Microbial biomass carbon and microbial activities of soils receiving chemical fertilizers and organic amendments

Effect of chemical fertilizers and organic amendments on soil chemical and microbiological properties were studied in soils receiving these amendments over a period of 3 years under tropical conditions. Soil organic C and total N increased in treatments receiving a combination of organic amendments and different doses of chemical fertilizers compared to soils receiving chemical fertilizers alone. Mineral N and available P in the soil were greater with the integrated use of chemical fertilizers and organic inputs. Microbial biomass C increased significantly with the combined application of chemical fertilizers and organic amendments, in comparison to soils receiving chemical fertilizers alone. Dehydrogenase and alkaline phosphatase activities also increased with the application of farmyard manure and Sesbania aculeata green manure. The results indicated that there is improvement in soil organic matter, microbial activities and crop yields due to the use of chemical fertilizers along with organic manures. Such positive effects of organic inputs can help in maintaining organic matter level and sustain good crop yields over a period of time without deteriorating soil health.