The world leading cassava producers, i.e. Nigeria and Brazil,
however, do not have much improvement in root productivities in the past 10 years; only by
2.10 tons/hectare (from 9.70 to 11.80 tons/hectare since 2000 to 2008) and by 0.35
tons/hectare (from 13.55 to 13.90 tons/hectare since 2000 to 2009), respectively.
The production of cassava can be simply increased by expanding planting areas.
Nevertheless, in most regions, no new marginal land is accessible as well as forestry areas
are not allowed for area expansion. Moreover, in some countries, there is a competition for
land uses among other economic crops such as sugar cane and maize in Thailand. The
sustainable and effective means of increasing root production should be achieved by an
increase in root productivity. Yields or root productivities of cassava roots vary significantly
with varieties, growing conditions such as soil, climate, rainfall as well as agronomic
practices. Better root yields can be obtained by well-managed farm practices including time
of planting (early of a wet season), land preparation (plowing by hand or mechanically and
ridging), preparation of planting materials (ages of mother plants, storage of stems, length &
angle of cuttings, chemical treatment), planting method (position, depth of planting and
spacing), fertilization (type of fertilizers – chemical vs. organic, dose , time and method of
fertilizer application), erosion control, weed control, irrigation and intercropping (Howeler,
2001; 2007). The agronomic practices implemented by farmers vary markedly from regions
to regions, depending greatly on farm size, availability of labor, soil and climatic conditions
as well as socio-economic circumstances of each region (Table 3). It is very interesting to
note that the highest root productivity was reported in India (i.e. 40 tons/hectare) which
was irrigated cassava rather than rainfed one, with a highest amount of fertilizer
application. In some planting areas such as in Thailand, irrigation is now introduced instead
of relying only on rainfall. Yet, the investment cost is high and farmer’s decision is upto
market demand, price of cassava roots as well as other competitive crops. By effective farm
management, it is expected that the root productivity can be increased twice, from 25 to 50
tons/hectare. By combining that with varietal improvement, the root productivity can be
potentially improved upto 80 tons/hectare (Tanticharoen, 2009).
The production cost of cassava is classified into fixed costs and variable costs. The fixed
costs include land rent, machinery, depreciation cost and taxes. The variable costs are
consisted of labor costs (for land preparation, planting material preparation, planting,
fertilizer & chemical application, weeding, harvesting and irrigation) and others including
planting materials, chemicals (herbicides, sacks), fuels and tools. Except China, all countries
demonstrate that the labor cost is greater than 40% of total production cost. In particular, the
labor cost as well as the fixed costs of cassava plantation in India is quite high comparatively
to other countries, making their production cost quite high. A semi-mechanized practice for
cassava plantation is therefore developed in some countries such as Brazil and Thailand in
order to minimize the labor cost, and hence total production cost.