[Evolutionary characteristics of soil organic carbon storage in soil plough layer under a cropland reclamation process in desert oasis].

The reclamation time was examined by combining field investigation and remote sensing image analysis in the Linze desert oasis area in the middle of the Hexi Corridor. Characteristics of soil organic carbon storage (SOCD) in cropland (0-20 cm) with different reclamation backgrounds were compared to understand the evolution trend of SOCD during reclamation. The SOCD of cropland (0-20 cm) varied from 2.41 to 32.97 t·hm, with an average of 17.22 t·hm. The ave-rage SOCD of cropland in saline-alkali land, Gobi and sandy land background was 19.36, 16.10, and 15.93 t·hm, respectively. The SOCD under three different reclamation conditions showed an increasing trend after cultivation. The cropland in sandy land and the Gobi background slowly increased after 20 years reclamation. The cropland in saline-alkali background showed a slowdown after 25 years reclamation. The SOC sequestration rates of the cropland under sandy land, Gobi and saline-alkali land background were 0.424, 0.485 and 0.811 t·hm·a, respectively. The SOCD were positively correlated with total nitrogen, total phosphorus, available nitrogen, and available phosphorus content, but had no significant correlation with available potassium and soil pH. In conclusion, the SOC sequestration rate in the saline-alkali land background was significantly higher than that in Gobi and sandy land background. However, SOCD were at a relatively low level after 30 years reclamation. Therefore, cropland management needs to be carried out for different reclamation backgrounds to improve land use efficiency and productivity in desert oasis.