Abstract:In order to study the effects of different layered fertilization on nutrient transport, a soil column leaching experiment was conducted. Taking the mixed application (ploughing after fertilizer application) as control, and no fertilizer, common urea and controlled release urea were mixed with phosphorus and potassium fertilizer respectively. A layer (depth 5 cm), two layers (5, 10 cm), three layers (5, 10, 15 cm) were applied to study the total nutrient leaching and fertilizer nutrient leaching rate under different layered fertilization treatments. The results showed that the total amount of inorganic nitrogen leaching in the layered application of common fertilizer was significantly lower than the control, and the three-layer fertilization gave the lowest. The leaching of inorganic nitrogen was generally low in all layered fertilization treatments. The application of controlled release fertilizer did not reach a significant level compared with the control. All layered fertilization treatments had no significant effect on the total leaching of available phosphorus. Compared with the mixed application, and the total amount of available potassium leaching under controlled-release fertilizer layered fertilization was also the highest in the three-layer fertilization treatment. Different layered fertilizations showed a great difference in the leaching rate of fertilizer nutrient. The nitrogen leaching rate of common fertilizer application was 9.9%, and the leaching rates of common fertilizer under one layer, two layers and three layers application treatments were 6.31%. 4.91% and 2.7% respectivley, the leaching rates of layered fertilization treatments were significantly lower than that of mixed application. The leaching rate of controlled release fertilizer was 3.28%. The leaching rates of one layer, two layers and three layers applications of controlled release fertilizer were 1.48%, 2.00% and 2.63%, respectively, the leaching rate of layered fertilization treatments were lower than that of mixed application, but it did not reach a significant level. The loss rate of phosphate fertilizer treated by layered application of common fertilizer was between 0.03%~0.05%, and 0.07%~0.08% for the layered fertilization treatments, both of which did not reach the significant level. The leaching rate of mixed application of potassium fertilizer in the normal fertilizer layered fertilization treatment was 0.35%, and the leaching rates of one layer, two layers and three layers of fertilization treatments were 0.40%, 0.49% and 0.55%, respectively, among which, the leaching rate of three-layer treatment was significantly higher than the mixed application treatment. The leaching amount of controlled release fertilizer mixed with potassium treatment was 0.24%, and 0.20%, 0.27% and 0.37%, respectively for the one layer, two layers, three layers applicaiton treatments. The leaching rates of controlled release fertilizer under three layers application was significantly higher than that of mixed application. The pH of each treatment varied from 7.22 to 8.24. There was no significant difference in pH among treatments. The electrical conductivity decreased significantly with the leaching for all treatments. The electrical conductivity of the first leaching treatment was the same, i.e., 7 547.00~9 360.00 μS/cm for the common fertilizer, and 5 570.00~9 370.00 μS/cm for the controlled release fertilizer. The electrical conductivity decreased to 1 985.67~2 470.00 μS/cm and 1 804.67~2 576.67 μS/cm respectively at the fourth leaching time. In summary, the total leaching amount of inorganic nitrogen in the common urea layered fertilization was significantly lower than that of the mixed fertilizer, and the three-layer fertilization was the lowest. The inorganic nitrogen leaching amount of the controlled-release urea was lower than that of the mixed fertilizer, but the difference was not significant. The layered application had no significant effect on the total leaching amount of phosphorus; the total leaching amount of available potassium of the common fertilizer three-layer application was significantly higher than that of the mixed fertilizer treatment. With the increase of leaching times, the electrical conductivity of leachate decreased significantly for all treatments, but the pH increased with the different degrees.