Abstract
Tillage practices influence the fate of soil organic carbon (SOC) by different intensities of soil disturbance. Few studies have examined soil aggregate structure and carbon pool from rice-wheat fields in eastern China. This study aims to evaluate the influence of tillage methods on aggregate fractions, SOC distribution, carbon storage, and carbon pool management index (CMI). A 5-year field experiment was conducted including 4 treatments: minimum tillage (MT), rotary tillage (RT), conventional tillage (CT), and conventional tillage with residue removed (CT0) in a rice-wheat system. Results showed that MT and straw retention are beneficial to the formation of >2000 μm aggregates. The organic carbon contents at 0~5, 5~10, and 10~20 cm depths increased when using MT, RT, and CT. Since the organic carbon was mainly distributed in macro aggregates, it increased by straw retention regardless of the tillage treatment used. There is a significant (P < 0.05) correlation between aggregates fractions and the content of organic carbon. Organic carbon stock at 0~20 cm depths increases by 15.6%, 14.5%, 13.4%, and -0.95% under MT, RT, CT and CT0, respectively. Compared with CT0, MT reduces the CMI while RT and CT enhance it. The CMI has a significant negative correlation with soil bulk density. Our results indicate that reducing tillage intensity, implementing straw retention, and especially their combined application can be effectively used to improve aggregates fractions and carbon sequestration in rice-wheat fields in eastern China.
