Silicate fertilization of sugarcane cultivated in tropical soils

Although the benefits of silicon (Si) fertilization for sugarcane yields have already been demonstrated, few studies have examined the effects of silicate fertilization applied at less than 200 kg ha−1 Si in the furrow at planting on the soluble Si concentration in the soils, plant uptake in sugarcane (a Si-accumulating crop) and damage caused by the stalk borer (Diatraea saccharalis) under field conditions. The objective of this study was to evaluate the effects of a Ca–Mg silicate that was applied in the furrow at planting on the available Si in the soil, sugarcane yields and stalk borer damage of two sugarcane cultivars under field conditions. Two experiments were conducted on two soil types with a low silicon content (a Typic Quartzipsamment-Q and a Rhodic Hapludox-RH) using a completely randomized factorial scheme design with four replicates, four Si application rates (0, 55, 110 and 165 kg ha−1 Si) and two cultivars (IAC 86-3396 and SP 89 1115). Ca–Mg silicate was applied during furrow planting such that all plots received the same quantity of Ca and Mg. On both of the soil types, silicate fertilization increased the Si concentrations in the soil and the leaves of the plants at 8 months for both the plant cane and the first ratoon, thereby showing residual effects. Additionally, the potential for silicon fertilization applied in the furrow at planting to reduce stalk borer (D. saccharalis) damage was confirmed for stalk Si concentrations that were greater than 3 g kg−1 Si as shown in the RH soil experiment. Therefore, the practice of silicate placement at low rates (<200 kg ha−1 Si) in the furrow at planting should be considered an alternative method of nutritional management for sugarcane in sandy and loam sandy soils with additional benefits of increased soluble Si in the soil, Si uptake and sugarcane yield and may help reduce the stalk borer damage of D. saccharalis.