Sugarcane Yield Response to Silicon Related to Extractable Soil Silicon on Florida Mineral Soils.

Silicon (Si) is a beneficial nutrient for sugarcane production to which there are well documented yield responses on Florida soils with low soluble Si. However, there are currently no University of Florida recommendations for Si application for sugarcane grown on mineral soils. With the goal of developing recommendations for Si application, the objective of this study was to evaluate sugarcane yield response to calcium silicate in relation to extractable soil silicon (0.5 M acetic acid) in mineral soils. Two small-plot trials were conducted to evaluate sugarcane response to calcium silicate containing 20% Si. Trial 1 was on Margate sand with six replications and calcium silicate rates of 0, 3.4, and 6.7 Mg ha^-1 with sugarcane cultivar CP 78-1628. Trial 2 was on Oldsmar sand with six replications and calcium silicate rates of 0, 2.2, 4.5, and 6.7 Mg ha^-1 and sugarcane cultivar CL 88-4730. There were significant responses in Mg sucrose ha^-1 to calcium silicate at each location with initial acetic acid-extractable Si (0-15 cm depth) of 21 g Si m^-3 in trial 1 and 46 g Si m^-3 in trial 2. Calcium silicate requirement for the soils at trials 1 and 2 were determined to be 6.7 and 4.5 Mg ha^-1, respectively. A linear plateau model for the combined dataset was determined relating relative sucrose yield for all crop years to soil-extractable Si in which a yield plateau was achieved at 117 g Si m^-3. These results will be used to develop recommendations for Si application for sugarcane grown on Florida mineral soils.