Carbon footprint assessment of integrated paddy field management: irrigation, fertilization, and straw management

This is the authors' abstract. We don't add key points for this paper.

Irrigation, fertilization, and straw management are key determinants affecting the carbon footprint of rice production (CFP). To evaluate the synergistic effects among these practices, a three-factor experimental design was employed, involving straw return (R) vs no straw return (NR), continuous flooding (F) vs alternate dry-wet irrigation (D), and controlled-release nitrogen fertilizer (C) vs conventional fertilizer (U). Life cycle assessment was used to quantify the CFP per unit yield (CFPY) and area (CFPS) under different treatment combinations. Results indicated that straw return significantly increased both CFPY and CFPS compared to the NR treatment, whereas the irrigation D treatment reduced both more effectively than the F treatment. Furthermore, the fertilizer C treatment generally lowered both relative to the U treatment, with the reduction in CFPY being significant. Regarding synergistic effects, under NR conditions, both CFPY and CFPS in the D plots were significantly lower than in the F plots, regardless of fertilizer type. Under R conditions, however, only the combination of C and D yielded lower CFPY and CFPS values, which were significantly different from the other treatments. Among all treatments, NR-C-D, NR-U-D, and R-C-D exhibited comparable and significantly lower CFP. The CFP composition analysis revealed that embedded emissions from nitrogen fertilizer production and direct CH4 emissions were the primary contributors, with their trade-off regulated by irrigation and straw management. Overall, alternate dry-wet irrigation reduces CFP when straw is not returned, whereas the combined application of controlled-release fertilizer and alternate dry-wet irrigation is necessary to mitigate CFP under straw return conditions.