LAUSR

ABSTRACT Sulfur (S) availability is a characteristic of conservation tillage. We studied the effects of S on sunflower yield and fatty acid profile under conventional and conservation tillage in silty clay soil of D.I. Khan, Pakistan. Conventional tillage consisted of disk plowing followed by tiller and rotavator, while conservation tillage comprises tiller and disc harrowing. Treatments comprise six sulfur levels (S1 = 0, S2 = 20 kg S ha−1 at sowing, S3 = 10 kg S ha−1 at sowing +10 kg S ha−1 25 days after sowing (DAS), S4 = 40 kg S ha−1 at sowing, S5 = 20 kg S ha−1 at sowing + 20 kg S ha−1 25 DAS, and S6 = 20 kg S ha−1 at sowing + 10 kg S ha−1 25 DAS + 10 kg S ha−1 50 DAS) replicated thrice. After 2 years of experimentation, soil samples were collected (from 0 to 0.30 m depth) for organic matter (OM), total soil N (TSN), and available sulfur analysis. Conservation tillage significantly increased OM, TSN, and S contents in 0–0.30 m soil compared to conventional tillage. Likewise, sunflower plants showed higher achene yield, better fatty acid profile, and net economic returns in conservation tillage than in conventional tillage. Application of 20 kg S ha−1 at sowing and 10 kg S ha−1 at each 25 and 50 DAS recorded significantly higher achene yield, higher oil, and linoleic acid contents; however, oleic and oleic/linoleic ratio did not increase with higher S rates. Conservation tillage was effective in increasing OM, TSN, and available S besides increasing yield and economics in silty clay soil.