112 

 organic matter and in the argillic horizons of the Ultisols because of 

 mineralogy. The Lakeland soil had the least S within its profile. 

 Other nutrient levels in these soils before treatment are presented 

 in Table 20. 

 8.2 YIELDS 

 8.2.1 Harvest 1 



The sorghum-sudangrass responded to S applications on the first 

 harvest in the Myakka soil although symptoms of S deficiency were not 

 observed (Table 21) . The Orangeburg and Norfolk soils provided ade- 

 quate S for the young plants during the 4 weeks of initial growth 

 (Tables 22 and 23) . Since no S was applied initially to the Lakeland 

 soil, no statement can be made concerning initial response to S on this 

 soil (Table 24). However, S concentration appeared to be adequate in 

 the plant tissue during the first 4 weeks of growth. Sulfur applied 

 after the first harvest significantly increased yields in the second 

 harvest. 



Part of the organic S in soils is considered to be unstable and is 

 abiologically converted to sulfate by air or oven drying. Biederbeck 

 (1978) reviewed the literature on this subject and found reports of 20 

 to 80% increases in extractable sulfate after air drying. Drying 

 causes an immediate release of S but has little effect on subsequent S 

 mineralization. Barrow (1961) warned of the effect this mineralized S 

 may have on the interpretation of pot experiments. Extractable sulfate 

 S was low in the soils of this stud\r even after air drying for several 

 weeks. After incubation at ambient temperature and subsequent drying, 

 treated soils were extracted to determine any changes in the relative 

 amounts of sulfate removed by the extractant. Extractable S was 



