Yield and sulphur nutrition of paddy-wheat cropping system as influenced by sources and levels of sulphur fertilization

A field experiment was conducted with a Typic Haplustept, sandy loam sulphur deficient soil to study the effect of S fertilization on yield and S nutrition of paddy-wheat cropping system. Sulphur was applied @ 0, 20, 40 and 60 kg S/ha through each gypsum and bentonite S-pastilles (S-90) to the first crop only i. e. paddy. Direct application of different levels of S through gypsum as well as S-90 did not produce a significant effect on grain and straw yield of paddy. However, its residual effect produced a significant response of 2.9 and 3.6 q/ha in grain yield of wheat when 40 and 60 kg S/ha were applied through gypsum and S-90, respectively. The non-significant effects of S application on grain and straw yield of paddy may be due to the contribution of S through irrigation water (3 mg/1). Total S removal by paddy increased significantly over control when 40 and 60 kg S/ha was applied as gypsum. But total S uptake by paddy was not affected significantly when S-90 was the source of sulphur. Total S uptake by wheat increased significantly over control at each level of applied S irrespective of the source of S. An incubation study was conducted with the same soil as used in field experiment to study the release of S from gypsum, single superphosphate and bentonite S-pastilles (S-90) applied @ 60 kg S/ha from each source. A highest mean increase in available S in soil was observed when SSP was the source. A significant negative linear coefficient of correlation (r= -0.752**) between soil pH and S extracted in soil was also observed.