CEO Tim Schnabel says his company’s first product could replace 25% of a farmer’s conventional nitrogen fertilizer
Switch Bioworks has begun field-testing engineered microbes designed to produce ammonia directly on corn roots, a technology the company believes could eventually replace a meaningful share of conventional nitrogen fertilizer.
CEO Tim Schnabel told Energi Media that the company received permits from the US Environmental Protection Agency and Department of Agriculture to conduct its first corn field trials this year.
The trials represent an important transition for a technology that has so far demonstrated its effectiveness primarily in laboratory conditions.
“It works in the lab so far,” Schnabel said. “We have to wait to see when it works in the field.”
Modern nitrogen fertilizer is generally produced through the Haber-Bosch process, which uses natural gas and substantial amounts of energy to manufacture ammonia in large industrial plants.
Switch aims to move part of that production process onto plant roots.
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Plants are naturally colonized by microbes. Switch genetically engineers selected organisms to grow on the roots and eventually release ammonia that the plant can absorb as fertilizer.
The principal biological challenge is that microbial growth and ammonia production both require considerable energy.
Schnabel discovered during his doctoral work at Stanford University that microbes engineered to release ammonia often stopped growing. Without growth, farmers would have to apply impractically large quantities of microbes rather than relying on the organisms to reproduce on plant roots.
His proposed solution was a genetic switch that allows the microbes to perform the two tasks sequentially.
The microbes initially use their energy to grow and colonize the roots. A DNA sequence programmed to track time then activates several weeks into the growing season, shifting the organisms from growth to ammonia production.
Schnabel said the technology represents a level of complexity not previously permitted for the field release of genetically engineered microbes.
The current trials will test how well the organisms colonize corn roots, whether the switch activates at the intended time and how effectively the microbial community supplies nitrogen to the plant.
Switch is developing a team of different microbial species rather than relying upon one organism.
Schnabel estimated that supplying the nitrogen needs of one corn plant could require approximately 100 billion microbes. The company is therefore testing combinations of organisms that can coexist without competing with one another.
It has not yet determined whether a successful product will require five species, 10 species or another combination.
Switch expects to continue improving the microbes as field data becomes available. Schnabel said artificial intelligence could eventually accelerate the design of genetic switches and microbial teams, although the company does not yet possess the large datasets required to train advanced models.
The company hopes to commercialize its first product within two to three years.
Schnabel said the initial product could replace approximately 25% of the nitrogen fertilizer applied by a farmer. Its value would vary with fertilizer prices, but he estimated that it could provide between US$25 and US$50 in value while eventually costing Switch about US$1 to manufacture at scale.
The technology could also reduce farmers’ exposure to fertilizer-price volatility caused by natural gas prices and geopolitical disruptions.
Switch is developing products for markets beyond the United States. A project supported partly by the Gates Foundation and King Philanthropies is examining microbes suited to corn production in Kenya and Nigeria.
Rather than exporting a US product, researchers are identifying organisms that already perform well in local soils, engineering them and returning them for testing.
Switch has also applied for permission to conduct field trials in Brazil, which Schnabel described as a large agricultural market with significant interest in biological products.
The company is initially concentrating on nitrogen, but Schnabel said the same genetic switching platform might eventually be applied to phosphorus or other agricultural products.
The broader objective is to reduce the dependence of global food production on fossil fuels and centralized fertilizer supply chains.
“Fertilizer produces food for four billion people today,” Schnabel said. “We cannot have the basis of our food chain dependent on fossil fuels.”
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