A field study, conducted at the National Root Crops Research Institute, Umudike, research farm, evaluated changes in some properties of a degraded Ultisol and nutrient uptake in a maize cropping system amended with four rates each of poultry manure (0, 10, 20 and 30 t ha-1) and NPK 20:10:10 fertilizer (0, 125, 250 and 500 kg ha-1). The experiment was a 4 x 4 factorial in a randomized complete block design (RCBD) with three replications. Results showed that application of fertilizer alone did not significantly improve the uptake of the macro and micro nutrients by the maize crop. However, there existed a significant M x F interaction for the uptake of N, Ca, Mg, Fe and Mn whereas application of manure alone significantly improved P, K, Cu and Mn uptake by the maize crop compared to the control. Though varying rates of the manure alone or in combinations with fertilizer gave the highest uptake of some of the nutrients, 10 t ha-1 manure was found to have maximally influenced uptake of most nutrients. Similarly, though soil pH, OM and EA were not significantly changed by both the manure and fertilizer application, total soil N at the upper (0-10 cm) and, available P and exchangeable K at the lower (10-20 cm) topsoil depths, respectively, were significantly influenced by M x F interactions. The result also showed that soil available P, exchangeable K, Ca and Mg as well as ECEC were significantly improved by manure application alone in both the upper and topsoil with 30 t ha-1 having been found to have maximally improved most of the assessed soil properties. It was concluded that while 30 t ha-1 manure could be regarded as a technical optimum for soil property improvement, 10 t ha-1 manure was the optimum application rate for maximum crop nutrient uptake which implies heavy crop nutrient removals or sequestration in the plant biomass which could be recycled for soil fertility regeneration and enhanced performance of subsequent crop(s). Keywords: Poultry manure, NPK fertilizer, Ultisol, maize and nutrient uptake.
Keywords: Poultry manure, NPK fertilizer, Organo-mineral fertilization, Ultisol, maize and nutrient uptake