Trade-offs between crop production and GHG emissions following organic material inputs in wheat-maize systems.

The recycling of agricultural organic wastes into fields is as a viable strategy to increase crop yields while mitigating pollution and fostering environmental protection. However, the effects of various organic amendments on crop productivity and greenhouse gas (GHG) emissions need to be comprehensively assessed. Thus, in this study, we conducted a field experiment from 2019 to 2022 in the North China Plain, investigating the effects of recycling straw, pig manure, and biogas residue and applying chemical nitrogen fertilizer as a control on crop yields, GHG emissions, and the synergistic effects of yield benefits, agricultural operational costs, and environmental benefits in a wheat-maize cropping system. The results revealed a disparity in the effects of different organic amendments on crop yields. Compared to chemical fertilizers, pig manure significantly enhanced yield and stability (5.82 %), whereas straw significantly decreased the yield of wheat and maize. The addition of organic amendments stimulated GHG emissions, with treatments involving pig manure resulting in the highest emissions, which significantly increased by 39.87 % compared to those of the control. Straw, manure, and biogas residue increased the greenhouse gas intensity (GHGI) of the cropping system. Biogas residue and straw applications increased the in GHGI during the wheat season, whereas the application of manure significantly increased the GHGI during the maize season. The synergy indices for yield - agricultural activity cost and yield - GHG cost during the wheat season and across years for pig manure incorporation both had a value of 10, indicating its advantage in average crop yield during the wheat season and throughout the year. The findings of the study indicated that the incorporation of organic materials not only achieves high yield benefits but also maintains lower GHG costs and agricultural activity costs. Although soil GHG emissions increased, pig manure incorporation remained the optimal nitrogen application strategy when the comprehensive factors of yield benefits, agricultural activity costs, and GHG costs were considered.