The Sources and Rates of Phosphate Fertilizers Influence Phosphorus Dynamics and Availability and the Productivity of Glycine max Grown in Cerrado Soil

In the Cerrado, phosphorus (P) availability is limited inter alia by the chemical characteristics of the soil. This study aimed to evaluate the effects of different sources and rates of phosphate fertilizers on P dynamics, soybean productivity, and plant nutrition in Glycine max cultivated in a Yellow Oxisol of the Maranhão Cerrado. Two experiments were conducted in a randomized complete block design during the 2021/2022 growing season. The first experiment followed a 5 × 3 factorial design, with five P sources (one control and four corrective sources) and three soil sampling depths. The second experiment used the corrective fertilization history of the areas from the first study as the first factor and three P2O5 rates applied at sowing as the second factor, with three replications. In the soil, Fe-bound P (P-Fe), Ca-bound P (P-Ca), Al-bound P (P-Al), and available P were evaluated; in the plant, grain yield, thousand-grain weight, total dry matter, and P concentration in leaves, grains, and the whole plant were determined. An interaction between P sources and soil depths was observed for P-Fe and P-Ca (0–0.10 > 0.10–0.20 > 0.20–0.40 m), indicating low vertical mobility of P in the soil profile. In addition, increasing P2O5 rates raised P contents in the soil and plant tissues across all treatments. For the Itafós source, soil P increased from 2.66 to 4.22 mg kg−1 at 0.0 and 120.0 kg ha−1 of P2O5, respectively, which resulted in a marked increase in soybean grain yield, rising from 1484.93 kg ha−1 at 0.0 kg ha−1 to 3418.60 kg ha−1 at 120.0 kg ha−1 of P2O5, highlighting the importance of adequate phosphate fertilization for agricultural systems in Cerrado soils. P-Al showed a positive correlation with soil available P, whereas P-Fe was correlated with the treatments TSP10, TSP0, and Itafós20.