Where Do We Start Exploring?
By Carol Miller, Editor, American Vegetable Grower
As an industry, we know surprisingly little about soil health. It seems counterintuitive. Soil is so fundamental to growing, and it’s not a new-fangled technology. But we know only superficial aspects of soil health compared to our grasp on cell biology, a crop’s chemical reactions to fertilizer, or pests’ interactions with controls.
Traditional research relies on breaking down a topic to an extremely narrow focus, quantifying its elements, then moving on to another narrow slice of the topic.
Soil health, however, is complex. We don’t yet know how each microbe, mineral, or nutrient interacts with each other or with crops. You cannot easily isolate one element of soil without automatically tainting the study results, because you’re severing its link to the rest of the microbes or nutrients in the soil.
“Oftentimes, if you treat one aspect of soil health, it might have ramifications for another,” says Joey Blankinship, Associate Professor of Soil Ecology and Soil Health, University of Arizona. He is also a researcher for the Yuma Center of Excellence for Desert Agriculture (YCEDA).
Another difference in soil health research is the timeline.
“It requires more of a long-term perspective versus, say, the E. coli outbreak that happened a few years ago,” Blankinship says.
“That was an emergency, whereas soil health is more of a slow domino effect,” he says.
One major influence on soil health is how growing crops changes the soil profile from planting to harvest to the next planting. That means you need more than a lab. You need growers.
YCEDA, a public-private partnership in Yuma, AZ, is taking an inspired approach to tackling the issue. It brings farms and academia together. Its leadership and funding come from both, and grower insights keep all research grounded in the true needs of the industry.
YCEDA is launching the Yuma Soil Health Initiative to help them unpack which research to prioritize, then conducting the studies. Some will be multi-year, multi-institution projects, says its Interim Executive Director, Stephanie Slinski.
To get them started, YCEDA is hosting three gatherings by early 2024.
Step 1. First up is a grower workshop, taking place this fall, Slinski says. The goal is to identify what soil health means to desert growers and their operations.
“What is the benefit? And what will it take to integrate a solution? Because economics is really important,” Slinski says.
The local aspect matters, too, she says. Take the practice of allowing a field to recharge as it lays fallow or grows a cover crop. Fallow fields during the Arizona summer aren’t resting fields, however. They’re baked in the intense sun, and cover crops struggle in the unforgiving hot, dry climate.
"…My responsibility is to help figure it out and act as a gatekeeper of which products work and which ones don't…"
“How do you sustain soil biology when it's 120 degrees outside, and it's not raining?” Blankenship asks.
Step 2. Next up is a desert ag symposium on soil health, designed for both growers and researchers. That means presentations will be a mix of technical and non-technical to match attendees. The symposium will help the group understand what existing research has to say.
Step 3. Very quickly after the symposium the group will conduct what Slinski is dubbing knowledge mapping. Where are the gaps in research? What can be built on that will meet the needs of desert growers?
“Basically, we want to get a group of experts together and put them with representatives from the industry to discuss the output from the grower workshop and symposium,” she says.
Then the hard work starts — creating tactical teams, identifying funding, and developing the go-forward strategy document.
Blankinship says much of what the Yuma Soil Health Initiative researches must include growers.
“With so many variables in play, soil health research needs to take place in fields and not rely on labs and greenhouses alone,” he says. “Without that field experience, the risk of making the wrong recommendations is too high.”
Then there is the fairness factor.
“As we know, farmers in general have a tight profit margin. And it's hard for them to take these big risks and apply something that's relatively expensive across many hundreds of acres. My responsibility is to help figure it out and act as a gatekeeper of which products work and which ones don't,” he says.
Another challenge in soil health is a fundamental question: how do you measure health in soil?
In agriculture, Blankinship says much of the current understanding of soil health comes from the Midwest or eastern U.S.
“We have different ways of assessing soil health, just like your medical doctors might have different ways of assessing your health,” Blankinship says,
To further the medical analogy, think of how much our understanding of women’s health lags behind men’s. Since men’s hormones do not fluctuate to the same degree as women’s, they made much better test subjects because there were fewer variables.
We now know that women’s bodies do not behave the same way in some critical areas, such as heart health. A woman’s heart attack often doesn’t seem like a heart attack, because what we think of as the classic symptoms — pressure on the chest and pain in your arm — comes from studies on men.
Take cover crops. Yuma is the hottest and driest agricultural growing region in the U.S., Blankinship says. Many of the popular cover crops perform well in cooler areas. When heat mixes with irrigated fields, cover crops just melt and decompose too quickly in the desert to benefit soil, Blankinship says.
Blankinship has done work in several areas he’s keen to better understand about soil health:
Microbes vs. chemistry. Much of what we know about soil health lies in chemistry, especially when it comes to fertility. It’s also how we measure soil quality currently.
“I’m very interested in soil biology and really understanding the role of organisms in maintaining important functions,” Blankinship says.
How to manage the soil microbial community. Too often we think of microbes merely as pathogens, Blankinship says.
“You go to a soil health conference, and oftentimes half the vendors are trying to kill microbes and the other half are trying to add microbes,” he says.
Back to the human health analogy, this aligns with taking antibiotics to treat an illness then taking probiotics.
Better understand how organic matter builds in soil. A traditional way to build organic material is using cover crops, which Arizona struggles with.
Blankinship is exploring a few types that might survive desert conditions. Sesbania, for example, is a nitrogen fixer in the hemp family and can grow as tall as 14 to15 feet.
How to deal with heavy metals. Cadmium, for example, can be a problem in spinach crops.
“Cadmium is known to have many different negative human health effects. That's a big issue in California, as well,” Blankinship says.
What is soil health’s impact on nutrients? Blankinship plans to dig into the link between soil health and nutrient content in crops. Since farmland is unlikely to expand much more and our population continues to grow, an important measure of crop success will be nutrient loads. As a result, he sees a future where growers need more than yield counts.
“How much magnesium do these crops have? How much vitamin C per gram of leaf tissue? Maybe since I have kids, I think this human nutrition component is so key,” Blankinship says.
Understanding the impact of salinity. In the desert growing areas, irrigation water is adding salt to soil. It creates a dynamic where the more growers conserve water through drip, the more salt intensifies. Growers need to occasionally water fields enough to flush the salt down past the root zones.
The Yuma Soil Health Initiative is taking a holistic approach to the issue.
“It's not enough to have one project on salinity management, one on nutrients, one on pathogens or food safety. it requires that we think more strategically about the entire system,” Blankinship says.
For one, we need teamwork rather than competition, to increase the amount of complementary work, he says. Soil health is never one measurement. It requires really thinking broadly about issues and the constraints.
“The end goal isn't always how many publications you produce. And it's not necessarily about just other scientists reading my work. Instead, how does this research connect to other work out there? So, I think that we need more scientists working together.
One way the Soil Health Initiative will follow traditional research is in identifying benchmarks.
“When you measure something in your field, you need to know how that compares to what's normal. To what's achievable. We need to know what a normal range is. What's low? What's high? What can you do to change that? And which is moveable?” Blankinship says.
The only way to achieve that, he says, is by more effectively working together, from government to academia and growers.
