Engineered Microbes Race to Replace Some Chemical Fertilizer on US Farms

Making synthetic fertilizer uses large amounts of energy and is responsible for roughly 2% of global greenhouse-gas emissions, so a number of companies are betting that engineered microbes can take on some of that job instead. Seeding the soil around a crop's roots with beneficial microbes can help supply the plant with nitrogen, potentially cutting both fertilizer costs and emissions.

The air is nearly 80% nitrogen, but plants cannot use it directly because it does not react readily with other elements. Instead, plants rely on "fixed" nitrogen that has been converted into reactive compounds such as ammonia. Synthetic fertilizer supplies this through the Haber-Bosch process, which uses natural gas to make ammonia. In nature, some soil microbes perform this nitrogen fixation themselves, and legumes even house nitrogen-fixing bacteria in nodules on their roots.

The challenge is that fixing nitrogen is energetically expensive for microbes, and putting all their energy into it can stop them from growing. US startup Switch Bioworks is trying to solve this with what it calls a genetic switch: sections of DNA engineered so its microbes multiply into healthy colonies first, then switch on genes that trigger ammonia production once soil nitrogen drops to a certain level. "We have to reinvent fertilizer," said Tim Schnabel, the company's founder and CEO.

Switch is trialling its product in six US states and is two to three years from a commercial product, focused initially on corn, the most-planted crop in the US, which covered over 90 million acres in 2026. Schnabel said it is "too early to tell exactly how well this works in the field," though he noted that some treated corn plants already looked visibly healthier than untreated ones as of August. The company plans to harvest its test plots in late October or early November.

Pivot Bio, a company founded in 2011, has already put microbial fertilizers on millions of acres of crops and has expanded from corn into cotton, wheat, sorghum and barley. Its chief technology officer, Travis Frey, said growers are facing a "double whammy," with fertilizer costs rising even as commodity crop prices fall, and predicted biological fertilizers will "go mainstream" over the next decade. Dan Blaustein-Rejto, director of food and agriculture at the Breakthrough Institute, said such products have real potential to help farmers reduce emissions in "a quite hard-to-abate sector," but cautioned that field trials and independent verification of company data remain essential before such claims can be confirmed.