Soil fertility, microbial dynamics and mustard yield potential mediated by addition of organic amendments under sodic irrigation water

ABSTRACT Use of saline-sodic irrigation water degrades soil health and reduced mustard yield, particularly in India’s low-rainfall regions. This research was conducted to assess the effect of sodic water and nitrogen sources on soil organic carbon (SOC), microbial biomass, soil enzymatic activities, and interaction effects on mustard seed yield. The experiment was laid out in split-plot design comprising four levels of sodium adsorption ratio (SAR) of water (6, 10, 20, and 30) and six nitrogen sources [(control, 125% recommended dose of nitrogen (RDN) through urea, 75% RDN+50% RDN through farm yard manure (FYM), 75% RDN through urea+50% RDN through vermicompost (VC), 50% RDN through urea+75% RDN through FYM, 50% RDN through urea+75% RDN through VC]. The use of high SAR irrigation water caused a significant reduction in soil fertility and microbial parameters. The combined use of chemical fertilizers, FYM, and vermicompost significantly increased microbial activities (64.9% SMB-C), SOC (23.5%), soil enzyme activity (dehydrogenase and alkaline phosphates), and mustard seed yield (49%). The use of 50% RDN via urea+75% RDN via VC was suggested as a better technology for minimizing the adverse effect of high SAR water on crop yield.