Agricultural trade between the United States and China is dominated by crops such as soybeans and maize that are shipped across the Pacific to feed livestock in China. A new study suggests that changing what is traded could bring substantial environmental and economic benefits.
Researchers found that shifting from exports of animal feed to exports of animal-derived foods could reduce global agricultural nitrogen loss by 38%, greenhouse gas emissions by 17%, and environmental damage costs by 32% compared with the current feed-based trade system. The change could also increase U.S. agricultural trade revenue by US$10.5 ± 2.4 billion.
The findings were published in Nitrogen Cycling on July 27, 2026.
"Our results show that the environmental impact of agricultural trade depends not only on how much countries trade, but also on what they trade and where production takes place," said corresponding author Xin Zhang. "A better designed trade portfolio, combined with improved nutrient recycling, could create economic opportunities while reducing the global environmental footprint of food production."
The researchers compared three scenarios using 2022 trade data. These included restricted U.S.-China agricultural trade, the current system dominated by U.S. feed exports, and a scenario in which animal-derived foods such as meat, milk and eggs are produced in the United States and exported to China instead.
The analysis shows that the existing feed trade already provides global environmental advantages. Compared with producing the same feed entirely in China, current trade reduces global nitrogen loss by about 32% and greenhouse gas emissions by 7%. This is partly because U.S. crop production generally has higher nitrogen use efficiency.
However, the current system also creates a nutrient recycling problem. Feed crops are produced mainly in the United States, while the animals consuming them are raised mainly in China. More than 40% of the nitrogen contained in imported feed is ultimately lost as manure in China, contributing to nitrogen pollution and limiting opportunities to return manure nutrients to the cropland where feed is produced.
Moving livestock production closer to feed production could improve this connection. Under the food-trade scenario, the researchers estimated that the amount of feed nitrogen required to produce the same quantity of animal products would fall because of higher livestock production efficiency in the United States. Global greenhouse gas emissions associated with the trade system would decline from approximately 57 ± 8 to 48 ± 7 million metric tons of CO2 equivalent.
The shift would not be environmentally beneficial everywhere. Increased livestock production could raise nitrogen losses and greenhouse gas emissions in several U.S. livestock-producing regions, including parts of Iowa, North Carolina, California, Texas and the Great Plains.
The researchers therefore examined additional strategies, including recycling plant-based food waste as animal feed and increasing manure recovery. Combining food waste recycling with improved manure management could substantially reduce the additional U.S. environmental burden associated with greater livestock production.
The study does not argue that the United States should simply expand animal-product exports to China. Instead, the authors emphasize that trade decisions should account for environmental consequences alongside prices, food security and economic interests.
The results suggest that agricultural trade policy can become an important tool for improving the efficiency of the global food system, particularly when trade strategies are combined with better nutrient recycling and manure management.
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Journal Reference: Wang Y, Gu B, Zhang X. 2026. Shifting U.S.−China trade from feed to food reduces global agricultural nitrogen loss and greenhouse gas emissions. Nitrogen Cycling 2: e024 doi: 10.48130/nc-0026-0011
https://www.maxapress.com/article/doi/10.48130/nc-0026-0011
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About Nitrogen Cycling :
Nitrogen Cycling (e-ISSN 3069-8111) is a multidisciplinary platform for communicating advances in fundamental and applied research on the nitrogen cycle. It is dedicated to serving as an innovative, efficient, and professional platform for researchers in the field of nitrogen cycling worldwide to deliver findings from this rapidly expanding field of science.
