Experiments were conducted at three locations in 1990 and two locations in 1991 to evaluate the response of cotton (Gossypium hirsutum L. cv. Deltapine 50) to sulfur (S) applications on Routon-Dundee-Crevasse soil complex and develop soil and plant diagnostic criterion to improve the accuracy of S fertilizer recommendations. The soils in the experimental area were primarily Routon and Dundee sandy loams. Soil S rates of 0 - and 20-lb-SO₃-S/acre and a foliar rate of 4-lb-SO₃-S/acre were evaluated. The foliar treatment was applied only when S deficiency symptoms appeared.

Excessive spring and winter rainfall, especially in 1991, was conducive to the development of S deficiency. Slight S deficiency symptoms appeared at one location in 1990 and at each location in 1991. Even though conditions were conducive to the development of S deficiency, cotton yield was not increased in either yearby the application of S on these sandy soils.

The SO₃-S content of the petioles was well correlated with soil-applied S throughout much of the growing season each year. The NO₃-N/SO₃-S ratio decreased as the growing season progressed.

This study suggest that the probability of a cotton response to applied S on the more typical cotton soils, i.e. Routon and Dundee sandy loams, may be low. A S response may be more likely in certain years on soils with deep sand profiles, i.e., Crevasse loamy sand.