Abstract:In order to explore the effect of long-term application of different types of exogenous carbon on soil carbon storage and carbon sequestration potential of topsoil ash desert soil, the field positioning experiment, which included 5 treatment as no straw is returned to the field (NPK), NPK+ 1.5 t straw (NPKS), NPK+ 1.5 t organic fertilizer (NPKM), NPK+1.5 t cotton stalk carbon (NPKB1), and NPK+3.0 t cotton stalk carbon (NPKB2) was conducted. Soil collected from 2015 to 2021 was used as the research object. The correlation between soil bulk density (BD), organic carbon density (SOCD), organic carbon accumulation rate, organic carbon storage (SOCR), application years and organic carbon accumulation rate was analyzed. The results showed that (1) From the perspective of BD trend from 2013 to 2021, the application of NPKS, NPKM, NPKB1, and NPKB2 showed a consistent decreasing trend compared with NPK, with an average decrease of 1.84%, 0.86%, 5.03% and 6.66% compared with NPK, respectively. (2) Compared with NPK, soil SOCD increased by 12.21%, 11.04%, 24.14%, and 46.95% in NPKS, NPKM, NPKB1, and NPKB2 treatments, respectively, and cotton stalk carbon significantly improved soil SOCD. The cumulative rate increased by 73.16%, 66.95%, 133.52%, and 247.18%, respectively. (3) SOCR increased by 11.67% to 30.88% and 12.2%~33.24% in NPKS and NPKM treatments, respectively. NPKB1 and NPKB2 had the most significant SOCR improvement, with the highest improvement of 29.28% and 45.44% compared with 2013, respectively. Taken together, straw returned, cotton and organic carbon application is the effective measures to improve soil carbon of gray desert soil, in which addition of cotton carbon is more advantageous in short-term rapid increase soil organic carbon and carbon sequestration. Cotton charcoal itself contains rich nutrients. Long term cotton carbon addition increases soil carbon sequestration, improves soil fertility, alleviates the greenhouse effect, and is an effective way to achieve carbon neutrality.