Comparative Evaluation of Poultry Manure and NPK Fertilizer on Soil Physical and Chemical Properties, Leaf Nutrient Concentrations, Growth and Yield of Yam (Dioscorea rotundata Poir) in Southwestern Nigeria

Abstract

Field experiments were conducted in 2006, 2007 and 2008 cropping seasons at the Teaching and Research Farm of Rufus Giwa Polytechnic, Owo (7°12′N, 5°35′E) in the forst-savanna transition zone of southwest Nigeria to evaluate the effects of poultry manure and NPK fertilizer on soil physical and chemical properties, leaf nutrient concentrations, growth and yield of yam. The treatments were no fertilizer/manure (control), 400 kg ha-1 NPK fertilizer, 20 t ha-1 poultry manure and 200 kg ha-1 NPK fertilizer+10 t ha-1 poultry manure, laid out in a randomized complete block design with three replications. Application of poultry manure, poultry manure+NPK fertilizer significantly reduced soil bulk density, temperature and increased soil water content and porosity, whereas application of NPK fertilizer alone did not improve soil physical properties. Compared with the control, application of poultry manure, NPK fertilizer and poultry manure+NPK fertilizer significantly increased Soil Organic Carbon, N, P, K, Ca and Mg as well as leaf N, P, K, Ca and Mg concentrations. Poultry manure tended to improve soil pH, soil Organic Carbon, N, K, Ca and Mg concentrations compared with NPK fertilizer and gave higher leaf nutrient concentrations, growth and tuber weight than NPK fertilizer. The highest leaf area, tuber length, tuber girth and tuber weight were obtained with combined application of sub-optimal rates of poultry manure+NPK fertilizer in 2006, 2007 and 2008. Compared with the control, the use of NPK fertilizer, poultry manure and poultry manure+NPK fertilizer increased tuber weight by 53, 86 and 131%, respectively. Therefore, the use of poultry manure+NPK fertilizer is recommended for soil conservation and yam production simultaneously.