by slope etc. The IRRIGLT file shows all soils that are irrigable for lowland crops The IRRIGLB file shows soils that are irrigable for lowland crops, ranked by slope etc.
ESRI. Final Report UNEP/FAO world and Africa GIS data base. (1984). Internal Publication byESRI, FAO and UNEP
FAO, UNESCO. Soil Map of the World (1977). Scale 1:5000000. UNESCO, Paris
UNESCO. Geological Map of Africa (1975). Scale 1:1000000
FAO. Irrigation and Water Resource Potential for Africa. (1987) Publication FAO, AGL/MISC/11/87. Rome, Italy
Source : FAO Soil Map of the World, scale 1:5000000 Publication Date : Nov1987 Projection : Miller Type : Vector Fromat : Arc/Info export non-compressed Related Datasets : All UNEP/FAO/ESRI Datasets ITU08-10 (100004) - Integrated Terrain Units AQRANK, AQRANKSM (100046) WATERBALLX FAO (100053) - Waterbalance CROPS2 (100013) - Crops by administrative unit ADMIN (100012) - Administrative units WSHDLL (100018) - Watersheds RAINFALL (100009) - Mean Annual rainfall SOILS FAO/Unesco soil map (100007)