For the last 100 years, ever since German chemists Fritz Haber and Carl Bosch figured out how to pluck fertilizer out of thin air with brute-force chemistry, farmers have relied on an imperfect product to make their plants grow: fertilizer. Production of the stuff burns through 3 percent of the world’s natural gas annually, releases tons of carbon into the atmosphere, and runs off into rivers and streams and aquifers. Relying on fossil fuels to grow food was never exactly sustainable.

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