The cultivation of rice—the staple grain for more than 3.5 billion people around the world—comes with extremely high environmental, climate and economic costs.

This may be about to change, thanks to new research led by scientists at the University of Massachusetts Amherst and China's Jiangnan University. They have shown that nanoscale applications of the element selenium can decrease the amount of fertilizer necessary for rice cultivation while sustaining yields, boosting nutrition, enhancing the soil's microbial diversity and cutting greenhouse gas emissions.

In a new paper published in the Proceedings of the National Academy of Sciences, they demonstrate for the first time that such nanoscale applications work in real-world conditions.

"The Green Revolution massively boosted agriculture output during the middle of the last century," says Baoshan Xing, University Distinguished Professor of Environmental and Soil Chemistry, director of UMass's Stockbridge School of Agriculture, and co-senior author of the new research. "But that revolution is running out of steam. We need to figure out a way to fix it and make it work."

Part of what made the Green Revolution so revolutionary was the invention of synthetic, nitrogen-heavy fertilizers that could keep agricultural yields high. But they're expensive to make, they create an enormous amount of carbon dioxide, and much of the fertilizer washes away.

Most crops only use about 40–60% of the nitrogen applied to them, a measurement known as nitrogen use efficiency, or NUE, and the NUE of rice can be as low as 30%—which means that 70% of what a farmer puts on their fields washes away into streams, lakes and the oceans, causing eutrophication, dead zones and a host of other environmental problems. It also means that 70% of the cost of the fertilizer is likewise wasted.

Furthermore, when nitrogen is applied to soils, it interacts with the soil's incredibly complex chemistry and microbes, and ultimately leads to vastly increased amounts of methane, ammonia and nitrous oxide—all of which contribute to global warming. Furthermore, synthesizing fertilizer itself is a greenhouse-gas-heavy enterprise.