Effect of Organic and Mineral Fertilizer Inputs on Soil and Maize Grain Yield in an Acid Ultisol in Abakaliki-South Eastern Nigeria

In sustainable agricultural systems, recycling of nutrients is a major component of nutrient management. We conducted an experiment in Abakaliki South Eastern Nigeria in 2007 to investigate the effects of organic amendments (poultry droppings (PD), burnt rice husk dust, (BRHD), Unburnt rice husk dust (UBRHD) and inorganic fertilizer (NPK) on soil properties and their residual effect tested in 2008. Additions of amendments failed to significantly (P< 0.05) improve micro-aggregates (measured as dispersion ratio, DR) but significantly decreased bulk density, increased total porosity and macro-aggregate stability (measured as water stable aggregates WSA > 0.5mm). Similarly, significant improvements were observed in soil total N (%), OC (%), avail P and CEC (Cmol /kg). The highest relative yields of 2.10 and 1.23 mgha in the first and second seasons, 1 were obtained in PD and UBRHD-amended plots, respectively. Results of the study also show significantly higher maize yield and improved soil properties in UBRHD and BRHD in the second season compared to PD and NPK indicating longer residual effect.Maize grain yield correlated positively with soil organic carbon, CEC, aggregate stability and bulk density indicating that these parameters contributed to final grain yield.Results of the study showed that organic and inorganic fertilizers are effective in restoring the productivity of degraded soils.