106 



These argillic horizons are obviously an important source of plant- 

 available sulfate. If extractable and total S are a reasonable measure- 

 ment of the available and reserve S levels in a soil, then young seed- 

 lings would find little difference in the native fertility levels of 

 the upper 50 to 60 cm of Florida Ultisols and Spodosols. Plants grow- 

 ing on Ultisols, on the other hand, have a tremendous supply of availa- 

 ble sulfate in argillic horizons if the roots are able to penetrate 

 and absorb this sulfate. If the two Red Bay soils are excluded from 

 calculations, there were means of 8 and 25 kg/ha of available S in the 

 A2 and A2 horizons, respectively. In the upper 200 cm, over 460 kg/ha 

 of sulfate S was available. This value was estimated from the ten 

 soils studied. Values ranged from a low of 34 kg/ha in an Albany soil 

 from Washington County to a high of 1,350 kg/ha in a Dothan soil from 

 Santa Rosa County. 

 7.4 C:N:S RELATIONSHIPS 



The mean C:S and N:S ratios for the three soil orders are present- 

 ed in Table 18. The values are probably meaningless for the B horizons 

 of the Ultisols and the C horizons of the Entisols because there were 

 no significant correlations between soil S and organic C in these hori- 

 zons. The correlations of total S with organic C and total N in the 

 surface horizons of the Florida soils studied are as high or higher 

 than Nelson (1964) obtained for 12 Mississippi soils and Tabatabai and 

 Nelson (1972b) found in soils from Iowa. Biederbeck pointed out in 

 a recent review of organic S in soils that "... since the bulk 

 of the S in non-calcareous soil is in organic forms, total S usually 

 decreases sharply with soil depth" (Biederbeck, 1973, p. 279). This 

 statement is apparently not true for many Florida soils. Sulfate S 



