Nitrogen Fractions, Microbial Population and Maize Yield as Affected by Type of Animal Manure Applied in Agricultural and Wetland Soils at Abeokuta and Bodako farms, Ogun State, Nigeria

Abstract

Soil differs in nitrogen (N) fractions mineralized and available for uptake by crops, which are facilitated amongst others factors by the microbial nature of the soil. Hence the objective of this paper was to investigate the nitrogen fractions, microbial population and maize yield as affected by type of animal manure applied in agricultural and wetland soils at Abeokuta and Bodako farms, Ogun State, Nigeria. Poultry manure and cowdung at 65kgNha⁻¹, and no amendment/control were applied to the experimental fields of agricultural soil (Typic Tropudalfs) and wetland soil (Aqualfs). Data obtained show that there were variability among the N fractions irrespective of sampling time. The N fractions were abundance at postharvest as compared to at 2 Weeks after application (WAA). Soil Ammonium-N and Nitrate-N immobilize by 60.3% – 65.5% and 59.2% - 69.2%, respectively. Total N and Organic-N mineralize by 49.3% - 76% and 42.6 - 45.8%, respectively. Consequently, a ratio of isolated bacteria to fungal (3:1) was identified. Where estimated population counts (Epc) were higher in harvested soils [115.5 x 10^-6 Colony Forming Unit per gram (CFU/g) soil bacteria, and 103.4 x 10^-6 CFU/g soil fungi] of applied Agricultural soil/cowdung. It was different at 2 WAA, where wetland soil/cowdung applied was 108.8 x 10^-6 CFU/g soil bacteria, and Agricultural soil/cowdung applied 89.2 x 10^-6 CFU/g soil fungi. Evidently, the build-up of soil organic carbon (SOC) was significantly low in wetland soil/Aqualfs (27%). All fractions, however, had strong positive relationship with SOC. Plant tissue N (1.21%), dry matter yield (0.034t/ha) and grain yield (2.37t/ha) were significantly high and productive in Agricultural soil (Typic Tropudalfs) due to higher Epc. Therefore, N mineralization and its uptake can be improved through increased activities of soil microbes for optimum crop yield.