Factors affecting soil organic carbon sequestration in rice fields: A meta‐analysis

Abstract Rice paddy soils are characterized by a high organic carbon content, and an understanding of the factors influencing soil organic carbon (SOC) is crucial for elucidating the global carbon cycle. A total of 559 observations from 121 papers were quantitatively analysed via meta‐analysis to characterize changes in the SOC content of paddy fields under different climate types, soil physicochemical properties and management practices. The results demonstrated that rice cultivation led to a significant increase in the SOC content by 24.68% relative to the initial content. pH, initial bulk density and average annual temperature (°C) were found to be positively correlated with changes in the SOC content of soils, and initial SOC, initial total nitrogen and latitude were negatively correlated with changes in the SOC content. Reduced tillage and no‐tillage significantly increased the SOC content by 46.51% and 31.48%, respectively. Compared with the control treatment (NS), the straw return treatment (SR) resulted in a 6.03% increase in the SOC content. The application of organic fertilizer (OM) alone, organic fertilizer plus chemical fertilizer (OM + CF) or biochar plus chemical fertilizer (CF + CB) increased the SOC content by 67.72%, 58.92% and 25.86%, respectively. Continuous flooding (W) effectively increased the SOC content by 46.37%. The SOC sequestration rate decreased with increasing initial SOC content, and the most notable increase in the SOC content was 87.93%, with the initial SOC content ranging from 0 to 0.5 g kg −1 . SOC sequestration is limited under conditions where the initial SOC content exceeds ca. 22.99 g kg −1 . This study contributes to the understanding of the response of rice SOC content to different management practices and climate types.