Authors: Amusan, O. A., Adetunji, M. T. and Azeeez J. O.
Amusan, Adetunki and Azeez NJSS/21 (2) 2011
Abstract
This study was carried out on a tropical alfisol for two years to investigate the effect of a legume based integrated nutrient management system on the soil status of nitrogen and phosphorus. The treatments consisted of two rates of poultry manure (0 and 5 t ha), three rates of N fertilizer (0,50
and 100 kg N ha applied as urea), three rates of P fertilize (0, 3 and 60kg P ha’ applied as single superphosphate) and two soybean treatments (with or without legume residue) arranged as a factional experiment using randomized complete block design (RCHD) with three replicates. Soil samples were collected, processed and analyzed before planting and after harvests each year for N and P and other soil properties. Results show that he impact of legume on Soil P was the least as it accounted for mere, 4.0% and 0.8% increase in soil P in 2004 and 2005 respectively. Manure x P fertilizer interactions produce the most significant effect on Soil P as it accounted for 47.2% increase in Soil P at 5 t ha and 60 kg P ha level of combination over control. Of all the interactions studied on Soil N only the LxMxN and MxN interactions were significant. In 2005, MxN interaction increased Soil N by 110 .5% while LxMx”l interaction increased Soil N in 2004 by 166% Manure, fertilizer N and fertilizer P were found to be controlling factors in Soil N and soil P. Soybean on its own had little or no effect on Soil N and P.