Classification Land use problems: Soil fertility decline is the basic problem: this is due to degradation and nutrient mining. Loss of limited rainwater by runoff and loss of soil cover result in low crop production and food insufficiency. This occurs in combination with lack of pasture, resulting in shortage of manure. Land use
silvopastoralism (before)
annual cropping (rainfed) (after)
Climate
Degradation
semi-arid, tropics
soil erosion by water: loss of topsoil/ surface erosion
Stage of intervention
Conservation measure
soil erosion by wind: loss of topsoil/ surface erosion
chemical soil deterioration: fertility decline and reduced organic matter
physical soil deterioration: compaction, sealing and crusting
Origin
Prevention Mitigation / Reduction Rehabilitation
structural: stone lines, planting pits
agronomic: manure application (supplementary)
Level of technical knowledge Land user's initiative Experiments / research Externally introduced: < 10 years ago
Agricultural advisor Land user
Main causes of land degradation: Direct causes - natural: droughts Indirect causes: land tenure, poverty Main technical functions: - increase in organic matter - increase of infiltration - increase / maintain water stored in soil - water harvesting / increase water supply - increase in soil fertility - increases natural regeneration of trees
Secondary technical functions: - reduction of slope length - improvement of ground cover - improvement of soil structure
high moderate low insignificant
Environment Natural Environment Average annual rainfall (mm) > 4000 3000-4000 2000-3000 1500-2000 1000-1500 750-1000 500-750 250-500 < 250
Altitude (m a.s.l.)
Landform
> 4000 3000-4000 2500-3000 2000-2500 1500-2000 1000-1500 500-1000 100-500 <100
Slope (%)
plateau / plains ridges mountain slopes hill slopes footslopes valley floors
flat gentle moderate rolling hilly steep very steep
Soil depth (cm) 0-20 20-50 50-80 80-120 >120
Growing season(s): 90 days (June until September) Soil texture: coarse / light (sandy) Soil fertility: low Topsoil organic matter: low (<1%) Soil drainage/infiltration: good, though infiltration is low where there is a crust
Soil water storage capacity: low Ground water table: no data Availability of surface water: no data Water quality: no data Biodiversity: no data
Tolerant of climatic extremes: no data Sensitive to climatic extremes: no data If sensitive, what modifications were made / are possible: no data
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Water Harvesting – Guidelines to Good Practice