Ical inputs, to meet the ever increasing need for food animal feed fibre, and fuelwood has already ready resulted in accelerated land degradation and loss of soil productivity (stoorvogel et al 1993 tolba1993) despite many decades of research on the intensification of agriculture on rainfed uplands in the humid and subhumid tropics efforts to develop altemative sustainable and more productive food crop production systems have far had only limited success (Kang et al 1991)