半干旱区草粮轮作田土壤水分恢复效应

Restoration of soil water in alfalfa-grain crop rotation fields on semi-arid region

采用野外实地观测和作物模型模拟相结合的方法,研究了不同轮作模式黄土高原半干旱区长期种植苜蓿地农田土壤水分恢复状况。结果表明:长期连作苜蓿地土壤干燥化进程与不同轮作模式下土壤湿度恢复的进程均表现为前期快后期慢;8～10m深层土壤湿度恢复困难,6～8年生苜蓿草地翻耕后适宜采用PPW轮作模式(马铃薯→马铃薯→春小麦)以恢复土壤水分,种植16～20a粮食作物后可以再次种植苜蓿。该研究结果可为黄土高原半干旱区苜蓿草地的土壤水分利用和恢复提供参考。

Restoration of soil water in alfalfa-grain crop rotation fields was observed and simulated in the semi-arid region of southern Ningxia by the combination of field investigation and crop model simulation. Results showed that：a high soil desiccation rate and soil water restoration rate appeared both in the earlier stage and a low rate appeared in the later stage in the process of formation of desiccation layer during alfalfa growth period and soil water restoration during alfalfa-grain crop rotation period. It was difficult to restore soil water in the 8-10 m layer soil. Considering the sustainable soil water use of alfalfa-grain crop system,PPW rotation system （with the sequence of potato,potato,spring-wheat） was the optimum pattern to restore soil water on desiccated alfalfa grasslands with 6-8 years old,and alfalfa can be planted again after PPW rotation for 16-20 years. Results of this study can provide references for the using and restoration of soil water in alfalfa land on the semi-arid area of the Loess Plateau.