Decomposition rate of fresh organic cowpea fodder as influenced by intra-row spacing, clipping height and time on soils fertility conservation for sustainable agricultural productivity in savannah region of Nigeria

Abstract

The vagaries of climate, particularly temperature and moisture conditions are known to affect the rate of decomposition. Under tropical and sub – tropical climate, the rate of decomposition which determines the amount of plant nutrients released into the soil has been estimated for a number of crops. However, for the leguminous dual purpose crops like cowpea, Vigna unguiculata (L) Walp, little or virtually no studies on this aspect has been documented in spite of the significant contributions of legume to soil (nitrogen enrichment). Good soil health is a pre-requisite for good plant health. But high doses of nitrogen fertilizers lead to high nitrogen content in the crop with all the attendant health hazards. However, this danger is less when fertilization is organic; as organic matter when decomposed releases nutrient gradually. Results of studies in the savannah soils of Samaru, Zaria, Nigeria, on cowpea sown at high population densities, and under an innovative clipping management, with time, showed that mean fodder yields of 7 – 19 t ha -1 were produced and about 62% fresh fodder was obtained when plants were clipped at 74 days after planting (DAP) than at 64 DAP. It took 18 – 24 and 27 – 35 days for the leaves and stems added on the soil surface, and 32 – 40 and 43 – 53 days for the leaves and stems buried into the soil to decompose respectively. The ability of cowpea fresh fodder to decompose when incorporated into the soil could facilitate the release of an appreciable amount of stored plant nutrients such as N; and more so improve the health of the soil through an increase in soil (organic content, organic matter and cation exchange capacity contents). This innovative farming practice could hold the key to rejuvenating the degraded savannah soils of Nigeria and other tropical countries; creating hope in the effort towards the eradication of hunger and poverty and ensuring food security through sustainable agricultural productivity.