Slag-based gypsum (SBG) is a unique synthetic gypsum which is alkaline in nature, besides calcium (Ca) and sulphur (S); it contains appreciable amounts of iron (Fe), silicon (Si), phosphorus (P) and zinc (Zn). In this study, we evaluated the efficacy of SBG as a source of S, Ca and Si for groundnut in comparison with natural gypsum (NG). The effect of different levels and time of application of SBG on soil fertility and yield and quality of groundnut were also studied. Field experiments were conducted with five treatments which includes two levels of SBG (500 and 625 kg ha −1) applied as basal and basal + split and one level of NG (500 kg ha −1) applied as basal. Basal and basal + split applications of SBG significantly increased the pod and haulm yield of groundnut, pH, electrical conductivity and plant-available nutrients in post-harvest soil. However, N:S ratio, kernel and protein yield and oil content did not vary with SBG application. Applied S, Ca and Si as SBG and their uptake were positively correlated with plant-available S, Ca and Si and pod, oil and protein yield of groundnut, respectively. Basal and basal + split applications of SBG resulted in a similar effect on soil fertility and yield and quality of groundnut. Findings from this study show that SBG can be a potential alternative for NG as a source of S, Ca and Si for groundnut production. Among the treatments, basal and basal + split applications of 625 kg SBG ha −1 substantially improved the fertility of soils and yield and quality of groundnut.

Yellow gypsum (YG), a synthetic product from Linz-Donawitz slag containing high iron (Fe) (5.41%), zinc (Zn) (0.37%) and silicon (Si) (3.41%) can be used as a source of these nutrients along with calcium (Ca) and sulphur (S) for groundnut production. Three field experiments were conducted to know the effect of different rates (500 and 625 kg YG ha−1) and time of application (basal alone and basal + split) of YG on growth, yield and economic returns of groundnut, and micronutrient and Si availability and their uptake in comparison with basal application of 500 kg natural gypsum (NG) ha−1. Basal alone and basal + split application of YG significantly increased the growth, yield and economic returns of groundnut. Further, it increased the soil pH, availability of micronutrients, Si and their uptake by haulm and kernel of groundnut over NG. Irrespective of the location, YG application recorded higher plant available nutrient (PAN) coefficient of micronutrients, while NG application recorded higher PAN recovery coefficient of Si. Basal + split application of YG resulted in better growth and yield of groundnut than basal application of YG. In conclusion, YG can be a potential alternative for NG as a source of Fe, Zn and Si along with Ca and S for groundnut production.

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.