Phosphorus Contents in the Profile of an Oxisol With Continuous Application of Liquid Swine Manure

This study aimed to evaluate the dynamics of phosphorus in the soil by the determination of phosphorus contents in an Oxisol cultivated with soybean during the 2016/2017 crop season, after 17 years of successive applications of liquid swine manure (LSM). The experiment was conducted in the experimental area of the University of Rio Verde. The treatments were: T1-control; T2-25 m3 ha-1 of LSM; T3-50 m3 ha-1 of LSM; T4-75 m3 ha-1 of LSM; T5-100 m3 ha-1 of LSM and T6-fertilization with mineral fertilizer. The subplots refer to soil depths: 0-10; 10-20 and 20-40 cm. The LSM was applied to the soil surface by spraying, before soybean sowing and the mineral fertilizer was applied to the furrow at the time of planting. After soybean harvesting, soil samples were collected at the studied depths for the determination of the contents of P in the soil. The contents of P in percolated water are within the concentration range considered adequate for human consumption. As for the contents of P in the soil, LSM applications on the soil surface increased the available soil P up to the depth of 20 cm. The highest dose of LSM applied to the soil promoted an increment of P contents that are within the safety range of the critical environmental limit of phosphorus (LCA-P), corresponding to 37% of this limit.