[Influences of different irrigation amounts on carbon sequestration in wheat-maize rotation system]

Irrigation can influence greenhouse gas (GHG) emission and carbon footprint in agricultural production. In this study, annual GHG emissions (including CO₂, CH₄, and N₂O) were monitored with static opaque chamber and gas chromatography from a wheat-maize rotation system under different irrigation treatments in the Guanzhong Plain of China during 2014-2015. A total of four different irrigation treatments were conducted, e.g. W₀, W₁₂₀, W₁₈₀, and W₂₄₀, where the subscripts represented the irrigation amounts in mm. Net global warming potential (NGWP) and carbon footprint were used to evaluate the influence of different irrigation amounts on GHG emission and composition of carbon footprint of crop production. Compared with treatment W₀, wheat yield of treatments W₁₂₀, W₁₈₀, and W₂₄₀ increased by 31.3%, 44.3% and 33.7%, while corn yield increased by 9.9%, 22.6%, and 33.8%, respectively. Similarly, annual CO₂ emission increased by 22.2%, 24.3% and 15.1% and annual N₂O emission by 18.6%, 67.8%, and 91.5%, respectively, while annual CH₄ absorption decreased by 51.7%, 79.6% and 97.8%, respectively. The values of NGWP increased by 20.1%, 31.6%, and 31.4%, respectively. The carbon footprint of treatment W₁₂₀ was 19.1% lower than that of W₀, while W₁₈₀ and W₂₄₀ showed no significant difference. Treatments W₁₂₀ and W₂₄₀ increased carbon footprint per unit crop yield by 44.5% and 23.3%, respectively, while W₁₈₀ showed no significant difference. Considering both the economic and environmental effects of different irrigation amounts, we recommend the irrigating amount of 180 mm for the wheat-maize rotation system in the Guanzhong Plain of China for the purposes of water saving and carbon sequestration.