Extractable soil silicon in relation to sugarcane yield on mineral soil

Florida sugarcane production is mostly on organic soils, but the cultivation area on mineral soils is also expanding. Silicon (Si) is beneficial for sugarcane growth and development on weathered soil. However, the low solubility and availability of soluble Si is an issue in Florida's mineral soils. This study aimed to assess soil Si extraction methods based on sugarcane yield response to calcium silicate application. It also examined the relationship between sugarcane yield with extracted plant-available soil Si, alongside plant Si concentrations. The experiment followed a randomized complete block design involving 2 fields, with 24 plots each, and 6 replications. Four rates of calcium silicate (0 control, 2.24, 4.48, and 6.67 Mg ha(-1)) were applied before planting sugarcane. Soil samples were collected prior to planting and after each harvest. Soil Si was extracted using 0.5 M acetic acid, 0.7 N NH4OAc, Mehlich 3, and 0.01 M CaCl2 extractants. Leaf samples were collected over a three-year sugarcane life cycle (from 2019 to 2022) to evaluate the relationship between soil Si and leaf Si concentrations. The relationships between parameters were analyzed using linear and nonlinear regression models. Results indicated that higher Si application rates increased Si concentrations in sugarcane leaves in both fields. However, only one field showed a yield response to Si, likely due to high pre-plant soil Si in the other field. The best extractant should correlate strongly with either yield or leaf Si content, but no single extractant showed a strong correlation with either, making it infeasible to identify the best extractant.