黄土高原不同降水类型区旱作玉米田土壤干燥化效应与土壤水分承载力模拟研究

Simulation of yield and soil desiccation effects of continuous spring maize in different precipitation areas of the Loess Plateau

在模拟精度验证基础上,应用WinEPIC模型模拟研究了黄土高原不同降水类型区1960～2000年期间不同肥力水平下连作春玉米的产量变化和土壤水分效应。模拟结果表明:(1)洛川、延安、寿阳、榆林连作春玉米产量地区间差异显著,其年平均值分别为4.40、3.75、2.50、1.75t/hm2。施肥增产率和水分利用效率地区间差异均显著,均表现为洛川>延安>寿阳>榆林;同一地区水分利用效率随施肥量的增加而提高,不同地区施肥增产率最大值范围不同。(2)0～7m土层逐月土壤有效含水量地区间差异显著,洛川>延安>寿阳>榆林;同一地区内肥力水平越高,春玉米耗水量越大,逐月土壤有效含水量平均值越低。在春玉米生育期内0～7m土层年度土壤有效水分增减量地区间差异显著,洛川<延安<寿阳<榆林;不同肥力处理间的差异在模拟前期为显著,在模拟后期为不显著。(3)所有地区的春玉米在连作期间0～7m土层土壤湿度剖面分布,在经历了土壤湿度逐年降低、土壤干层逐年加厚的干燥化过程后,均出现了稳定的土壤干层。土壤干燥化速度地区间差异显著,洛川<延安<寿阳<榆林;不同肥力处理间随着施肥水平的提高土壤干燥化速度加快。(4)洛川、延安、寿阳、榆林连作春玉米的适宜产量水平分别为5.25～5.54、4.26～4.58、2.34～2.74、1.37～1.62t/hm2,相应的施肥水平分别为N240(N240kg/hm2,P120kg/hm2)～N300(N300kg/hm2,P150kg/hm2)、N180(N180kg/hm2,P90kg/hm2)～N240(N240kg/hm2,P120kg/hm2)、N120(N120kg/hm2,P60kg/hm2)～N180(N180kg/hm2,P90kg/hm2)、N60(N60kg/hm2,P30kg/hm2)～N120(N120kg/hm2,P60kg/hm2)。

Based on model validation,the Win EPIC model was used to simulate yield and soil desiccation effects of continuous spring maize under different fertilization treatments on different precipitation areas of the Loess Plateau during 1960-2000.The simulated results showed as following：（1）The difference of spring maize yield in Luochuan,Yan＇an,Shouyang,and Yulin was significant,and its average was 4.40 t/hm2,3.75 t/hm2,2.50 t/hm2 and 1.75 t/hm2,respectively.The difference of water used efficiency（WUE）and increased rate of yield by fertilizer（RYF）in Luochuan,Yan＇an,Shouyang and Yulin were both notable and reduced by the order.The WUE enhanced with the increase of fertilizer,and the maximum value of RYF was in different fertilizer range in difference areas.（2）Monthly available soil water in 0-7m soil profile was significantly different and the value of Luochuan,Yan＇an,Shouyang,and Yulin was reduced in sequence.In the same area,the higher fertilizer applied,the more water consumption,the less monthly available soil water remained.The difference of annual reduced soil water among different areas was significant,and increased with sequences of Luochuan,Yan＇an,Shouyang and Yulin.Difference of annual reduced available soil water in 0-7m soil profile among different fertilizer treatments was notable at the earlier simulation stage,but was not significant at the later stage.（3）A relative stable desiccated soil layers shaped in 0-7m soil profile after soil water depleted and desiccated soil layers thickened period.Soil desiccated rate in Luochuan,Yan＇an,Shouyang,and Yulin increased in the sequence.The higher fertilizer applied,the faster soil desiccate rate reached.（4）The suitable yield of continuous spring maize in Luochuan,Yan＇an,Shouyang,and Yulin was 5.25-5.54 t/hm2、4.26-4.58 t/hm2、2.34-2.74 t/hm2、1.37-1.62 t/hm2,respectively,and reasonable fertilizer amount in corresponding area was N240（N 240 kg/hm2,P 120 kg/hm2）-N300（N 300 kg/hm2,P 150kg/hm2）、N180（N 180 kg/hm2,P 90kg/hm2）-N240（N 240 kg/hm2,P 120 kg/hm2）、N120（N 120 kg/hm2,P 60kg/hm2）-N180（N 180 kg/hm2,P 90kg/hm2）、N60（N 60 kg/hm2,P 30kg/hm2）-N120（N 120 kg/hm2,P 60kg/hm2）,separately.