Soil scientists say results from the field are inconsistent that bacteria, fungi and other natural products boost yields
Wired magazine doesn’t specialize in agriculture and food.
Yet, in September 2017, it published a piece with a provocative headline: “With Designer Bacteria: Crops Could one day Fertilize Themselves.”
The article argued that farmers are overly dependent on synthetic fertilizers, which is why companies and scientists are designing microbes (bacteria and fungi) that can deliver nitrogen to crops such as wheat, corn and canola.
Getting microbes to provide nutrients instead of adding fertilizer to the soil is definitely an appealing concept. It could also be lucrative because the global fertilizer market is expected to hit $245 billion by 2020.
That’s why venture capitalists and companies are spending tens of millions of dollars to develop bio-stimulants, which are biological products that enhance plant growth.
“Plant bio-stimulants contain substances or micro-organisms whose function, when applied to plants or the rhizosphere … enhance nutrient uptake, nutrient efficiency … and crop quality,” says the European Biostimulants Industry Council.
Boosting yield with a bacteria, fungi or a natural product is a nice idea, but results from the field are iffy, says Carl Rosen, a University of Minnesota soil scientist.
“I don’t discount anything until I see the data. So far, the data I’ve seen has been very inconsistent. I think that’s the bottom line,” said Rosen, who spoke at last month’s Manitoba Agronomists Conference in Winnipeg.
Rosen may be skeptical, but others are not. Dozens of players, from giants like Bayer to firms with a handful of employees, are competing to develop a breakthrough technology that can be sold to farmers around the world.
The consulting company Grand View Research has predicted that the global bio-stimulants market will reach $4.14 billion by 2025, up from $1.74 billion in 2016.
During his talk in Winnipeg, Rosen said firms are focusing on a number of bio-stimulants, including things like humic substances and seaweed extracts.
Most of the energy, and money, are flowing toward micro-organisms that stimulate nutrient uptake and plant growth. Soybean growers are already familiar with this idea because soybean seeds are inoculated with nitrogen-fixing bacteria.
However, other crops also benefit from soil micro-organisms. Private sector scientists are trying to identify, understand and commercialize microbes that stimulate growth in non-legumes such as wheat, corn and other big acreage crops.
“What they’re doing … is isolating soil (microbes) from that rhizosphere — that soil close to the root systems where you have this burst of activity due to all the (compounds) being exuded by the roots,” Rosen said.
“Companies are … isolating the microbes in that root zone and purifying those microbes.”
As an example, Evogene from Israel is working on a bio-stimulant for spring wheat. The company claims its product, a seed treatment still in development, can increase wheat yields by 10 to 20 percent. In 2019 it intends to test the seed treatment in the United States and then expand into Western Canada.
Scientists are studying a range of microbes, but two are drawing a lot of interest — plant growth promoting bacteria and plant growth promoting rhizobacteria.
“You have nitrogen fixation from these bacteria that are just free floating in the soil, so it’s not an association with soybeans or legumes,” Rosen said.
“Non-legume plants can benefit.”
Some of the bacteria can solubilize unavailable nutrients in the soil, such as phosphorus and zinc. Others release organic compounds that stimulate plant growth.
One example of a beneficial bacteria is Azospirillium. When it’s found near the roots of wheat, research suggests it can supply seven to 12 percent of the nitrogen for wheat plants.
“(But) these (bacteria) are native in most soils, so does it make any difference if you’re (adding) more?” Rosen said.
As well, adding bacteria in a lab doesn’t always translate to the field.
Rosen said field results have been inconsistent for a number of reasons.
For one, a teaspoon of soil can contain about one billion bacteria. Adding tens of thousands or even hundreds of thousands of bacteria to the soil is a drop in the bucket, and the new bacteria have to compete with native micro-organisms.
“Are Minnesota farmers really good at figuring this (all) out by themselves?” Manitoba Agriculture soil fertility specialist John Heard, asked following Rosen’s presentation.
“Or are they pressuring you to get in the testing business?”
Rosen said some farmers are using biological products based on anecdotal evidence.
“A lot of the potato growers will just go ahead and use this stuff,” he said, because potatoes are a high margin crop and farmers can afford $10 to $20 an acre.
For lower margin crops, such as corn or wheat, spending money on an unproven product doesn’t make sense, Rosen added.
Looking ahead, Rosen believes a game changing bio-stimulant is possible. However, it’s unlikely it will be used on every crop and every soil type.
He envisions a future where growers test soil samples to assess the population of micro-organisms on their farm. If a beneficial bacteria or fungi is missing for a particular crop, that species could be added to the soil. It will likely be a few years before such technology is affordable. Still, it may happen.
“You analyze the DNA in your soil, in the rhizosphere, and you look at all these different community structures and the soil microbiome,” Rosen said.
“There are a lot of companies and a lot of venture capital going into this segment.”