Influence of poultry manure and inorganic nitrogen fertilizer on grain yield and proximate component of two cultivars of cowpea (Vigna unguiculata (L.) Walps)

A study on the influence of poultry manure and inorganic nitrogen fertilizer on grain yield and proximate composition of two cultivars of cowpea (Ife Brown and IT86D - 719) was carried out at the Teaching and Research (T&R) Farm of the Obafemi Awolowo University, (O.A.U.) Ile - Ife, Nigeria. The two cultivars of cowpea were planted in a randomised complete block design (RCBD), laid out in a split-plot arrangement in two seasons and treated with four sources of fertilizer (inorganic fertilizer (IF), mixture of inorganic fertilizer and poultry manure (IFPM), poultry manure (PM) and no fertilizer or manure treatment referred to as the control (C). Each fertilizer source supplied 20 kg N/ha basal dosage. The variability and diversity observed were due to the genotypic variations of the crops and response to the fertilizer levels. The effect of the poultry manure and inorganic fertilizers on yield /yield components and proximate composition were significantly different from the control. Grain yield and yield components (the number of peduncles per plant (PEP), peduncle length (PEL), number of pods per plant (POP), dry pod weight (PDW), biomass (BM) and grain yield per plant (YLD/PLT)) were affected by the fertilizer levels, seasonal changes, cultivars; thus having significant influence on the final yield of the two cultivars; while pod length (PL), number of pods per peduncle (PPE), number of seeds per pod (NSP), 100SW were not. The crude protein, percent crude fibre, total nitrogen and carbohydrate content of the grains varied among cultivars and were significantly improved by fertilizer source, especially IFPM and PM. The significant response observed in the nutritional composition indicated differential utilization of nutrients under different treatments. The differential response of Ife Brown and IT86D-719 to poultry manure and inorganic fertilizer is clearly manifested on the grain yield, crude protein, percent crude fibre, total nitrogen and carbohydrate content of the grains of the two cultivars. Key Words: cowpea; cultivars; nutrient source; poultry manure; proximate composition; yield Moor J. Agric. Res. Vol.4(1) 2003:37-45