Agricultural Potential of the Soils of Botswana
The aim of the work is to create a soil map atlas of Botswana.
Between the years 1990-2000 agricultural soil surveys were conducted on a scale of 1:250,000.
1. Two soil maps of Botswana at a 1:1,000,000 scale – BOT/85/011 REPORT. Those maps include a unique legend and a unique method of encoding.
2. 41 soil maps at a scale of 1:250,000 – BOT/85/011 REPORT.
3. A report which accompanies the 41 soil maps: “REVISED GENERAL SOIL LEGEND OF BOTSWANA- BOT/85/011 REPORT, FIELD DOCUMENT 32”
The surveys focused on the soils, vegetation, land suitability and other agricultural aspects. The maps are accompanied by detailed reports on soil characteristics, morphology, conditions formation and materials.
In the year 2000, whilst preparing Botswana’s Agricultural Master Plan for the development of agricultural projects throughout the country, the need for detailed data regarding soil conditions and agricultural lands characteristics became apparent.
Within the project’s framework, the existing soil data was interpreted in order to be implemented to the country’s agricultural needs. This interpretation was conducted in cooperation with soil experts from Botswana’s Ministry of Agriculture; resulting in “Botswana’s soil Atlas” which serves as a basis for agricultural development and implementation.
Analysis and interpretation of soil units as they appear on soil survey maps and translation to agricultural values on the following topics:
A series of agricultural maps depicting soil properties.
• Flat - Slopes not steeper than 0,5%)
• Almost flat - Steepest slopes between 05-2%
• Slightly/gently undulating - slopes between 2-5%
• Undulating - Steepest slopes between 5-8%
• Rolling - Steepest slopes between 8-16%
• hilly - Steepest slopes between 16-30%
• very deep ( >150 cm)
• deep (100-150 cm)
• moderately deep (50-100cm)
• shallow (25-50cm)
• very shallow (0-25 cm)
• excessively drained (water is removed from the soil very rapidly)
• somewhat excessively drained (water is removed from the soil rapidly)
• well drained (water is removed from the soil readily but not rapidly. Well drained soils commonly retain optimum amount of moisture for plants growth)
• moderately well drained (water is removed from the soil somewhat slowly, so that the profile is wet for a small but significant period of time)
• imperfectly well drained (water is removed from the soil slowly enough to keep it wet from significant periods but not all of the time)
• poorly drained (Water table removed from the soil so slowly that the water table remains at or on the surface most of the time)
• Coarse textured: sands, sandy loams, loamy sands.
• Medium textured: sandy clay loams, clay loams, silty clay loams, loams, silt loams, silt.
• Fine textured: clays, silty clays, sandy clays. The texture categories are identical to the standard terminology of the FAO. The texture samples were taken in a 100cm depth.
• flat (slopes not steeper than 0,5%)
• almost flat (steepest slopes between 05-2%)
• slightly/gently undulating (steepest slopes between 2-5%) • undulating (steepest slopes between 5-8%)
• rolling (steepest slopes between 8-16%) v hilly (steepest slopes between 16-30%) The topography categories are an extension of the 3 FAO standard categories.
• >161 mm/m
• 110-160 mm/m
• 70-109 mm/m
• 40-69 mm/m
• 20-39 mm/m
•-3 high (7.51-8.3)
• 0 correct (5.51-7.5)
•-2 low (4.5-5.5)
•-4 very low (20.1 (Meq/100gr)
• 1 10.1-20 (Meq/100gr)
• 1 5.1-10 (Meq/100gr)
• 1 <5 (Meq/100gr)
The Exchangeable Cation Capacity (CEC) represents the average values
Received from the top 100 cm soil profile Creation of maps Land
Capability Classification and L.C.F.I
USDA Land Capability Classification
A grouping of capability subclasses that have the same relative degree of limitation or hazard:
Class I – Soils with few limitations that restrict their use
Class II – Soils with some limitations that reduce the choice of plants or require moderate conservation practices
Class III – Soils with sever limitations that reduce choice of plants or require special conservation practices
Class IV – Soils with very severe limitations that restrict the choice of plants, require very careful management or both
Class V – Soils with little or no erosion hazard