Relative efficiency of sulphur sources at varying rate in aerobic rice (Oryza sativa)-wheat (Triticum aestivum) cropping system

Afield experiment was conducted during 2010-11 and 2011-12 at the research farm of Indian Agricultural Research Institute, New Delhi to study the effect of sulphur fertilization on productivity, economics and nutrient use efficiencies of aerobic rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system.The results revealed that aerobic rice and wheat both responded to sulphur significantly. Sulphur fertilization in aerobic rice through gypsum @ 30 and 60 kg S/ha and phosphogypsum @ 30 and 60 kg S/ha increased the rice equivalent yield of system by 7.8, 10.6, 7.0 and 9.8 %, respectively, over control (no sulphur in rice). The values for per cent increase in rice equivalent yield of systems was 8.4 and 11.6% for 15 and 30 kg S/ha, respectively, when applied to wheat over the control treatment in wheat. Significant response of S applied to rice was found only up to 30 kg S/ha, except 30 kg S/ha applied through phosphogypsum during 2010-11. In wheat, significant response of S was found only up to 15 kg S/ha during second year. During first year of rice-wheat cropping system, economic optimum dose (EOD) of sulphur was 30 kg S/ha through gypsum to rice and 15 kg elemental S/ha to succeeding wheat, while during second year only 30 kg S/ha through either of the sources to rice was found sufficient for both the crops. The apparent sulphur balances and available sulphur in soil were more in higher doses of S application to both the crops. The partial factor productivity, agronomic efficiency and crop recovery of applied S were highest with application of 30 kg S/ha in aerobic rice and 15 kg S/ha in succeeding wheat during both the years of experimentation.