Cover crops—crops incorporated during the transition period between the growth cycles of two cash crops—have emerged as a promising tool to support more sustainable agriculture. They offer various benefits to agroecosystems through surface coverage and crop diversification, including provision (e.g., food and feed supply), regulation (e.g., carbon (C) storage and climate mitigation), and support (e.g., soil stabilization and erosion control). However, their implementation can sometimes come with trade-offs, such as increased greenhouse gas emissions, particularly if not adapted to local conditions or long-term strategies.

In a new study published in Nature Communications, an international team of researchers led by Dr. Tianyi Qiu (China Agricultural University and the Institute of Atmospheric Physics, Chinese Academy of Sciences), and including CSIC and CREAF researcher Prof. Josep Peñuelas, analyzed over 2,300 field observations from around the world. Their goal was to evaluate the global effects of cover crop practices on five key agroecosystem services: crop yields, soil organic carbon (SOC) stocks, soil structure, and emissions of nitrous oxide (N₂O) and methane (CH₄).

Their findings confirm that cover crops, in general, contribute positively to crop productivity, carbon sequestration, and soil stabilization. However, the researchers also observed a significant increase in greenhouse gas emissions—by 29.5% for N₂O and 42.3% for CH₄—under certain practices. These trade-offs highlight the need for optimized management strategies.

The study proposes a clear path forward: the greatest benefits occur when cover crops are used for more than five years, include a mix of legume and non-legume species, are terminated about 25 days before the main crop is sown, and are combined with climate-smart practices such as no-tillage and mulching of crop residues. Under this optimized scenario, researchers estimate a potential annual increase of 97.7 million metric tons in crop production, 21.7 billion metric tons in carbon dioxide sequestration, and a reduction of 2.41 billion metric tons in soil erosion.

“Cover crops have a double-edged effect,” explains Dr. Tianyi Qiu, lead author of the study. “While they clearly support multiple ecosystem functions, without careful planning they can also lead to unintended environmental impacts. Our findings show that long-term, well-designed cover crop systems can help balance these effects and contribute meaningfully to food security and climate mitigation.”

The study also highlights that optimized practices can deliver the greatest benefits in areas facing the most challenging environmental and socio-economic conditions—such as degraded soils, low fertility, or limited access to chemical fertilizers. In this context, cover crops may help reduce inequality in agricultural productivity between developed and developing regions.

“Nature-based solutions like cover crops are essential to achieving a more sustainable and resilient food system,” says Prof. Josep Peñuelas of CREAF and CSIC. “By tailoring practices to specific environmental conditions and promoting long-term strategies, we can maximize their benefits and contribute to global sustainability goals, particularly in vulnerable regions.”

The authors call for greater investment in farmer education, local adaptation strategies, and international cooperation to enable the broad adoption of optimized cover cropping. They also advocate for new incentive programs and policy mechanisms that support long-term ecological benefits.

Reference
Qiu, T., Shi, Y., Peñuelas, J., Liu, J., Cui, Q., Sardans, J., Zhou, F., Xia, L., Yan, W., Zhao, S., Peng, S., Jian, J., He, Q., Zhang, W., Huang, M., Tan, W., Fang, L. 2024. Optimizing cover crop practices as a sustainable solution for global agroecosystem services. Nature Communicactions 15, 10617. Doi: 10.1038/s41467-024-54536-z. https://doi.org/10.1038/s41467-024-54536-z