Response of Soil Organic Carbon and Its Aggregate Fractions to Long-Term Fertilization in Irrigated Desert Soil of China

Abstract Irrigated desert soil samples in the Hexi Corridor of China were collected over a period of 23 years from a site where different fertilization methods had been used. Changes of soil organic carbon (SOC) and its water stable aggregate (WSA) size fractions were studied. The effects of various fertilization methods on the distribution of added organic carbon (OC) in different WSA size fractions were also analyzed. The results showed that the applied fertilizations for 23 years improved SOC concentrations and OC concentrations in all WSA size fractions compared to the non-fertilized treatment (CK). In addition, fertilization obviously increased the OC stocks of 2 mm, 0.25-2 mm and 0.053-0.25 mm WSA fractions, respectively. A significant positive correlation was found between soil C gains and OC inputs ( r =0.92, P