Assessing the Response Mechanisms of Elevated CO2 Concentration on Various Forms of Nitrogen Losses in the Golden Corn Belt

• Published in: Water resources research Vol. 60; no. 7
• Main Authors: Zhang, Yingqi, Han, Yiwen, Wen, Na, Qi, Junyu, Zhang, Xiaoyu, Marek, Gary W., Srinivasan, Raghavan, Feng, Puyu, Liu, De Li, Hu, Kelin, Chen, Yong
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01-07-2024
• Subjects: Carbon dioxide; Carbon dioxide concentration; climatic change; Corn belt; elevated CO2; Fertilizers; Leaching; Nitrates; Nitrogen; nitrogen losses; nitrogen management; SWAT‐CO2; Upper Mississippi River Basin; Water pollution; Water quality; Watersheds
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2024WR037226

Nitrogen (N) loss is a significant source of water quality pollution in alluvial watersheds. However, the mechanisms linking N loss and elevated CO2 concentration (eCO2) are not well recognized. In this study, we comprehensively calibrated the SWAT model equipped with a dynamic CO2 input and response module to investigate the response mechanisms between multiform N losses and eCO2 in a representative large‐scale watershed. Results revealed nitrate loss under eCO2 exceeding 100% in some upstream zones under the SSP5‐8.5 scenario (P < 0.05) compared to the constant CO2 concentration. This was directly related to the great increase in hydrological variables, which were the carriers of N losses, and the intensive inputs of N fertilizer. Results also found that nitrate leaching was greater than the other two processes for future periods, peaking at 309.3%, as compared to the baseline period. The findings suggested reducing fertilizer inputs by 10%–20% was promising, especially for reducing nitrate loss through runoff and leaching by up to 17.7% and 12.2%. This study explored the mechanisms of increased N loss in response to eCO2 and provided scientific evidence for early warning and making decisions to improve water quality at a large watershed scale.