442

9F

9F

FOOD

V.424

(August 1996)

P.1-9

Cocoa,Gliricidia,Hydrology,Soil conservation,Soil erosion,Sustainability,tree crops

Soil erosion is a major process of land degradation. Effective soil erosion management is therefore a vital part of the quest for sustainable agriculural production. In tree-crop ecosystems in the humid tropics, the processes of soil erosion operating under the tree canopy are assciated with the large-scale flow of surface water during high-intensity rainstorms. Research carried out in Malaysia has shown that a cocoa-Gliricidia ecosystem which maintains dense surface vegetation,together with circle weeding, satisfied many indicators of sustainability. In comparison with an adjacent clean-weeded area, soil loss associated with the improved practice was extremely low, peak runoff rate was low, runoff was delayed loss of nutrients was reduced, and plant growth enhanced. In many tropical tree-crop ecosystems, leaf litterfall returns nutrients to the soil. However,under slopeland conditions during wet spells, there was rapid mobilization of leaf litter. This is an important process of nutrient displacement. Living surface vegeation effectively controlled this process.

1376/12

Shahsavary

GN135147