Effect of Phosphorus Fertilizer and Spacing on Growth, Nodulation Count and Yield of Cowpea (Vigna unguiculata (L) Walp) in Southern Guinea Savanna Agroecological Zone, Nigeria

The experiments were conducted during 2009 and 2010 rainy season at the research and teaching farm of the college of agriculture, Lafia, Nasarawa state, Nigeria. To determine the effect of phosphorus fertilizer and spacing on growth, nodulation count and yield of cowpea (Vigna unguiculata) in southern guinea savanna agroecological zone, Nigeria. The treatments consisted of three levels of phosphorus 0, 20 and 40 kg/ha and three levels of spacing: 15x40, 30x60 and 45x80 cm factorially combined to form nine treatments which were laid in a Randomized Complete Block Design (RCBD) and replicated three times to form twenty seven plots. The result showed that Phosphorus fertilizer had a significant (p<0.05) effect on the entire growth and yield parameter assessed in both years. 40 kg/ha of phosphorus gave a significantly higher number of nodulation count/plant (34.95 and 32.24), number of pod/plant (20.64 and 20.24), seed weight/plant (39.56 and 37.64), pods weight/plant (51.45 and 45.31) and seed weight/ha (1.56 and 1.52 t/ha) in both years. The spacing also had a significant (p<0.05) response on almost the entire growth and yield parameter assessed except on the weight of 100 seeds. Spacing of 30×60 cm did not differ significantly with 45x80 cm which gave similar result in the no. of pod/plant, seed weight/plant, pods weight/plant and seed weight (t/ha) in both years.