Engineered microbes aim to cut fertilizer use on farms

Fertilizer remains essential to crop production, but manufacturing it is energy-intensive and accounts for roughly 2% of global greenhouse-gas emissions. Companies developing microbial fertilizers want to replace part of that synthetic supply by using beneficial microbes around plant roots to fix nitrogen and feed crops.

Switch Bioworks is testing engineered microbes designed to grow into stable colonies before shifting into ammonia-producing mode. Its genetic switch could respond to nitrogen levels in soil, turning on genes that trigger ammonia production once levels fall. The startup is trialing its product in six US states and says commercialization is two to three years away, with an initial focus on corn.

Pivot Bio, founded in 2011, already has products used on millions of acres and has expanded beyond corn into cotton, wheat, sorghum, and barley. Researchers and industry experts say field trials and independent validation will be crucial, because lab results do not always translate to farm conditions.

Microbial fertilizers are not expected to eliminate synthetic fertilizer. Switch’s modeling suggests around 50% is likely the maximum replacement level, while its first product may replace about 25% of a farm’s synthetic fertilizer. Experts say other approaches will still be needed to reduce farm emissions and nitrogen pollution.