36 

 occurred at Jay (pH 3.76) and at Gainesville (pH 3.93) in northern 

 Florida. Sites north of Lake Okeechobee have annual (volume-weighted) 

 pH values in the range of 4.6 to 4.8 while those south of the lake 

 have pH values approaching geochemical neutrality (pH 5.6) . 



These data for Florida are similar to those reported by Jones 

 (1976) and Jones et al. (1979) for South Carolina. For the period 1973 

 to 1975, the mean annual amount of S deposited in South Carolina soil 

 through precipitation was 11.3 kg/ha. This compared to 6.3 kg/ha for 

 1953 to 1955. In addition, Jones et al. (1979) used a factor reported 

 by Alway et al. (1937) to estimate gaseous S adsorbed by the soil from 

 S adsorbed by PbO candles at 15 locations. This value increased from 

 2.8 kg/ha in 1973 to 13 kg/ha in 1977. Total S added annually to South 

 Carolina soils from atmospheric sources ranged from 11.2 kg/ha in 1973 

 to 20.3 kg/ha in 1976. . 

 1.3 FERTILIZER SOURCES 



The sources of plant-available S that have been previously dis- 

 cussed are largely beyond the control of the crop producer. The amount 

 of fertilizer S applied to a crop or soil is completely dependent upon 

 management and may be the most significant source of S for modern crops 

 growing on sandy, low-S soils. 



Sulfur has traditionally been applied in fertilizers containing 

 ordinary superphosphate (12% S), ammonium sulfate (24% S) , gypsum 

 (18% S) , and other S-containing materials. When sufficient amounts of 

 the macronutrients were applied, available S was abundant. With the 

 introduction of high-analysis N and P materials, the S content of 

 fertilizer materials and mixes has decraased. Beaten et al. 

 reported that "... while the consumption of N, P ? 0., and K 



