Seasonal Changes in Nutrient Availability for Sulfur-Amended Everglades Soils Under Sugarcane.

The Everglades Agricultural Area (EAA) in south Florida was drained in the early 1900s for agricultural production. Long-term tillage resulted in incorporation of CaCO₃ into the soil profile from underlying bedrock, increasing the pH to approximately 7.0-7.5.  In some cases, elemental S is used to reduce soil pH for the purpose of increasing nutrient availability.  The objective of this study was to evaluate effects of elemental S addition on soil pH and availability of macro- and micronutrients during the sugarcane growing season.  Sulfur application did not significantly reduce soil pH when applied at 0 to 448 kg S ha^-1 due to the high soil buffering capacity.  Water extractable P and K for soils receiving the highest S rate were 188% and 71% higher than for unamended soils only at 2 months after application, indicating a short-term enhancement of macronutrient availability.  Soil amended with 448 kg S ha^-1 contained 134% more acetic acid-extractable Zn than unamended soil, although stimulatory effects did not extend beyond 2 months.  Sugar yield was not affected by S addition, averaging 17 Mg sugar ha^-1.  The failure of S to enhance nutrient availability throughout the growing season indicates the limited benefit of applying elemental S to reduce pH and increase nutrient availability to sugarcane.