Can engineered soil microbes reduce farms’ fertilizer needs?
Engineered microbes may help crops access nitrogen while reducing farms’ reliance on synthetic fertilizer, but field validation and practical limits remain.
Fertilizer supplies crops with the nitrogen they need to grow, but producing synthetic fertilizer consumes substantial energy and accounts for roughly 2% of global greenhouse-gas emissions. Researchers and agricultural technology companies are exploring whether engineered soil microbes can provide some of that nitrogen directly to plants.
The goal is not to eliminate synthetic fertilizer immediately. Instead, companies including Switch Bioworks and Pivot Bio are developing microbial products that could reduce how much farmers need to apply, potentially lowering both production costs and agricultural emissions.
Why crops need fixed nitrogen
Although nearly 80% of the atmosphere is nitrogen, plants cannot use atmospheric nitrogen directly because it does not readily react with other elements. Crops instead depend on fixed nitrogen, which has been converted into more reactive compounds such as ammonia.
Nitrogen reaches plants through several routes:
- Some naturally occurring microbes fix atmospheric nitrogen.
- Legumes form symbiotic relationships with nitrogen-fixing bacteria housed in root nodules.
- Manure and other biological fertilizers add nutrients to soil.
- Synthetic fertilizer supplies industrially produced ammonia.
Most synthetic ammonia is made through the Haber-Bosch process, which uses natural gas to fix nitrogen. Applying the resulting fertilizer has helped support global food production, but its energy demands and emissions have created pressure to find lower-carbon alternatives.
Microbial fertilizers aim to move part of the nitrogen-fixation process into the soil around crop roots. In theory, beneficial microbes can establish colonies near a plant and produce nitrogen compounds where the crop can access them.
The biological trade-off facing microbes
The central difficulty is that nitrogen fixation requires a great deal of energy. Microbes also tend to retain fixed nitrogen for their own proteins and survival rather than release it for a crop.
Engineering microbes to produce and release ammonia can therefore interfere with their ability to grow. Yet growth is essential for a practical agricultural product. Applying an already-large microbial population would be expensive and logistically difficult, so farmers need a smaller initial population to multiply around plant roots.
Switch Bioworks is addressing this conflict with a genetic switch. Genetic switches are sections of DNA that regulate whether particular genes are active. The company’s approach is designed to let microbes establish healthy colonies before activating genes involved in ammonia production and release.
Switch is investigating multiple ways to trigger that transition. Its leading option responds to nitrogen levels in the soil: When available nitrogen falls below a specified level, the microbes begin producing ammonia. This separates the colony-building phase from the more energy-intensive nitrogen-fixation phase.
Testing Switch Bioworks in cornfields
Switch is trialing its microbes in six US states and is initially concentrating on corn. More than 90 million acres of corn were planted in the United States in 2026, making it the country’s most widely planted crop.
According to founder and CEO Tim Schnabel, the company remains two to three years away from a commercial product. Switch expected to harvest plants from its current trials in late October or early November. As of August, some treated corn plants appeared visibly healthier than untreated plants, but the company said it was too early to determine the product’s field performance.
That distinction matters because promising laboratory results do not guarantee consistent outcomes on farms. Soil conditions, weather and other environmental differences can affect how well a microbial colony survives and functions.
Dan Blaustein-Rejto, director of food and agriculture at the Breakthrough Institute, emphasized that field testing is one of the final steps required before companies can make strong performance claims to farmers. He also noted the importance of independent trials, since results reported by companies can differ substantially from findings produced by independent researchers.
Pivot Bio takes microbial products to more crops
Pivot Bio is pursuing the same broad goal through a range of microbial fertilizer products. Founded in 2011, the company says its products have been used on millions of acres.
Its products can be applied in different ways. Some are added when crops are planted, while others are placed on seeds before they arrive at a farm. Pivot initially focused on corn but has expanded its work to cotton, wheat and small grains, including sorghum and barley.
The company’s technical priorities have also evolved. Pivot first worked on getting microbes to produce nitrogen regardless of whether they detected nitrogen in the soil. It is now trying to create fitter and more robust colonies that can perform across different environments, according to chief technology officer Travis Frey.
The economic case could be significant for growers. Fertilizer and seeds are among the largest costs on many farms, according to John Havlin, a professor in North Carolina State University’s department of crop and soil sciences. Reducing fertilizer requirements could therefore offer financial benefits alongside emissions reductions.
Microbes have a practical ceiling
Even successful microbial products are unlikely to replace synthetic fertilizer entirely. Switch’s modeling suggests microbes might replace no more than about 50% of current fertilizer use. Its first commercial product is expected to target a reduction of roughly 25%, according to the company.
Pivot has similarly said its products can replace approximately one-quarter of the fertilizer currently used. These projections suggest that biological products could meaningfully reduce nitrogen applications without removing the need for industrial fertilizer.
The limitations make several points clear:
- Microbial fertilizers should be assessed as partial replacements, not complete substitutes.
- Reliable performance across real-world growing conditions remains essential.
- Independent field results will be important for evaluating company claims.
- Other strategies will still be needed to cut fertilizer emissions and nitrogen pollution.
A promising tool, not a complete solution
Engineered microbes could give farmers another way to supply crops with nitrogen while reducing dependence on energy-intensive fertilizer. The technology is advancing from laboratory development into field trials and, in Pivot Bio’s case, commercial use across millions of acres. However, biological constraints and variable farm conditions mean its ultimate impact will depend on independently verified performance at scale.
Synthetic fertilizer is likely to remain part of agriculture for the foreseeable future. Microbial products may nevertheless become a useful component of a broader effort to control costs, reduce emissions and limit excess nitrogen use.
Original source: revew
Originally reported by revew.