Silicate Fertilization in Sugarcane: Silicon Availability, Uptake, and Recovery Index Over Two Consecutive Cycles

Multiple harvests of sugarcane with high silicon (Si) uptake decrease Si soil levels, and Si fertilization may be necessary. The association of Si levels in soil, uptake, and recovery from silicate could enhance the understanding of the efficiency of Si fertilization. The objectives were to evaluate the effects of silicate rates applied in furrows at planting on soluble Si contents at two depths, Si uptake, the correlation between Si in the soil and Si in the leaves, and the recovery index (RI) of Si from silicate during two consecutive cycles of sugarcane cultivars. The experiment was conducted in randomized blocks with four Si rates (0, 55, 110, and 165 kg ha(-1) Si) as silicate and two sugarcane cultivars (IAC87-3396 and SP89-1115) in two consecutive cycles. Silicate fertilization increased the Si extracted by 0.5 mol L-1 acetic acid and 0.01 mol L-1 CaCl2 at 0-25 cm after 6, 17, and 29 months, while this only occurred with acetic acid at 25-50 cm and CaCl2 after first ratoon. Both Si extractants showed a satisfactory correlation (R = 0.40-0.52) with Si concentration in the top visible dewlap leaves, enabling the evaluation of the Si availability in soil samples from 0 to 25 cm and 25 to 50 cm after 6 months. There was 40% Si recovery from silicate over the two consecutive cycles. Si application in furrows at planting is a potential tool to increase Si availability in soil at 0-25 cm, Si uptake by stalks, and Si recovery from silicate after two consecutive cycles.

Automated summary

Applying different rates of silicate in furrows at planting can increase the availability of Si in soil, enhance Si uptake by sugarcane stalks, and promote the recovery of silicate.