In recent decades, China has pushed the use of nitrogen fertilizer to help wrest as much food out of farms as possible, in part to stave off the famines of the past. Of course, such overuse of nitrogen results in air pollution and ocean dead zones—as well as, paradoxically, less fertile soil.

Now new research shows that by using just one third of typical amounts—presently as much as 600 kilograms per hectare—farmers could get the same or better results growing corn, rice and wheat, the main staple crops. The key is applying the fertilizer to seedlings rather than adding it to soil while planting, write Ju Xiao-Tang of China Agricultural University in Beijing and his colleagues in Proceedings of the National Academy of Sciences USA.

Even with reduced amounts of fertilizer, Ju and his team still produced 8,270 kilograms of rice per hectare compared to 8,012 kilograms per hectare with more fertilizer as is current practice. They also produced nearly 300 kilograms more wheat per hectare even when using 2.5 times less fertilizer. The new method would be both cheaper and prevent pollution, while maintaining the same yields that help feed more than 1 billion people, the authors note.

Translating research into practice, however, may not be simple: The challenge is in reforming the farming practices of millions of farmers who have been taught that more fertilizer means more food.

"Persuading farmers to limit fertilizer inputs is difficult because many of them still hold to traditional opinions that higher crop yield will be obtained with more fertilizers," the researchers wrote. But "only by reducing fertilizer nitrogen inputs can degraded environments be gradually restored."

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