Effect of organics, biofertilizers and crop residue application on soil microbial activity in rice – wheat and rice-wheat mungbean cropping systems in the Indo-Gangetic plains

The aim of this study was to investigate the response of soil microbial parameters to nutrient management practices involving organic amendments, farmyard manure (FYM), vermicompost (VC), crop residues (CR) and biofertilizers (BF) in rice–wheat and rice–wheat–mung bean cropping system of the IndoGangetic Plains, India. Soil microbial biomass C (Cmic), basal respiration, ergosterol, glomalin, soil enzymes (glucosidases, phosphatases and dehydrogenases), FDA activity, organic carbon (Corg), Cmic-to-Corg ratio and metabolic quotient (qCO2) were estimated in soil samples collected at 0–15 cm depth. The highest Corg (0.64%) and Cmic (103.8 μg g−1) soil levels occurred in the treatment receiving a combination of VC, CR and BF. Soil respiration, Corg and Cmic-to-Corg ratio were significantly enhanced by the input of CR to plots receiving FYM and VC. The qCO2 was the highest in plots receiving a combination of FYM, CR and BF followed by control (no nutrient input) and least in plots receiving a combination of VC, crop residue and biofertilizer. These results indicate that the organic practices involving VC, CR and BF improved soil microbial characteristics and Corg in rice–wheat systems. *Corresponding author: Geeta Singh, Division of Microbiology, Indian Agricultural Research Institute, New Delhi 110012, India E-mail: [email protected]