OPTIMUM RETURNS IN GROUNDNUT PRODUCTION UNDER THE INFLUENCE OF POULTRY MANURE RATES AT SAMARU IN THE NORTHERN GUINEA SAVANNAH OF NIGERIA

Groundnut plays an important role in the diets of rural populations, livestock feeding and soil fertility improvements. Poor soil fertility, availability and affordability of inorganic fertilizer have been identified as major constraints to groundnut production. These constraints can be addressed by the use of poultry manure, but there is the need to determine the optimum level of poultry manure that will give the best yield. To achieve this objective, field trials were conducted at Teaching and Research farm of Samaru College of Agriculture, Ahmadu Bello University Zaria located in the northern Guinea savannah ecological zone of Nigeria during the 2012 and 2013 rainy seasons. The treatments consisted of three levels of poultry manure (0, 1.5 and 3 tonnes ha-1) and three varieties of groundnut (SAMNUT 11, SAMNUT 22 and SAMNUT 23).The treatments were laid out in a split- plot design with poultry manure occupying the main plot while the variety was allocated to the subplots. The data collected were subjected to analysis of variance, where significant differences existed, the Duncan multiple range tests was used to separate the means. In order to determine optimum yield as a result of poultry manure application rates, the data were subjected to regression analysis. Both the yield data and the results obtained from regression analysis were subjected to economic analysis using the gross margin and the cost benefit analysis. The yield data obtained from the trials showed that application of 1.5 tonnes ha-1 resulted to highest pod yield (2709 kg ha-1, 2425 kg ha-1 and 2537 kg ha-1in 2012, 2013 and the combined). Using the regression analysis, the optimum rates of 1.70 tonnes ha-1, 1.95tonnes ha-1 and 1.83 tonnes ha-1 were obtained in 2012, 2013 and their combined to give a yield of 2725 kg, 2472 kg and 2567 kg ha-1,respectively. The economic evaluation showed that application of 1.5 tonnes ha-1 of poultry manure gave the highest gross margin (₦241,405, ₦217,925 and ₦226,659 in 2012, 2013 and combined) and cost- benefit ratio (₦3.40, ₦3.06 and ₦3.19 in 2012, 2013 and combined) while the optimum rates of 1.70 tonnes ha-1obtained from the regression analysis had a gross margin of ₦199, 500, ₦171,700 and ₦182,400 in 2012, 2013 and combined, respectively. The cost benefit ratio of ₦ 2.73, ₦2.27 and ₦2.46 were obtained in 2012, 2013 and combined, respectively. It can be concluded that the application of 1.5 tonnes ha-1 gave higher yield and appeared more profitable to farmers in the study area, hence, recommended for use.