Source and mode of sulphur application on groundnut productivity

Abstract

The effectiveness of 20 kg/ha sulphur (S) of the S‐containing compounds iron sulphate (FeSO₄), gypsum, phosphogypsum, elemental S, and pyrite on groundnut (Arachis hypogaea L.) productivity was determined for plants grown on calcareous soil in the field. Plants grown with S compared to those without S had increased plant height, number of flowers, nodule numbers and weight, higher dry matter, seed, haulm (leaves and stems), and oil yields; higher tissue concentrations of nitrogen (N), phosphorus (P), S, iron (Fe), and zinc (Zn); and higher total uptake of mineral nutrients. Elemental S, pyrite, and FeSO₄ were more effective than gypsum and phosphogypsum, with FeSO₄ being the most effective source of S for improving plant growth traits, yield, and nutrient uptake. The most effective method of FeSO₄ application was half to the soil at planting time (basal) followed by the remainder in three equal foliar sprays at 30,50, and 70 days after plant emergence (DAE). Pyrite and elemental S were most effective when applied to the soil only, half as a basal soil dressing, and the remainder in two equal doses at 25 and 50 DAE. Plant concentrations of S, P, and potassium (K) were similar for each source of S, but elemental S, pyrite, and FeSO₄ enhanced N, Fe, manganese (Mn), and Zn uptake. Gypsum and phosphogypsum enhanced calcium (Ca) uptake. Elemental S and FeSCM provided similar results when half was applied to the soil followed by three equal foliar sprays. The best results from pyrite, gypsum, and phosphogypsum were obtained when soil applied.