黄土高原沟壑区不同种植系统土壤水分消耗和恢复

黄土高原的土壤干燥化是影响粮食生产可持续发展的关键因素之一，研究土壤干层形成和恢复对该地区粮食生产的可持续发展具有重要意义。该文通过对长期定位观测数据的分析，探讨了不同种植体系和降水年型对土壤水分消耗和恢复的影响。结果表明：与裸地相比，玉米地土壤水分减少最多的月份大多出现在8月或9月，小麦地主要出现在5、6、7月3个月，苜蓿地主要出现在6月或8月；1985－1990年的6 a间，玉米、小麦和苜蓿地生育期内0～2 m土层土壤水分相对裸地平均分别减少了32.52、60.27和86.47 mm。旱作玉米地的土壤水分在平水年型可以得到完全恢复；旱作小麦地在丰水年型或者遇到强降雨的月份土壤水分在0～3 m范围内可以得到恢复，但较难恢复到试验初期的土壤水分。旱作苜蓿地0～3 m范围的土层在降雨较多的年份能够得到一定程度的恢复，6～10 m的土壤水分很难恢复。

Depletion and restoration of soil water in different cultivating systems in Gully Region of Loess Plateau

Soil desiccation is one of the key factors to influence the sustainable development of crop production on the Loess Plateau of China. So it has a great significance for the sustainable development of crop production to research the form and recovery of the dry layer of soil. In this article, depletion and restoration of soil water in different cultivating systems were analyzed based on the long-term experiment data at Changwu Agriculture Experimental Station. The results showed that comparing with bare land, the time in which maximal reduction of soil water occurred was August or September in maize land; May, June or July in wheat land; June or August in alfalfa land. In the growth period, from 1985 to 1990, the average soil water in 0-2 m soil layer of maize land, wheat land and alfalfa land decreased by 32.52, 60.27 and 86.47 mm compared with that of bare land. The restoration of soil water in different cultivating systems was different. Soil water of entire dry layer in maize land was thoroughly restored in high precipitation years. Soil water of part dry layer (0-3 m) was restored in wheat land in high precipitation years or in heavy rainfall months, but it was relatively hard to restore to its original level. Soil water in alfalfa land restored to a certain extent in the 0-3 m soil layer in rainy years but hard to restore in the 6-10 m soil layer.