The world's farms depend on synthetic nitrogen fertilizers to increase crop yields, but the production and use of these chemicals generates billions of tonnes of greenhouse-gas emissions every year. Now, scientists are making progress on a greener alternative: bioengineered bacteria. This approach takes a cue from natural bacteria that 'fix' nitrogen into a useful form and provide it to certain plants. Scientists are engineering genetic features into bacteria with the aim of enabling them to fix nitrogen for important food crops, such as maize (corn) and wheat, that don't have such natural microbial partners. In a comment published on 10 November in Nature Biotechnology1, researchers suggest that bioengineered bacteria could eventually replace up to half of synthetic fertilizers. The bacteria deliver nitrogen more efficiently to roots than synthetic fertilizers do, which could reduce greenhouse-gas emissions and nitrogen pollution of waterways. But this would require a slew of...
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