ABSTRACT
Sulfur (S) has long been recognized as an essential element for plant growth and development and is classified as a macronutrient. Crop responses to applied sulfur have been reported in a wide range of soils in many parts of the world (Blair et al., 1979; Follett et al., 1981; Tisdale et al., 1985; Tisdale et al., 1986; Malavolta et al., 1987; Schnug and Haneklaus, 1998; Brady and Weil, 2002). Sulfur deficiency has been reported in rice from various countries such as Indonesia, Brazil, India, Bangladesh, and Thailand (De Datta, 1981). Yasmin et al. (2007) reported that rice crops throughout the world are becoming increasingly affected by sulfur deficiency as the use of S-free fertilizers increases. Ismunadji (1985) reported higher rice grain yields with sulfur application under flooded as opposed to nonflooded conditions. Boem et al. (2007) reported yield increase of soybean with S application in the Argentinean pampas. Solberg et al. (2007) reported that in the Canadian prairie provinces, there are approximately 4 million ha of cultivated soils deficient in plant-available sulfur, and additional large areas are estimated to be potentially deficient. Wells et al. (1993) reported sulfur deficiency in rice in Arkansas, United States. In addition, in the United States, deficiency of S has been reported in the Southeast, the Northwest, California, and the Great Plains (Brady and Weil, 2002). Tisdale et al. (1986) reported that sulfur deficiency has been observed in crop plants in 22 African countries. These authors also reported that the majority of the reported S deficiencies in the African continent are in areas south of the Sahara on highly weathered soils that receive over 600 mm minimum rainfall per year. Similarly, sulfur deficiency has been reported in Asia, Australia and New Zealand, Europe, Central and South America, and the West Indies (Tisdale et al., 1986). The fungicidal effect of foliar-applied elemental S has been exploited since the end of the 19th century. In comparison, the significance of soil-applied S, independent of the form of S, for disease resistance only became evident a century later, when macroscopic S deficiency developed into a widespread nutrient disorder. The main reason was the drastic decrease of SO2 emissions in western Europe after clean air legislation came into force (Haneklaus et al., 2007).
