Sulphate sorption behaviour of a kandic paleustalf after long-term cropping with different fertilizer and farmyard manure inputs

Sulphate sorption behaviour of a Kandic Paleustalf was studied in relation to continuous addition of S with NPK or in combination with NPK plus FYM over the last decade under finger millet-maize-fodder cowpea rotation. Soil samples from the six differentially S fertilized plots differed widely in their sulphate sorption behaviour consistent with variations in apparent S balance (addition-crop removal). The extent of sulphate sorption was strikingly higher in soils that received 100% NPK without S as compared to adjacent fallow plot. Consequently in plots that received S with NPK, the sulphate sorption progressively decreased with increased rates of fertilizer S. Continuous addition of farmyard manure reduced the sulphate sorption by soil in 100% NPK (+S)+FYM plot as compared to 100% NPK(+S) alone treatment. The sulphate sorption maxima (b) was highest for 100% NPK(−S) treatment and decreased with increasing rates of S fertilization.