Silicon application timing on phosphorus availability and fractionation in tropical soil and its effects on maize growth

Background and Aims Phosphorus (P) is a limiting nutrient for agricultural production in tropical soils due to its adsorption onto Fe and Al oxides. Silicon (Si) also exhibits affinity for these compounds and can displace P into the soil solution. Studies evaluating application timing to increase P availability remain scarce. This study evaluated the effect of Si and P application timing on soil P availability and maize growth. Methods The experiment was conducted in a greenhouse using a randomized block design with four replicates. Six treatments were evaluated: Control (without P and Si); P applied at sowing (100 mg kg⁻ 1 ); Si applied at sowing (480 mg kg⁻ 1 ); P applied 30 days before sowing + Si at sowing; Si applied 30 days before sowing + P at sowing; and P + Si applied together at sowing. At 60 days of maize cultivation; physiological parameters, biomass, P and Si concentration and uptake, and soil P fractionation were evaluated. Results The results demonstrated that Si applied 30 days before sowing + P at sowing, or P + Si applied together at sowing, increased available P in soil. The P + Si combination, regardless of the application timing, did not increase P concentration and uptake in maize plants. Conclusion The application of Si before P, or the joint application of P and Si, can be an alternative to increase available P levels in tropical soil, however, no influence of the timing of P and Si application was observed on maize growth.