Influence of organic inputs with mineral fertilizer on maize yield and soil microbial biomass dynamics in different seasons in a tropical acrisol

Introduction The practice of co-applying chemical fertilizers (CF) with organic inputs (OIs) as a soil amendment is still low in Ghana, although it has the potential to improve crop yield and soil productivity. Objectives In a two-year study, we evaluated the effects of co-applying contrasting OIs with and without CF on maize yield and soil chemical and microbial composition. Methods Aboveground biomasses of Centrosema pubescens (CEN), Pueraria phaseoloides (PUE), and Zea mays (MZE) were amended to an acrisol at 4 t ha−1 season−1. The combined treatments (CEN+, PUE+, and MZE+) were fertilized with basal NPK 15:15:15 at 40 kg N ha−1, followed by topdressing with [(NH4)2SO4] at 50 kg N ha−1. Sole OI inputs (CEN, PUE, and MZE) did not receive any CF inputs. The controls (CON− and CON+) received 0 and 90 kg N ha−1 season−1. Results The results showed that either sole OIs except for MZE or its combination with CF improved grain yield compared to the CON. Grain yield ranged from 2.1 t ha−1 to 2.6 t ha−1 in the first season versus 0.8 t ha−1 to 1.7 t ha−1 in the second. The MZE+ and CEN+ treatments showed the highest mean grain yields and were similar to CON+. Although CF addition to OIs improved grain yield in all treatments, negative interaction was observed for CEN and PUE as opposed to a positive interaction in the MZE treatment. Co-application of CF with OIs on dissolved organic carbon and nitrogen (DOC) and (EON) dynamics depended on seasonal soil moisture and sampling time. Moreover, co-application of CF with OIs enhanced microbial biomass in CEN but showed minimal and suppressive effects on MZE and PUE amendments, respectively. Conclusion Overall, the increased grain yield in MZE+, CEN+ and CON+ was attributable primarily to the CF addition. Thus, long term evaluations are recommended for sustainable utilization of MZE and CEN given their minimal responses in the short term in the presence of CFs.Peer Reviewe