Effect of Cattle Manure and Calcium Ammonium Nitrogen on Growth and Leaf Yield of Local Cowpea Accessions in Coastal Kenya

Cowpea is one of the major food crops contributing to food security and poverty alleviation especially among women and resource-poor farmers in marginal areas in Kenya. The effect of different concentrations of cattle manure and inorganic nitrogen (Calcium ammonium nitrate, CAN) application on growth and fresh and dry leaf yields from single and multiple harvest of four local vegetable cowpea accessions, Mnyenze madamada, Sura mbaya, Katsetse and Usimpe mtu mdogo, was studied over two seasons at Mtwapa in coastal Kenya. The research was conducted in a randomized complete block design with three replications with treatments arranged in a factorial arrangement. Analysis of variance was carried out on the data using Genstat Statistical package and means were compared using LSD at 5% level of significance (P=.05). Application of cattle manure and inorganic nitrogen fertilizer CAN had no effect or slightly decreased root length and had no effect on the number of branches per plant irrespective of seasons. The application of organic and inorganic fertilizers increased plant height, canopy width and fresh and dry weights depending on the season. The plants planted during the second and drier second season had lower growth and yield attributes compared to those planted during the first season. Of significance was the significant yield increase from multiple harvests with indications of yield improvements from as low as 1.5-4.0 tons/ha to between 15-20 tons/ha. Calcium ammonium nitrate was more effective compared to cattle manure during the dry season compared to the wet season, when cattle manure significantly increased yields (P>.05). The four select local cowpea accessions responded positively to the organic and inorganic fertilizers over seasons and therefore have the capacity to address food security and income generation in marginal parts of Kenya.