60 

 soils studied and produced increased yields of grasses and legumes an 

 average of 1100 kg/ha when S was added. A Red Bay fine sandy loam 

 (Rhodic Paleudult) from west Florida did not produce a S response bv 

 the crops studied, but the addition of S did cause higher S concentra- 

 tions in the plant tissue. The addition of S to all soils at the rate 

 of 34 kg/ha increased the S concentration of the plants by 0.10 of a 

 percent. Critical levels of S were established for several crops. 

 These are listed in Table 6. 



Neller's paper on the increase in extractable sulfate with an 

 increase in the clay content in the profile of a number of Florida 

 soils (Neller, 1959), led to the realization that some deep-rooted 

 crops may not respond to S on low-S soils because adequate S is avail- 

 able from deeper soil horizons. Researchers working with Ultisols in 

 other areas of the southeastern United States have made similar con- 

 clusions (Ensminger, 1958; Jordan, 1964; Anderson and Futral, 1966; 

 Murdock and Lund, 1979). 



Recently, Mitchell and Gallaher (1930) observed S-deficient, 

 seedling, field corn on an Arredondo fine sand in north Florida. They 

 were unable to increase yields by foliar and soil 5 applications 

 although S concentrations were increased in the plant tissues by the S 

 treatments. All plants had grown out of the S-deficient conditions by 

 55 days; they assumed that plant roots were able to reach adsorbed S 

 associated with the argillic horizon at 60 to 80 cm. Soil in the Bt 

 horizon contained 5 to 8 times more S than soil in the to 60-cm 

 depth. 



Most of the research with S on Florida soils was done during the 

 1940 's and 1950's. Since that time there have been few positive 



