Soil nutrient enhancement by rice husk in smallholder farms of the tropical zone.
Soil serves as both reservoir and resource of plant nutrients. When soil is unable to meet the requirements of plants, it is consider to be constrained. Low nutrient availability, retention, and holding, high acidity and low organic matter content are some constraints to soil productivity. A large proportion of soils in the humid tropical zone of Nigeria have low inherent fertility, a major biophysical root cause of declining per-capita food availability in smallholder farms. Emerging evidences attribute this to insufficient nutrient inputs relative to nutrient export primarily through harvested products. Soil fertility management is one of the most cherished natural resource that requires being safeguard at all cost. An adequate and better solution to combat soil constraint arising from nutrient depletion has been developed; a low external input technology, amending soils with an organic base fertilizer (rice husk) as it is high in organic carbon (302 g kg-1), potassium (1.02 C mol kg-1), nitrogen (2.72 %) and phosphorus (99.12 mg kg-1). These nutrient values are rated as high for humid tropical soils and are considered the most limiting nutrients in the humid tropical soils. Maize yield in 1999 and 2000 and rice yield in 1999 and 2003 cultivated using rice husk showed significantly higher yield when compared with the control (no rice husk used). Yield measured using different rates of rice husk and the control showed high variability (CV > 35 %). Rice husk helps in building up soil organic matter (SOM) thus enhancing nutrient retention and water-holding capacity. It is readily available, affordable, sustainable and ecologically sound. It is a local resource, natural and safe to soils, crops, humans, and animals. Indeed it is the return to organic farming.
Keywords: Rice husk, SOM, soil constraint, tropical soil, sustainable
JOAFSS Vol. 4 (1) 2006: pp. 105-113