Investigating the Effect of Different Rates of Chicken Manure on the Growth, Yield and Profitability of Cowpea (Vigna Unguiculata L. Walp) Under Rain Fed Condition in the Upland Soils of Njala, Southern Sierra Leone

This study investigated the effects of different rates of chicken manure on the growth, yield and yield attributes of cowpea at the School of Agriculture Experimental Site, Njala University during the second season of 2014. A total of six treatments comprising two released Cowpea varieties from the Njala Agricultural Research Centre (NARC) and three chicken manure levels (0, 4 and 8 t. ha-1) were established in split plot design with three replicates. Results revealed that plant height, stem diameter, chlorophyll content, number of fully matured leaves and leaf area significantly increased with time and increasing chicken manure (CM) rate. Variety TVu1190 produced higher plant height, larger leaf area, larger stem diameter and higher yield (2.78 t. ha-1) than IT86D-721. Chicken manure application significantly decreased mean days to 50% flowering, whereas pod and kernel sizes, 1000 g grain weight and yields were significantly enhanced. Application of CM at 8 t. ha-1 produced significantly the heaviest grain weight of 160.17 g, whilst the 0 t. ha-1 had the least (141.83 g). Similarly, the 8 t. ha-1 (3.28 t. ha-1) CM rate had the highest yield followed by 4 t. ha-1 (3.09 t. ha-1) and lowest in 0 t. ha-1 (1.13 t. ha-1). It is most profitable to grow cowpea under 4 t. ha-1 CM point application production system especially for variety IT86D-721. Results suggest that optimum application and adequate supply of plant nutrient from chicken manure is important for the success of conservation and sustainable farming systems. Findings in this study could be utilized in improving efficiency of Nitrogen use in crop management rotation systems.