ABSTRACT

A field study was conducted on an Ultisol at the National Root Crops Research Institute, Umudike in year 2000 to determine the effects of' manure (poultry manure) at 0, 10, 20 and 30 tons ha 4and inorganic fertilizer (NPK 20-10-10) at 0, 125, 250 and 500 kg ha1 on soil properties and maize performance. The experiment was a factorial in a randomized complete block design (RCBD) with three replications. Results showed that the treatments had no significant (P>0.05) effect on organic matter, pH and texture of the soil. At the surface 0-10 cm soil depth, there was a significant manure x inorganic fertilizer interaction on total N, while available P. exchangeable K, exchangeable Mg and ECEC were influenced by poultry manure alone and exchangeable Na increased with increasing NIK fertilizer rates. Similarly, available P and exchangeable K at the 10-20 cm soil depth were improved by the interaction of manure and inorganic fertilizer rates. However, the levels of these soil parameters, except available P. were generally low suggesting further supplemental treatments for the sustenance ot'a subsequent crop. Uptake of N, Ca, Mg, Fe and Mn by maize plant was enhanced by a joint application of poultry manure and NPK fertilizer whereas poultry manure alone iniproved the uptake of P, K and Cu with 10 tons ha' manure rate appearing to be the optimum for the maximum uptake of most nutrients. Though manure x inorganic fertilizer interaction was not significant for maize grain yield, it significantly increased plant height, total dry matter and number of' leaves per plant. The highest maize height of 227.0 cm and number of' leaves per plant of 15.0 were obtained with 30 tons ha" poultry manure plus 125 kg ha" NPK fertilizer mixture while the highest dry matter of 3 15.19 g per plant vis produced with 30 tons ha" poultry manure and 250 kg ha" NPK fertilizer mixture. Application of' poultry manure alone increased maize grain xiv yield from 1.51 tons ha' at 0 tons ha' manure rate to 4.45 tons ha' at 30 tons ha1 manure rate. Similarly, maize grain yield increased with increasing NPK fertilizer rates from 3.25 tons ha' at 0 kg hat to 3.77 tons ha' at 500 kg ha' NPK fertilizer rate. Of all the plant growth parameters, only total dry matter increased with increasing rates of nutrient uptake, whereas only plant height and number of leaves per plant increased as grain yield increased (r = 0.90; P<0.001) and (r = 0.83: P0 001), respectively. For maize production at Umudike ecological zone, either 10 tons ha1 poultry manure plus 0 kg ha' NPK fertilizer mixture or 250 kg ha' NPK (20:10:10) fertilizer rate is recommended.