Soil enzyme activities with biomass ashes and phosphorus fertilization to rice–wheat cropping system in the Indo-Gangetic plains of India

Bagasse ash (BA) and rice husk ash (RHA) contain significant quantities of P and many other nutrients. Application of biomass ashes has been shown to improve crop yields and soil properties. The present experiment was conducted to determine the effect of BA and RHA application in combination with different doses of P fertilizer on soil enzyme activities in rice–wheat rotation in the Indo-Gangetic plains of India. Both BA and RHA significantly increased the dehydrogenase, alkaline phosphatase and phytase activities as compared to no ash application in the 0–0.15 m soil layer. Activities of these enzymes also increased with P fertilization. Biomass ashes and P fertilizers showed little effect on enzymatic activities in the 0.15–0.30 m soil layer. Application of biomass ashes and P fertilization significantly increased Olsen-P and organic carbon content in soil over control. Enzyme activities were significantly and positively correlated with Olsen-P, organic carbon content and wheat grain yield. This study suggests that soil quality can be improved by applying biomass ashes and P fertilization on a loamy sand soil under rice–wheat system.