Effect of sulphur on growth, productivity, and economics of wheat (Triticum aestivum) and residual soil fertility under aerobic rice (Oryza sativa)–wheat cropping system in Inceptisols

Abstract

A field experiment was conducted during the winter (rabi) seasons of 2010–11 and 2011–12 at New Delhi, to study the direct and residual effect of sulphur (S) application on growth, productivity and economics of wheat (Triticum aestivum L.) grown under aerobic rice (Oryza sativa L.)-wheat cropping sequence. The experiment was laid out in a randomized block design for first aerobic rice and split-plot design for succeeding wheat and second cycle of aerobic rice–wheat system. Five treatments comprising combinations of 2 S sources i.e. gypsum and phosphogypsum and 3 S levels, i.e. 0, 30 and 60 kg S/ha, were taken in aerobic rice. And in succeeding wheat, each main plot was split into 3 sub plots for application of elemental sulphur at 3 levels, i.e. 0, 15, and 30 kg S/ha and replicated thrice. Application of sulphur resulted in increase of growth parameters i.e. plant height, dry matter accumulation, leaf-area index (LAI), chlorophyll content and crop growth rate (CGR) over the control. The yield attributes, viz. effective tillers/m2, spike weight (g) and filled grains/spike were observed highest with 30 kg S/ha, followed by 15 kg S/ha. Averaged across two years, application of 15 and 30 kg S/ha increased the grain yield of wheat by 8.4 and 11.6%, respectively, over no sulphur treatment. Corresponding values for straw yields were 8.9 and 11.4%, respectively. Though highest yields (grain, straw and biological) were obtained with 30 kg S/ha, but significant response was observed only up to 15 kg S/ha. The highest net return was fetched with 30 kg S/ha, but significant response was found only up to 15 kg S/ha. Application of 60 kg S/ha through either of the sources to preceding rice had a significant residual effect on yields and economics of succeeding wheat. Highest status of available N, P and K after wheat harvest was recorded in no sulphur treatment and, in contrast availability of sulphur in soil increased with increasing level of sulphur up to 30 kg/ha.