沙漠化逆转对表土颗粒组分中有机碳和养分分配的影响——以宁夏盐池县为例

The Influence of Desertification Reversal on Organic Carbon and Nutrients Distributions in Surface Soil Particle: A Case Study in Yanchi County, Ningxia Hui Autonomous Region

从时空转换的角度出发,采用物理分离的方法,获得宁夏盐池县多年围封区沙漠化逆转过程中不同土壤粒径的组分,并进行了各组分中有机碳和养分含量的测定。结果表明:随沙漠化程度的减小,中粗砂、极细砂和粘粉粒组分中土壤有机碳(SOC)和氮、磷、钾(N、P、K)含量与全土组分中各养分含量的变化一致,均呈增加趋势;其中,与中粗砂和极细砂结合的非保护性颗粒养分对沙漠化逆转的响应和敏感程度较大。沙漠化逆转过程中,颗粒组分SOC和N、P、K养分的含量和富集系数,均为粘粉粒>极细砂>中粗砂,表层土壤中粘粉粒含量的增加对维持SOC和N、P、K养分的固存起着主要作用;沙漠化逆转过程中随着粘粉粒的不断沉积,与粘粉粒结合的相对稳定的SOC和N、P、K养分的相对数量不断增多,与中粗砂和极细砂结合的非保护性颗粒SOC和N、P、K养分的相对数量逐渐减小,SOC和N、P、K养分的稳定性上升。

From the perspective of time-to-space conversion, the reversal of desertification in enclosed area for many years of Yanchi County was taken as a research object. By adopting the physical separation technique, different soil particle size components were obtained. Subsequently, we measured the contents of organic carbon and soil nutrients in each component. The results showed that with the reduction of the degree of desertification, the contents of SOC, N,P and K in each particle fraction presented gradually increasing trends in chorus. The nutritional contents associated with unprotected soil coarse-fine sand and very fine sand were more sensitively changeable in response to the desertification reversal. During the reversal of desertification, the contents of SOC, N, P and K associated with each particle fraction, as well as their enrichment factors, always have the tendency of silt + clay> very fine sand >coarse-fine sand. the above results suggested the increasing silt + clay contents played a crucial role in the nutritional storage. Along with the gradually increasing deposition of silt + clay during this reversal of desertification, the relatively stable SOC, N, P and K contents associated with silt + clay steadily increased, while the relative quantities of the unprotected particulate organic C, and N, P, K declined gradually. Thus the stability of SOC, N, P and K in the bulk soil was increased.