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A recent review in Frontiers in Microbiology finds that heavy fertilizer use by rice farmers in China is limiting the ability of soil microbes to promote crop growth. The result is a greater dependency on artificial inputs, which threatens water and terrestrial ecosystems. But researchers find that integrating legumes can help mitigate these harms and help farmers use fertilizer more efficiently. Nitrogen fixation is a natural process that converts atmospheric nitrogen into a form that plants can use. While nitrogen is vital for plant health, too much can harm ecosystems, says soil health expert Yuting Liang of the Institute of Soil Science, Chinese Academy of Sciences. “In flooded rice paddies, excessive nitrogen can increase nitrogen losses and nitrous oxide emissions, affecting microbial processes involved in the nitrogen cycle,” Liang tells Food Tank. Liang notes that in contrast to conventional fertilizers, biological nitrogen fixation “supports a slower and more efficient nitrogen cycle.” But if the soil is already rich in nitrogen from fertilizers, microbes will respond by shutting the process down. “Many nitrogen-fixing microorganisms tend to reduce their activity because the need to fix atmospheric nitrogen becomes much lower,” she explains. This leads to a paradoxical feedback loop, the study explains...

The U.S. Department of Agriculture (USDA) recently announced a US$500 million investment to expand domestic mineral fertilizer production. While this funding aims to boost local manufacturing, environmental groups argue that the administration should focus on regenerative solutions like legume cover crops to fundamentally reduce the nation’s reliance on synthetic inputs. The USDA states the move will “improve supply chain resilience.” By increasing domestic manufacturing capacity, the agency hopes to shield American farmers from the extreme price volatility and geopolitical supply shocks that have plagued global fertilizer markets in recent years. But domestic fertilizer production heavily relies on fossil fuels. Environmental conservation groups like the Union of Concerned Scientists (UCS) and Natural Resources Defense Council (NRDC) argue that American agriculture can benefit more from incentivizing the adoption of regenerative practices like cover cropping rather than fertilizer expansion. According to the UCS, U.S. farmers apply 30 to 50 percent more nitrogen fertilizer than their crops can effectively absorb. A recent UCS report notes that this overapplication results in substantial environmental, economic, and public health-related costs—particularly in the U.S. Corn Belt. “When nitrogen runs off into water bodies, it creates algal blooms…algae multiply very quickly in the presence of nitrogen and use up...