Shortened fallows do not allow soils to recover. They quickly lose their productive potential and become highly erodible. Traditional agroforestry systems must be improved so as to increase subsistence and market produce from limited land areas over time. In more modern, more intensive agroforestry systems, trees are not just tolerated or passively allowed to regenerate during fallows. Deep tree roots take up soil nutrients and moisture that are out of reach of root crops.
Trees shelter crops and soil surfaces from drying winds and intense sun.
Tree-leaf mulch retains moisture in upper soil layers. Trees serve to continuously sustain rather than periodically rebuild soils. Fallow requirements are reduced, leaving more land in production at any one time. Trees protect the soil and crops from damaging, erosive, and drying winds. Tree roots bind soil, preventing down-slope erosion during rains.