沙漠-绿洲交错带小麦地土壤养分变化特征对耕种时间的响应

利用相关分析及土壤退化指数，对比研究了古尔班通古特沙漠与奇台县绿洲交错带荒地、盐碱地、小麦地土壤的养分含量、指数的特征、变化规律和退化程度。结果表明:（1）土壤有机质与表层全氮呈相关性较高的正相关，与碱解氮相关性差。（2）土壤表层速效养分含量下降快于下层。（3）随耕种时间的延长，小麦地土壤养分的全氮、全磷、全钾含量变化较小，而速效成分均大幅度的下降。其中，速效钾下降速度最快，达-38.18 mg/（kg·a），碱解氮其次，为-14.875 mg/（kg·a）；速效磷仅为-4.486 mg/（kg·a）。（4）未耕地的土壤养分退化指数（SNDI）为-11.30%，明显低于耕种的小麦地。（5）小麦地的年均土壤养分退化指数在最初的3年里为4.317%，随后的2年（5年）是6.485%，而后5年（10年仅为0.788%，即早期退化速度快，随着耕作年限的增加（> 5年），土壤退化速度迅速减缓。

Responses of Soil Nutrients Variation Characteristics to the Cultivation Years in Wheatland of Desert-Oasis Ecotone

In this paper, a comparative study was conducted to investigate soil nutrient content, index characteristics, evolvement rules and degradation degree of wastelands, alkali soils, wheat lands in the Gurbantunggut Desert-Qitai Oasis ecotone by using correlation analysis and soil degradation index(SNDI). The results showed that the positive correlation between soil organic matter of the surface layer and total nitrogen was higher, and soil organic matter of the surface layer had the poor relation to available nitrogen; available nutrients of the surface layer declined faster than those in the deeper layers; with the extension of cultivation years in wheat lands, the total nitrogen, total phosphorus, total potassium content changed little, and the available nutrients presented the great decrease, and available kalium -38.18 mg/(kg·a)], available nitrogen-14.875 mg/(kg·a)], available phosphorus -4.486 mg/(kg·a)] were ranked the first, the second, and the third, respectively; SNDI of the untilled lands was -11.30%, and it was significantly lower than that that in wheat lands; SNDI in untilled lands was 4.317% in the first three years, and it was 6.485% in the following two years(5 a), and it finally was 0.788% in the following five years(10 a), which meant the soil degradation rate was faster in the early years, with the extension of cultivation years, SNDI reduced slowly.