长武旱塬草粮轮作田土壤水分可持续利用模式模拟

采用实地观测和计算机模拟相结合的方法，以长期定位试验数据为基础，通过对不同草粮轮作模式的模拟研究，分析了长武旱塬草粮轮作田的土壤水分恢复效应，以期探索出适合该地区的土壤水分可持续利用的草粮轮作模式。验证结果表明：草粮轮作田0～2 m土层土壤贮水量模拟值和观测值间的相关系数为0.97；0～5 m土层土壤湿度的模拟值和观测值间相关系数在苜蓿草地、冬小麦田和马铃薯田分别为0.94、0.93和0.87，均达到了极显著水平。模拟结果表明：苜蓿翻耕后，种植马铃薯和糜子均有利于土壤水分的恢复。在土壤干燥化程度较严重时，种植冬小麦或者春玉米能够在一定程度上缓解土壤干燥化；在无干燥化或者干燥化程度较轻时，种植冬小麦和春玉米会导致土壤含水率的下降。在长武旱塬，“马铃薯-糜子-春玉米-马铃薯-糜子-冬小麦”的粮食轮作模式有利于苜蓿地土壤水分恢复，持续种植9～12 a后可以再次种植苜蓿。

Simulation of sustainable use of soil water in dry land for alfalfa-grain rotation system at Changwu arid-plateau of China

In order to find out a grain-crop system for sustainable usage of soil water, effects of different alfalfa-grain rotation systems on soil water restoration were simulated and investigated, based on long-term experiment at Changwu arid-plateau, by combining on-spot investigation and computer simulation methods. Validation results showed that correlation coefficient between simulated and observed values of soil water storage in 0-2m soil for alfalfa-grain rotation system (4-years-old-alfalfa, potato, winter-wheat, winter-wheat and winter-wheat) was 0.97(a<0.01). The correlation coefficient between simulated and observed value of soil moisture in 0-5m soil for alfalfa land, winter-wheat field and potato field was 0.94(a<0.01), 0.93(a<0.01) and 0.87(a<0.01) respectively. Simulation results showed that the cultivation of potato and broomcorn millet was benefit to recover soil desiccation. When spring maize or winter wheat cultivated, soil water varied with soil desiccation grade. When soil desiccation grade was serious, soil water restored slowly; when soil desiccation was slight, soil water reduced. Grain crop rotation system with annual sequence of potato, broomcorn millet, spring maize, potato, broomcorn millet and winter wheat was benefit to restore soil water after alfalfa plantation. At Changwu arid-plateau, alfalfa could be replanted after its cultivation years reached to 9-12 years.