The use of crop residues, “organomineral fertilizers,” and other locally
available plant nutrient materials for ameliorating problems of soil acidity
have been emphasized recently in studies of fertility of tropical soils. Meaningful
contributions to soil nutrient pool and beneficial effects on subsequent
crops have been observed when crop residues were returned to farmland and
especially if the residues are of immediate utilizable form (Shanmugam, Rathnasamy,
and Nadarajan 1996; Omueti et al. 2000). It has been reported
(Omueti et al. 2000) that organic matter has a liming effect on soil; rice
husk (RH), a crop residue of the rice production enterprise, has been used
in agriculture as a soil amendment or soil conditioner and for growing vegetables
hydroponically (Solomon and Ogeh 1995; Swarup 1986). In some
instances where RH was used, it had often been incorporated for at least 3
weeks or more, at times up to a season, before planting. However, some
periods are too short to aid complete decomposition of nutrients locked up
in the organic matter to be released and be made available, considering its
high C:N ratio of about 50:1.