Synergistic water quality and soil organic carbon sequestration benefits of winter cover crops

• Published in: Journal of environmental management 2024-12, Vol.371, p.123104, Article 123104
• Main Authors: Zhang, Xuesong, Wang, Yiming, Lee, Sangchul, Liang, Kang, Zhao, Kaiguang, McCarty, Gregory W., Alfieri, Joseph G., Moglen, Glenn E., Hively, W. Dean, Myers, Daniel T., Oviedo-Vargas, Diana, Nguyen, Tam V., Hinson, Audra L., Du, Ling, Romeiko, Xiaobo Xue
• Format: Article
• Language: English
• Subjects: aquatic ecosystems; carbon sequestration; Chesapeake Bay; Cover crops; cropland; environmental health; environmental management; evapotranspiration; greenhouses; Maryland; Nitrate; nitrate reduction; nitrogen; Sediment; sediment contamination; sediments; soil organic carbon; stream flow; Sustainability; SWAT-Carbon; Tradeoffs; Water availability; water quality; water supply; water yield; watersheds
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2024.123104

Winter cover crops (WCCs) are promising best management practices for reducing nitrogen and sediment pollution and increasing soil organic carbon (SOC) sequestration in agricultural fields. Although previous watershed studies assessed water quality benefits of growing WCCs in the Chesapeake Bay watershed, the SOC sequestration impacts remain largely unknown. Here, we designed six WCC scenarios in the Tuckahoe Watershed (TW) to understand potential synergies or tradeoffs between multiple impacts of WCCs. Besides corroborating the nitrate reduction benefits of WCCs that have been reported in previous studies, our results also demonstrated comparable reduction in sediment. We also found that the six WCC scenarios can sequester 0.45–0.92 MgC ha−1 yr−1, with early-planted WCCs having more than 70% SOC sequestration benefits compared with their late-planted counterparts. With a linear extrapolation to all the cropland in Maryland, WCCs hold potential to contribute 2.1–4.4% toward Maryland's 2030 Greenhouse Gases reduction goal. Additionally, we showed that WCCs can noticeably increase evapotranspiration and decrease water yield and streamflow, potentially impacting aquatic ecosystem health and water supply. Overall, this study highlights the synergistic water quality and SOC sequestration benefits of WCCs in the Chesapeake Bay watershed. Meanwhile, sustainable adoption of WCCs into existing crop rotations will also require careful assessment of their impact on water availability. •The SWAT-Carbon model was used to assess synergies and tradeoffs of multi-dimensional environmental impacts of WCCs.•WCCs can reduce nitrate loading (38–71%) and increase SOC by 0.45–0.92 MgC ha−1 yr−1 on agricultural fields.•WCCs can also reduce water availability through more intensive water use (i.e., evapotranspiration).•In addition to the water quality and climate benefits, the impact of WCCs on water availability should be considered. [Display omitted]