Effect of mineralized nitrogen through decomposition of plant residues on the uptake of maize (Zea mays L.) in sudan savannah ecological zone of Nigeria

Abstract

A field experiment was designed to determine the effect of mineralized nitrogen (N) through the decomposition of leafy biomass of agroforestry tree species as residues to underscore its uptake by maize under Sudan savannah conditions. The experiment was laid out as 3 x 4 x 2 factorial in a split-split plot design with three replicates for two cropping seasons. The factors considered include: control, biomass species (Albizia lebbeck and Parkia biglobosa) as main plots, four levels of nitrogen fertilizer (0, 40, 80, 120 kg N ha-1) as sub-plots, and two maize varieties (DMR-ESR-7 and 2009 EVAT) as sub-sub plots. Data were analysed using Analysis of Variance (ANOVA). Chemical composition of A. lebbeck biomass had higher average contents of N (32.4 g kg-1) and C (186.4 g kg-1) and lower average C: N ratio (57.5) than P. biglobosa and this affected their decomposition rates, hence, A. lebbeck decomposed faster than P. biglobosa. 56 % of N in the litter bags were released within the first 2 weeks of biomass incorporation and progressively increased up to 10 weeks after planting (WAP). Total N uptake by maize was lowest (2.8 kg N ha-1) in P. biglobosa and was highest (8.6 kg N ha-1) in A. lebbeck amended plots. It is then concluded that total N uptake by maize crop increased rapidly between 4-6 WAP, and the impact was obvious in plots amended with A. lebbeck biomass than in P. biglobosa plots during the two cropping seasons.