What Are Healthy Soils?
Challenges of Intensive Agriculture and Soil Degradation
Maintaining Microbial Populations
Building Soil Health for Long-term Success
After decades of focusing on inputs and maximizing production, agriculture today is placing an increasingly important emphasis on the role of the soil in producing a quality crop. The health of our soils is central to crop productivity, environmental sustainability, and long-term grower profitability. Achieving and maintaining that health is far from simple, however — and as with all progress in farming, growers are the key to success.
Building and maintaining healthy soils is a complex mix of biological, chemical, and physical factors. The end goal, however, is fairly straightforward.
“When you think of soil health, you think about the soil being able to produce healthy plants,” says Randy Huckaba, Director of Research and Product Development, Teleos Ag Solutions.
We now understand that process is driven in large part by the microbial life the soil harbors. These microorganisms perform critical functions — producing plant hormones, controlling pests, processing nutrients into plant-available forms, and improving soil structure. “For healthy soils, you're trying to encourage these soil microorganisms to flourish and to be there year-round as much as possible, Huckaba says.
Enhanced soil fertility is a logical connection to make when focusing on improving soils, but a fertile soil may not always be a productive soil, says Wesley Haun, Senior Agronomist, Tiger-Sul Products.
“A fertile soil is often referred to as the capacity of the soil to provide nutrients on crop demand, but at the same time may have some conditions that generally are not met to provide a productive soil,” he says. “Tiger-Sul offers a product that contains elemental sulfur. Elemental sulfur is not plant available. So, we depend upon microbial activity in the soil to convert elemental sulfur to sulfate which is plant available.”
Productive soils offer good aeration, sufficient drainage, biological activity, and favorable soil chemistry. “A productive soil is a healthy soil. It can sustain crop growth and it interacts with a number of other factors in the soil that drive a production system. With a productive soil, you can generally predict yield potential from year to year,” Haun says.
For healthy soils, you're trying to encourage these soil microorganisms to flourish and to be there year-round as much as possible.
Despite advances in our understanding of soil microbiology, growers face substantial obstacles in maintaining soil health. Even fertile soils can fall short of being productive due to compaction, poor drainage, and limited biological activity. These barriers often stem from mechanical operations and overuse. Soil compaction, in particular, appears to be a problem just about everywhere, because machines are getting bigger and heavier, says Sean Jacobs, Technical Sales and Marketing Representative, Agro-K.
“It doesn't really seem to matter if it's no-till, low-till, or regular agriculture — there are still problems with trying to open up the soil,” he says.
Haun agrees. “Compaction reduces soil aeration, and many of the bacteria and organisms that live in the soil require oxygen.” Without good drainage and airflow, microbial populations diminish, weakening the soil’s capacity to support a quality crop, he says.
That compaction didn't happen overnight, so you won’t be able to break it down overnight, Jacobs says. The key is making sure you are adding organic material back into the soil as you go.
“We still can go through the field with heavy equipment. We can still till, and we can still shank in stuff and do all the practices that we want to do that may have some adverse effect on the soil. But as long as we are opening up the soil, replacing the calcium, replacing the organic matter, and trying to maintain soil structure so we can have sufficient drainage and aeration, then the environment for healthy microbes to return and to flourish will be improved,” he says.
Another pervasive challenge is soil degradation through erosion, acidification, and nutrient depletion. Haun warns that overgrazing, monocropping, and excessive tillage accelerate these problems, often reducing the soil’s natural capacity to recover. “There’s a proverb: The soil will work for you if you work for the soil,” he says. “And that fits into the dynamics of a healthy soil. The driving force and the functionality of a healthy soil is the habitat that supports the ecosystem within that soil environment.”
Jacobs adds that prevailing agricultural practices, particularly in the US, have led to a chemical-solutions-first system over the years. A change in that mindset will help growers enhance their soil health, he says.
