Sulphur forms and maize yield under long term tillage practices and cropping systems

Sulphur apart from being an essential element for plant growth is also a structural constituent of many coenzymes and secondary plant products or acts as a functional group directly involved in metabolic reactions and hence the factors promoting its mineralization in soil and further acquisition in plants are an important area of study. In the present study a modest initiative has been undertaken to study the effect of conservation practices on different forms of sulphur, maize yield and S uptake. For this, surface soil samples from a field experiment with three tillage practices as main plots and six maize-based cropping systems as sub-plots replicated thrice were analysed for five consecutive years. After five years of study, it was observed that all the forms of sulphur were higher under zero tillage and soybean-maize cropping system except adsorbed sulphur which was higher under conventional and maize-maize cropping system. Available Sulphur, Water soluble sulphur, Heat Soluble Sulphur, Adsorbed Sulphur and Organic sulphur was on an average 3.99, 3.57, 11.38, 3.67 and 64.06%, respectively of Total Sulphur. Sulphur availability index increased by 6.40% as result of continuous adoption of zero tillage. Higher grain yield of was recorded under zero tillage (4.88 t ha(-1)) and maize-chickpea (5.42 t ha(-1)) system; while total S uptake was highest under zero tillage and maize-mustard system (29.65 and 31.74 kg ha(-1), respectively). Water soluble sulphur was found to have significantly higher and positive correlation with maize grain yield (r = 0.910**) while heat soluble sulphur with total S uptake (r = 0.896**); while adsorbed sulphur recorded a negative correlation with yield and uptake (r = - 0.520** and r = - 0.316). Conservation practices had substantial impact on S availability, yield and S uptake by the maize crop.