Passivity of gypsum application on soil pH and its significance on exchangeable calcium, available sulphur and yield of paddy, maize and groundnut under different soil conditions

Abstract

Changes in the pH of acidic, neutral, and alkaline soils in response to various rates and types of gypsum such as slag-based gypsum (SBG) and commercial gypsum (CG), and their effects on soil exchangeable calcium (Ca2+) & available sulphur (S) and yield of different crops were studied in field conditions. Statistical investigation such as linear regression model was used to know the relationship of gypsum application with crop yield revealed that application of SBG and CG was positively and significantly regressed with the yield of paddy, maize and groundnut in all the soils. Significant linear relationship with the pH of acid and neutral soils of paddy have been noticed with application of SBG and CG. Paddy grown in alkaline soil and maize grown in acid and neutral soils had a significant relationship between pH and SBG & CG application. Increased rate of application of SBG as basal and split significantly increased the kernel yield of groundnut. Application of SBG and CG linearly and significantly increased the exchangeable Ca2+ and available S content of soils in which paddy, maize and groundnut were grown. Acid soils responded well in increasing exchangeable Ca2+ and available S compared to other paddy, maize and groundnut soils. Linear relationship was noticed between exchangeable Ca2+ and pH of acid soils paddy, maize and groundnut as influenced by SBG and CG. Whereas, exchangeable Ca2+ content of alkaline soils of paddy also regressed strongly with pH. An increase in available S increased the soil pH of paddy, maize and groundnut, but it was significant with neutral soils of paddy and maize.