“I knew about this corn for a long time, but there was no way to approach it,” says Alan Bennett, University of California professor. “All of a sudden, through advances in DNA sequencing technology there was an aha moment that we can do this now.”
They’ve found that the corn can generate somewhere between 30%and 80% of needed nitrogen from this unique genetic trait. Now researchers are seeing if that ability can be transferred, replicated, or improved in other varieties of corn.
“The microbes are everywhere, and you need to have the right genetics in order to attract and harbor those microbes in a supportive environment,” Bennett says.
Bennett isn’t sure synthetic fertilizer use can go to zero, but cutting it in half could be a huge win for farmers around the world.
“The gains will be economically important in the United States, but they'll be dramatically more significant in places like Africa, where they may not have the option of synthetic fertilizer,” Bennett says.
Fertilizer Market Projected to surpass USD 240 -Bn by 2030
EXCRETE TO SUCCESS
At Washington State and Wisconsin, university researchers are busy engineering nitrogen-fixing bacteria called Azotobacter vinelandii as a replacement for traditional fertilizer.
“The bacteria fix nitrogen all the time (even in the presence of synthetic fertilizer) but depending on how we manipulate the genes we also end up with bacteria that can excrete ammonia in really large quantities,” says Florence Mus, assistant research professor at Washington State University.
Mus and team used gene editing to engineer the bacteria. They’ve also found a way to regulate the amount of ammonia produced knowing some crops need more fertility than others.
“Different crops have different nitrogen needs so we can customize the amount of ammonia a bacteria will excrete for a specific plant,” Mus says.
When asked about a future without synthetic fertilizer, Mus says it’s possible.
“We still have some work to do, but bacteria are already being used as biofertilizer in the cells we have engineered,” Mus says. “So, I think it's doable.”
HOW MULCH MORE
Cotton growers in certain areas of the country may be able to go without needing synthetic fertilizer right now, says Nicholas Basinger, University of Georgia’s Department of Crop and Soil Sciences.
“In a cotton crop we can replace all of the nitrogen that we need,” Basinger says. “We only need to supplement with P&K.”
He’s part of a team that has been studying the benefits of living mulch. While he’s a weed scientist and has seen significant benefits from a living, growing mat of Durana White Clover, there are also fertility benefits from the nitrogen-fixing legume.
“We know that the perennial living mulch will provide about 100 lb. an acre of nitrogen,” Basinger says. “One thing we don't know is exactly when or how all of that N is released in cotton. In corn, it’s a slow-release from planting on into the growing season as the corn shades out the living mulch.”
Seeded as a cover crop in the fall, at spring planting furrow strips are killed ahead of the planter. The clover between the rows continues to feed the seedling's roots. Basinger says the biggest limiting factor to wide adoption is water.
“Some of the trade-offs we have with this system is it has to be in the South and on irrigated land,” Basinger says. “Yes, we get weed suppression, yes, we get our nitrogen fixation, but it's not without the cost of competition for water resources.”
WHAT’S OLD IS MANURE AGAIN
Biological innovations are pouring into the industry from all corners of the globe, but Purdue University agronomist Tony Vyn says don’t forget the classics.
“I do not see a future without synthetic fertilizers,” Vyn says. “I do see a future using more biologicals and preferably while we’re also making much better use of manure and manure-based fertilizers.”
Nitrification inhibitors and nutrient monitoring have helped to keep manure a serious contender. He advocates for focusing on the 4R’s, using legumes, organic matter and soil health. However, Vyn is excited about the incremental improvements seed companies are making in nitrogen use efficiency.
“Modern hybrids are capable of capturing more of the nitrogen applied,” Vyn says. “How much fertilizer nitrogen did you put on the field and how much nitrogen are you removing from the field. Those nitrogen harvest index numbers are improving every decade.”
