SECTION I 

 INTRODUCTION 



In 19 71, Beaton et al. made the following statement concerning the 

 S status of Florida soils: 



Sulphur fertilizers are needed on most of the soils of Florida. 

 Except for the Everglades and associated areas, most of the 

 soils are coarse textured. Such soils account for about 28 

 million acres (11.3 million ha) or about 80% of the land area 

 of the state (3eaton et al . , 1971, p. 6). 



Research during the 1940 's and early 1950 ' s showed conclusively 

 that many crops growing on Florida soils would respond to S fertiliza- 

 tion. However, the conscious application of S as a fertilizer nutrient 

 has never received wide acceptance. Sulfate is applied in many fertil- 

 izer materials as an associate anion or as a by-product of the fertil- 

 izer manufacturing process. Ammonium sulfate, ordinary superphosphate, 

 sulfate of potash-magnesia, and gypsum may supply adequate quantities 

 of S to growing crops. Micronutrients applied in the soluble sulfate 

 form will also contribute to the S nutrition of plants. However, 

 intensively grown, high -producing crops are often fertilized with large 

 quantities of N as urea, anhydrous ammonia, or ammonium nitrate, P as 

 concentrated superphosphate, diammonium phosphate, or ammonium oolv- 

 phosphatas, and K as muriate of potash. If no S is included in the 

 fertilizer, this practice could lead to soil-S depletion and reduced 

 yields . 



Soils serve as a source and a sink for plant available S, but 

 attempts to measure plant-available and labile S have been only 



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