不同地区土地沙漠化过程中土壤退化演变规律

Land Degradation Processes during Desertification Processes in Three Typical Regions

对不同地区沙漠化土地演变过程与土壤理化性质的相互关系和分异规律进行了研究。结果表明：（1）各地区的沙漠化土地土壤养分含量具有K多．P少，N贫乏的特征；（2）在沙漠化过程中，土壤退化的分异规律与地区分带性有关。其中土壤有机质、速效P、速效K的受损程度为西部区〉中部区〉东部区，全N为中部区（91．49％）〉东部区（67、30％）〉西部区（61．45％），全盐为中部区（52．94％）〉西部区（43．00％）〉东部区（20．00％）；（3）速效K和速效P及全盐的分布格局具有明显的地带性特征，其中速效K为西部区（228．8～81．4mg／kg）〉东部区（62．5～32．5mg／kg）〉中部区（40．1～19．2mg／kg），速效P为东部区（7．84～3．45mg／kg）〉中部区（4．84～2．19mg／kg）〉西部区（2．73～0．72mg／kg），全盐为西部区（7．75～1．18g／kg）〉中部区（0．57～0．08g／kg）〉东部区（0．10～0．04g／kg）。土壤盐分与沙漠化关系不明显．而与水环境和人为经营活动有关；（4）从总体上看，土壤机械组成受沙漠化影响的程度为东部区〉中部区〉西部区；其中西部砂粒受损率低于东部、中部．但粉砂高于东部、中部，而粘粒却低于东部、高于中部；（5）中部和东部区砂粒递增高峰期和粉砂与粘粒的递减高峰期（轻度后）均早于西部区（中度后）。在时间序列上中部和东部区受抄漠化危害较西部区早，因此在中部和东部区应重视沙漠化土地的早期防治。

This paper is aimed at correlation between desertiflcatlon processes and soil physio-chemical properties. The results show that： （1） soil nutrient is characterized by richer K, less P and poorer-N in desertified land; （2） during sandy desertification processes, the regulation of soil degradation is close related to zonality, the decreasing trend of soil organic matter （SOM）, available P and available K is western region 〉 middle region eastern region, the decreasing trend of total N is middle region 〉 eastern region 〉 western region, and that total salt content is middle region 〉 western region 〉 eastern region; （3） regionalized differences of available K, available P and total salt content are obvious, among which available K shows western region（228.8～81.4mg/ kg）〉 eastern region（62.5～32.5 mg/kg）〉 middle region （40. 1～ 19.2 mg/kg）,available P shows eastern region （7.84～3.45 mg/kg）〉 middle region （4.84～2.19 mg/kg）〉 western region（2.73～0.72 mg/kg）,total salt content shows western region （7.75 ～ 1.18 g/kg）〉 middle region （0.57 ～ 0.08 g/kg）〉 eastern region （0. 10～0. 04 g/kg）, soil salt content has not significant correlation to sandy desertification, but close relation to water environment and human activities; （4） soil texture affected by sandy desertification shows eastern region middle region 〉 western region, in the western region, the decreasing rate of sand content is less than that in eastern and middle regions, that of silt content is more than two other regions, and that of clay content is less than eastern region but more than middle region; （5）the peak period of sand content increasing and silt and clay content decreasing in middle and eastern regions is earlier than that in western region, showing these two regions are affected earlier than western region, hence, sandy desertification in these two regions should be control as early as possible.