为揭示川西北若尔盖草原在草地沙化过程中土壤颗粒组成和矿质养分的变化特征,文中通过野外调查和室内分析化验,研究了川西北沙化过程中草地的土壤颗粒组成及磷、钾的变化特征。结果表明:草地沙化过程中0-100cm土层土壤结构受到了严重破坏,呈现出明显的粗化特征,土壤砂粒含量显著增加,粉粒、粘粒、土壤速效磷和速效钾含量显著减少。其中,0-20cm土层变化最为明显,极重度沙化草地土壤完全沙化,沙粒含量高达95.83%,相对未沙化草地增加了28.15%,速效磷、速效钾含量非常缺乏,分别仅为3.64mg·kg-1、24.66mg·kg-1,相对于未沙化草地分别降低了52.79%和74.29%。说明在沙化草地治理过程中,需及时补充适量的磷钾矿质养分。不同草地退化阶段研究表明,未沙化草地至中度沙化草地演变过程中,沙粒含量显著升高,粉粒、粘粒、速效磷、速效钾均有极显著降低,说明沙化草地的治理应将轻中度沙化阶段作为关键时期。 In order to reveal the changes of soil particle composition and mineral nutrients in the process of grassland desertification in the Ruoergai steppe of northwestern Sichuan, the changes of soil particle composition and phosphorus and potassium in the grassland during the desertification in northwestern Sichuan were studied through field investigation and laboratory analysis. The results showed that the soil structure of 0-100cm soil layer was severely damaged during the process of grassland desertification, showing obvious coarsening characteristics. The contents of soil sand increased significantly, and the contents of silt, clay, soil available phosphorus and available potassium decreased significantly. Among them, the most obvious change was in 0-20cm soil layer. The soil of extremely severe desertified grassland was completely sandy, the content of sand was as high as 95.83%, the relative un-desertified grass increased 28.15%, the content of available phosphorus and available potassium were very scarce, which were only 3.64mg · kg-1 and 24.66 mg · kg-1, respectively, decreased by 52.79% and 74.29% compared with that of the non-desertified grassland. This shows that in the process of desertification grassland management, the appropriate amount of phosphorus and potassium mineral nutrients needs to be replenished in time. The study of different grassland degradation stages showed that the content of sand grains increased significantly in the process of the evolution from un-desertified grassland to medium desertified grassland, and the grain, clay, available phosphorus and available potassium all decreased significantly, indicating that the treatment of desertified grassland should be Light and moderate desertification stage as a crucial period.