施肥水平对冬小麦田土壤水分影响的模拟

在模拟精度验证基础上,应用WinEPIC模型模拟研究了黄土高原长武早塬地1957～2001年期间不同肥力水平下连作冬小麦田的土壤干燥化效应.结果表明:4种肥力处理下连作冬小麦逐月土壤有效含水量均呈现波动性降低趋势,平均每年分别减少8.6、8.6、11.1和13.7 mm,无肥和低肥与中肥和高肥处理间土壤有效含水量差异十分显著,但无肥和低肥处理间无明显差异;在模拟初期出现了土壤湿度逐年降低、土壤干层逐年加厚的干燥化过程,在连作第5～8年以后均出现了稳定的土壤干层,无肥和低肥处理土壤干层均分布于2～3 m土层,中肥和高肥肥处理分别分布于2～4 m和2～5 m土层,随肥力和作物产量水平的提高,土壤干层厚度增厚;4种肥力处理麦田生产年度耗水量接近且呈现波动性缓慢降低趋势,但前1～4年中肥和高肥处理麦田共计较无肥处理麦田多耗水91和203 mm,长武旱塬地麦田土壤水分承载力为1.422～2.405 t/hm2,相应的肥力水平为N45～90 kg/hm2和P 15～30 kg/hm2.

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.