Effect of Organic Manures on Soil Physicochemical Properties, Soil Microbial Biomass and Yield of Mustard under Irrigation of Different Residual Sodium Carbonate Waters

Field experiment was conducted to workout the effect of different residual sodium carbonate (RSC) waters and organic manures on physicochemical properties, soil microbial biomass and yield of mustard in loamy sand soil during rabi seasons of 2006–07 and 2007–08. The treatments were: Four levels of RSC waters (2, 6, 9 and 12 mmol L¹) and five levels of organic manures (control, recommended dose of N fertilizer, 12 t FYM ha¹, 5 t poultry manure ha¹ and 4 t vermicompost ha¹). Result revealed that under application of 12 mmol L¹ RSC of irrigation water whereas the bulk density, pH, CEC and ESP increased significantly, saturated hydraulic conductivity, EC and organic carbon of soil at harvest exhibited a significant decreased. The soil biological activity like build-up and losses of microbial biomass C, N and P were reduced significantly, while, turnover rate of microbial biomass increased with all the levels of RSC of irrigation water; difference was not significant among water up to 6 mmol L¹ of RSC. The seed and stover yield of mustard also decreased significantly with increasing levels of RSC. Application of organic manures significantly reduced the saturated hydraulic conductivity; moisture retention at 33 kPa, and 1500 kPa; and available water and organic carbon content of soil. The bulk density, pH, ESP, turnover rate of biomass C, N and P decreased significantly, while CEC of soil at harvest increased significantly with application of 5 t poultry manure ha⁻¹. Significant increase was noted in seed and stover yield of mustard under all the organic manures over control and recommended dose of N fertilizer.