Application and Residual Effect of Phosphorus and Silicon in Tropical Soils: Influence on Nutrient Accumulation in Rainfed Rice

Abstract Rice is essential for global food security. However, the effects of phosphorus (P) and silicon (Si) interaction on macronutrient accumulation in rice grown in tropical soils remain poorly understood, particularly regarding the persistence of these effects in subsequent crops. This study aimed to investigate the combined influence of Si and P levels on the accumulation of macronutrients (N, P, K, Ca, Mg, and S) and Si in the shoots of rice plants grown in two consecutive cycles in tropical soils with contrasting textures. Experiments were conducted in a randomized block design using a 4 × 4 × 2 factorial scheme with four P levels (0, 50, 100, and 200 mg kg⁻¹), four Si levels (0, 240, 480, and 960 mg kg⁻¹), and two soil types (clayey and sandy), with four replications. In experiment I, Si and P levels were applied, whereas experiment II evaluated only their residual effects. In both experiments, the accumulation of N, P, K, Ca, Mg, and S in rice shoots was determined. The combined application of Si and P significantly affected macronutrient accumulation, and responses varied with soil texture. In general, the Si–P interaction increased P and other nutrient accumulation, with stronger responses in the first cycle, although residual effects were also observed in the subsequent cycle. The interaction between Si and P can improve nutrient use in rice plants, and its effectiveness depends on soil texture.