Abstract: Carbon stock of sweetpotato and soil respiration were investigated following different types of organic amendments, in order to lay a foundation for further research on carbon sequestration and emission effects of sweetpotato ecosystems. Fertilization experiments for sweetpotato-wheat rotation system were based on National Agricultural Experimental Station for soil quality in Xuzhou, Jiangsu Province. In 2023, five treatments were selected for this experiment: chemical fertilizers (CK), chemical fertilizers combined with wheat straw (ST), chemical fertilizers combined with biochar (BC), chemical fertilizers combined with organic fertilizer (OF), chemical fertilizers combined with biomass of green manure returning to the field (GF). This study mainly focused on investigating yield, above-ground biomass and carbon content of sweetpotato during harvest period. Further, net primary productivity (NPP) was estimated to characterize the effect of carbon sequestration of plant. Soil samples were collected during the harvest period to analyze the physicochemical properties and carbon fractions. Moreover, the rates of soil respiration were monitored during the reproductive period. The results were given as follows: 1) Compared to CK treatment, ST, BC, OF and GF treatments significantly increased soil total organic carbon (SOC) content, wherein ST and GF treatments significantly decreased soil dissolved organic carbon (DOC) content by 21.3% and 25.2%, respectively, while OF treatment significantly increased DOC content by 12.8%. 2) Carbon sequestration by vines have ranged from 1818.02 kg hm⁻² to 3811.72 kg hm⁻², and carbon sequestration by storage roots have ranged from 2718.69 kg hm⁻² to 4299.93 kg hm⁻² for each treatment. NPP in sweetpotato has ranged from 9559.16 to 14392.58 kg hm⁻². BC and GF treatments decreased NPP by 22.5% and 19.9%, respectively, OF treatment elevated NPP by 16.7% compared with CK treatment. Correlation analysis showed that carbon sequestration by storage root was mainly positively correlated with soil DOC content (P<0.05), and it was negatively correlated with the compactness of the subsurface layer (22.5−40.0 cm). 3) The cumulative emissions of CO₂-C were ranged from 5738.84 kg hm⁻² to 11257.23 kg hm⁻² during the growth period of sweetpotato among these treatments, wherein the OF treatment had the highest emissions. Compared to CK treatment, the cumulative amount of CO₂-C emitted from soil heterotrophic respiration significantly decreased and that emitted from autotrophic respiration significantly increased under the OF treatment. Regression analyses showed that soil respiration rate increased with water vapor flux and temperature. Spearman analyses showed that cumulative CO₂-C emitted by soil heterotrophic respiration was influenced by above-ground carbon content, soil water content and subsurface compactness, while the yield and carbon emission efficiency (CEE) of storage root were the main factors to influence the rate of soil autotrophic respiration. In summary, this study clarified the effects of returning different organic materials on carbon sequestration of sweetpotato, and the organic fertilizer application had the best effect, but at the same time, the cumulative CO₂ emission from soil respiration was also the highest. The drivers of soil heterotrophic and autotrophic respiration are different and need further attention. These results can provide the theoretical reference and scientific basis for the creation of green and low-carbon technologies for typical crops in the region.