Evaluation of Agronomic Performance of Maize ( Zea m ays L. ) under Different Rates of Poultry Manure Application in an Ultisol of Obubra, Cross River State, Nigeria

Field studies were conducted at the Teaching and Research farm of the Cross River University of Technology, Obubra Campus, Nigeria, during the 2005 and 2006 cropping seasons to determine the agronomic performance of maize under different rates of poultry manure (PM) application. Ten rates of PM treatments consisting of 0, 4, 6, 8, 10, 12, 14, 16, 18, and 20 t/ha were used in this study. The treatments were laid out in a randomized complete block design with three replica- tions. PM application significantly improved maize vegetative growth, biomass, yield components and grain yield. The use of 20 t/ha PM gave the highest maize plant height, stem diameter and number of leaves per plant; while the best 1000-seed weights of 273.5 and 270.7 g, as well as grain yields of 2.78 and 2.89 t/ha were obtained with the application of 18 t/ha PM in 2005 and 2006 cropping seasons, respectively. Moreover, all the evaluated traits were strongly positively correlated with each other (P < 0.0001). Our results indicated that while high rates of PM linearly improved growth attributes up to the highest rate of PM treatment (20 t/ ha), a dose of 18 t/ha applied two weeks before planting was best for maize production in the study area.