Effects of fertilization level on soil water in winter wheat field

Based on model validation, the WinEPIC model was used to simulate soil desiccation of continuous winter wheat under different fertilization treatments in Changwu dry highland. The simulated results show that simulated monthly available soil water content of all 4 fertilization treatments decline with annual and seasonal precipitation changes, average annual decreasing rates are 8.6, 8.6, 11.1 and 13.7 mm separately, and differences of soil water content among low fertilization and medium and high fertilization treatments are very significant, but no significant difference between no fertilization and low fertilization treatments. Soil moisture decreased and desiccated soil layers thickened gradually at beginning of simulation, and stable desiccated soil layers occurred after 5-8 years of continuous cropping simulation. Distribution depth of desiccated soil layers are 2-3 m of no fertilization and low fertilization treatments, and 2-4 m and 2-5 m of medium and high fertilization treatments respectively. The desiccated soil layers thicken with the increasing fertilization and crop yields. Annual water consumption amounts of 4 fertilization treatments are similar and decrease gradually with fluctuation, but soil water overuse of medium and high fertilization treatments are 91 mm and 203 mm separately than no fertilization treatment during the first to the fourth year period. Soil water carrying capacity of dry highland wheat field is 1.422-2.405 t/hm², and its fertilization amounts are N 45-90 kg/hm² and P 15-30 kg/hm².