Effect of different sulfur levels from various sources on brassica napus growth and soil sulfur fractions

A two year field study was conducted at two different locations in northern rainfed punjab,pakistan to assess the effect of different rates of sulfur application from various sources on soil sulfur fractions and growth of brassica napus. the treatments included three sulfur sources i. e.,single super phosphate,ammonium sulfate and gypsum each applied at five different rates (0,10,20,30 and 40 kg s ha -1). sulfur application had a significant positive effect on the growth and yield parameters of brassica napus. among the sulfur sources ammonium sulfate resulted in maximum increase in plant growth and yield parameters,followed by single super phosphate. sulfur content and uptake by crop plants was significantly higher with ammonium sulfate application as compared to other two sulfur sources. sulfur application also exerted a significant positive effect on different s fractions in the soils. on an average,18.0% of the applied sulfur got incorporated into cacl 2- extractable sulfur fraction,while 15.6% and 35.5% entered into adsorbed and organic sulfur fractions in the soils,respectively. the value cost ratio increased significantly by sulfur application up to 30 kg ha -1. among sulfur sources,ammonium sulfate performed best giving the highest net return.