Slag-Based Gypsum as a Source of Sulphur, Calcium and Silicon and Its Effect on Soil Fertility and Yield and Quality of Groundnut in Southern India

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.