ABSTRACT
Humid tropics extend on either side of the equatorial belt from 0 to 25° latitude. The vegetation includes a diverse species of perennial forest tree species, shrubs, annuals and farming belts. In this chapter our focus confines to cropping zones. Cereals (e.g. maize, rice, sorghum), root crops (cassava, yam, sweet potato) and legumes (e.g. beans, cowpea, soybean) are common to this agroecosystem. Globally, warm humid and sub-humid tropical agricultural zones extend into nearly 11% of total agricultural area, wherein 30.4% of global population resides (Wood et a l 2000). Among the various crops cultivated in humid tropics, the emphasis within this chapter has been confined to cassava, for the sake of brevity of this book. Cassava is an important crop preferred by the farming community because of its low nutrient and energy input requirements. In many parts of humid tropical Africa, Latin America and Asia, roots and tubers (e.g. cassava) constitute important, supplemental sources of carbohydrates, vitamins and amino acids. Frequent shortages of chemical fertilizer inputs, and limited irrigation facilities encountered by farmers in humid tropics
makes cassava the appropriate choice. Globally, cassava-based agroecosystem extends into 20 m ha, and is expected to increase to 24 m ha by 2020. The present production at 175 mt is expected to reach 290 mt by 2020 (IFRRI, 1998; FAOSTAT, 1999). According to Scott et al. (2000) increase in the cassava growing belt and its consumption has been rapid, at a growth rate of 3.1% per year in tropical Africa.
