126 



Sulfur had no effect on yields in 1978 (Table 26). The 400 kg/ha 

 N rate increased yields by 42% over the 200 kg/ha rate after the first 

 harvest (Fig. 13). Even though applied S did not increase yields, S 

 concentrations in the harvested forage and total S uptake increased 

 with increased S rates. Where S was omitted, an average of 14.2 and 

 17.6 kg/ha/yr of S was removed at low and high N rates, respectively. 

 At the highest rate of S, these values were 23.4 and 30.6 kg/ha/yr at 

 the two N rates (Table 27). 



Trends toward increased yields with S fertilization were evident 

 during the second year of the experiment (Table 28) . Sulfur had no 

 effect on dry matter yields at the lower rate of N at any harvest. At 

 the high N rate, the 10-kg/ha S rate increased yields at all harvests. 

 Additional N increased yields by 20" without S and almost 40% with 

 applied S (Fig. 13). Additional S beyond the 10 kg/ha rate did not 

 significantly increase yields. No noticeable symptoms of S deficiency 

 were observed in the field. 



Applying S in split applications throughout the season had no 

 apparent benefit. Even the fourth harvest in late September, 6 months 

 after gypsum application, showed significant increases in S concentra- 

 tion in the tissues with increasing S rates. Rhue and Kamprath (1973) 

 showed that 56 kg/ha of S as gypsum was completely leached from the 

 surface 45 cm of a Wagram loamy sand during 180 days. This experiment 

 was conducted during the winter months in North Carolina. One would 

 expect an even higher rate of leaching during a Florida growing season 

 where heavy summer rainfall occurs. There were no detectable differ- 

 ences in extr3ctable sulfate S in samples from the plots taken in the 

 fall of 1978 and again in the fall of 1979 (Table 29). Bahiagrass 