“If you were to look at yourself as an Olympic coach, and if you look at your plants as Olympians, are you going to give your Olympians antibiotics every single day, and only nutrients when it's convenient or affordable? The answer is no. You're going to do it the other way around, because you realize that if they have proper nutrition and they're healthy, they're less likely to get sick and to need antibiotics.
“We need to find ways to make these plants stronger and the soil stronger, so that we don't have to rely as much on the on the fungicides and the insecticides, and in turn, these products become more of an effective tool when you really need them.”
The goal of managing through all of these challenges is ultimately to build and maintain a healthy beneficial soil biology. That can lead to some potentially difficult decisions when a grower is focusing on the soil, and at the same time is facing a critical pest issue requiring a treatment that could impact the soil microbiome. In many cases, choosing not to fumigate to treat a nematode infestation in a field, for example, is simply not an option. Making decisions that find a balance between a critical crop protection treatment and concerns about damaging the soil microbiome are real. But they aren’t as dire as you might think, Huckaba says.
“We've done a lot of work across different locations, different crops, different application techniques from a soil fumigant standpoint. We've compared the fumigated soil to an untreated or non-fumigated soil, and taken samples across the course of the season. What we see is after fumigation, for most of the factors that are measured, there's little to no effect. There are a few where you may see some depression of [soil microbial] population and some shifts. But by mid-season, 6 or 8 weeks later, most of the time those populations or those effects are back to where they would have been without the fumigant, and certainly by the end of the season,” he says.
There are other ways to rebuild and support a healthy soil microbiome, as well.
A productive soil is a healthy soil. It can sustain crop growth and it interacts with a number of other factors in the soil that drive a production system. With a productive soil, you can generally predict yield potential from year to year.
“Microbes in the soil are important and irreplaceable,” Jacobs says. People understand that various chemistries we have to put out there may lead to disruptions with our microbial populations, he says. In those cases, microbial stimulants that serve as food for soil organisms can help.
“At Agro-K, we have products designed to support the growth and function of the soil’s native microbiology. When we feed the soil biology with these products, we encourage applying it near the start of an irrigation and watering it in deep,” he explains. “While the goal is to improve the health and function of the biology near the rootzone, achieving this is done by growing and strengthening the reserve microbial populations that reside at the edge and beyond of our day-to-day impact on the soil profile.”
Another — and one of the most practical steps to improve soil health — is the addition of organic matter. “If growers can grow a cover crop and incorporate that, they’ve added organic matter back into the soil,” Huckaba says, pointing out that organic material enhances microbial life, improves soil structure, and boosts water infiltration and retention.
Haun agrees, adding residue management, compost, and manure applications are critical components of a healthy soil ecosystem. He advocates a systems approach, promoting four foundational practices for long-term soil health: maintaining soil cover, optimizing crop rotation, minimizing tillage, and sustaining root growth for as long as possible throughout the year.
“Characteristics of a healthy soil include good soil drainage with well-drained soils; it has an active population of microorganisms as well as macroorganisms; it has good soil tilth; it has sufficient nutrients to support the crop on demand; and it has minimal pest issues. All of these factors contribute to the support and the functionality of a productive soil, Haun says.
Investing in soil health is like turning a battleship — slow and deliberate.
Despite the overwhelming evidence that building healthier soils is a win in just about every way for the farmer, the everyday realities of farming may make it tempting to slide back to old—and less expensive—habits. But growers need to think about the long-term benefits, even when short-term economics and logistical pressures push in the opposite direction.” Jacobs points out that “investing in soil health is like turning a battleship — slow and deliberate. Those who know it works realize that, ‘hey, it’s going to take me probably three years before I see any serious benefit,” he says.
With greater understanding and better tools, growers are beginning to ask the right questions about soil biology, nutrient balance, and sustainable management practices, Haun says. “Remember, a productive soil is a healthy soil.”
“I think we are coming back to the understanding that the soil is more important than we've been giving it credit for over the last 50 years, or maybe longer. The technology is catching up with where we think it needs to be going and we have faith that we can take real steps to help build healthier soils,” Jacobs says. “We can demonstrate it, and we're getting better at it.”
