Of the hundred-million-plus tons of fertilizer sprayed onto farm fields each year, much of it eventually ends up polluting the air or flowing into water, where it can cause toxic algae blooms like the green slime seen in Florida. One startup is helping farmers begin to replace standard chemical fertilizers with microbes that help them grow without the bad side effect of pollution.
The first product, designed for corn farmers, is a microbe-filled liquid that can be added to fields using standard equipment when a farmer plants seeds. “Our approach is to start with what’s naturally there in the soil and the roots of the plant today and tap into that potential,” says Karsten Temme, cofounder of the startup, called Pivot Bio. Like chemical fertilizer, the microbes help the plants access the nitrogen they need to grow.
“These microbes are breathing in nitrogen gas from the atmosphere and then convert that into ammonia–that’s a form of nitrogen that plants can use as a building block for DNA and protein,” Temme says. “The difference from fertilizer is that these microbes are able to spoon-feed that plant its nitrogen every day.”
Fertilizer is typically added to fields in large quantities since it isn’t possible to drive a tractor through a field once plants are growing; if it rains, much of the fertilizer can wash away. Some of it can turn into greenhouse gases. “All of that inefficiency means about half of fertilizer globally turns into pollution before the plant has a chance to utilize it,” he says. That also wastes the energy used to make fertilizer (by some estimates, as much as 5% of global energy use). The company has calculated that its microbes take about 200 times less energy to produce and transport.
Right now, the first product supplies 25 pounds of nitrogen per acre–for corn farmers, that’s only about 20% of the total nitrogen needed, so farmers use it in combination with chemical fertilizer. But given the huge volumes of fertilizer that are used, that reduction has an impact. Pivot Bio estimates that if the product was used on 35% of corn fields, it would cut nearly 20,000 metric tons of nitric oxide emissions, or the equivalent of taking 1.5 million cars off the road. It could also potentially prevent as much as half a million metric tons of nitrates from polluting water.
In national tests in 2018, farmers grew more corn per acre by using the microbes than when they used chemical fertilizer alone. That increase in yield, along with knowing that the product won’t wash away in the rain, gives farmers a financial incentive to switch. The company now plans to bring the product to corn farmers elsewhere, and is developing other versions for wheat and rice; the three crops consume roughly half of the world’s fertilizer. It’s also developing new generations of its microbes for corn that can replace a greater percentage of fertilizer.
“I 100% believe that we’ll have a full replacement for fertilizer in a very short amount of time,” says Temme. “It’s really because that’s how the entire world worked before we had fertilizer. All we’re trying to do is go back to what has naturally evolved in this relationship between microbes and plants.”