Environmental science: Crop switching can help to achieve more sustainable agriculture in China

Crop switching coordinated on a national scale may have the potential to contribute substantially towards China’s 2030 targets for sustainable agriculture development, according to a study published in Nature this week. The findings demonstrate the potential of crop switching to improve environmental sustainability without sacrificing crop production or farmer incomes in China.

China accounts for 19% of the global population, 19% of primary crop production and 12% of greenhouse gas emissions related to agrifood systems. China’s expansion in agricultural production has induced mounting environmental challenges, and the country is looking for strategies to develop a more sustainable agricultural system. Crop switching — the practice of growing different crops in the same area in succession and/or changing crop distribution — may be a promising way to improve agricultural sustainability.

Wei Xie and colleagues assess the potential of crop switching across China by combining high-resolution crop-specific data on yields and harvested areas with the environmental footprint of each crop (water requirement estimates, greenhouse gas intensity, fertilizer application rate and pesticide use) and farmer net income. They then established a model to simulate the contribution of crop switching to sustainable agricultural development across multiple dimensions and different regions. The study focused on 13 crops (including wheat, rice and soybean) that collectively account for 94% of China’s primary crop production and 90% of its harvested area. The results showed that when actions are coordinated and optimized at a national level, crop switching can help to achieve reductions in environmental impacts, including a 6.5% reduction in surface water and groundwater (so-called blue water) use, a 6.5% reduction in greenhouse gases and reductions in fertilizer use (8.1–9.8%, depending on type), while increasing farmers’ incomes by 4.5%. When actions are coordinated by separate government departments that each prioritize a single dimension of agricultural sustainability, crop switching may have better outcomes in some dimensions at the cost of tradeoffs for other objectives.

The model also identified some regional changes in distributions of specific crops that show benefits across multiple dimensions. For example, shifting away from maize and towards soybean, sugar beet and rice in the Northeast Plain would result in higher farmer incomes and reduce the overuse of fertilizer and pesticide. Overall, crop switching optimized at a national level could contribute 40% and 23% towards China's 2030 sustainable development goals of fertilizer use and pesticide use, the authors note.

The authors conclude that coordination at a national scale led by the central government is essential to avoid tradeoffs and realize multiple sustainability targets.