黄土高原半干旱偏旱区草粮轮作田土壤水分恢复效应模拟

Simulation on the restoration effect of soil moisture in alfalfa (Medicago sativa)-grain rotation system in semi-arid and drought-prone regions of Loess Plateau

采用实地调查和EPIC模型相结合的方法,模拟研究了黄土高原半干旱偏旱区不同草粮轮作模式的土壤水分恢复效应.结果表明:多年生苜蓿地和苜蓿翻耕后种植粮食作物农田0～10m土层土壤湿度调查值与模拟值间的相关系数均超过0.9(P<0.01),相对均方根误差在0.05～0.16,相对误差均低于10%;模拟与实测的土壤湿度剖面分布变化趋势一致.在黄土高原半干旱偏旱区,苜蓿地深层土壤干层恢复难度较大,在种植苜蓿期间应避免8～10m土层土壤湿度降到5.7%以下.苜蓿地适宜种植年限为4～6a,最长不应超过8a.苜蓿翻耕后适宜采用马铃薯→马铃薯→春小麦轮作模式进行土壤水分恢复,32～33a后可以再次种植苜蓿.

With the combination of field survey and EPIC modeling,this paper simulated the restoration effect of soil moisture in different alfalfa （Medicago sativa）-grain rotation systems in semi-arid and drought-prone regions of Loess Plateau. In perennial alfalfa field and in grain crop field after alfalfa,the correlation coefficients between the simulated and observed values of soil moisture content in 0-10 m layer were larger than 0.9 （P0.01）,and their relative root mean square errors were between 0.05 and 0.16,with the relative errors less than 10%. The dynamic changes of the simulated soil moisture contents in different soil layers were consistent with those of the observed values. In the study regions,it was difficult for the restoration of soil moisture in the deep soil layers of alfalfa field. During the cultivation of alfalfa,the soil moisture content in the layers at 8-10 m depth should not be less than 5.7%. Considering the sustainable development of agricultural production,the appropriate cultivation duration of alfalfa should be 4-6 years and no more than 8 years. For the restoration of soil moisture after alfalfa cultivation in the study regions,the rotation system potato （Solanum tuberosum） → potato → spring wheat （Triticum aestivum） could be adopted,and alfalfa could be cultivated again after 32-33 years.