Tennessee farmers have been transforming the landscape for decades with no-till farming methods, helping to restore the state’s soils. In fact, the University of Tennessee’s Research and Education Center at Milan has been a leader in this effort since 1981. The research conducted by UT AgResearch at Milan is known worldwide.
While no-till farming is the norm in Tennessee today, it hasn’t always been the case. “About four decades ago, West Tennessee was ranked as one of the top areas in the U.S. for the highest soil erosion rate,” says Don Tyler, retired professor for the University of Tennessee Institute of Agriculture. The average soil erosion rate for Tennessee at that time was 40 tons of soil per acre per year.
Unlike tillage, commonly known as plowing, no-till methods leave soils undisturbed, allowing crop residue to remain on the surface, protecting the topsoil from runoff. Seeds are planted in rows in the soil. In contrast, tillage leaves soil “bare” and highly susceptible to erosion.
Some soils across Tennessee are considered fragile, Tyler says, but West Tennessee’s are especially susceptible.
“The soils in West Tennessee are especially erodible because they are very silty soils,” Tyler says. “They are almost like talcum powder – very silty and easily moved by water if they’re exposed and tilled.”
As an example of how easily soil can erode with tilling versus no-till, Tyler says, “We have data that shows in till systems, one storm can result in the loss of more than 10 tons of soil per acre, whereas a no-till system right beside it with the same measurements may result in 1/10 of a ton loss. It’s a huge difference.”Today, Tennessee is a shining example of the no-till success, with up to 90 percent of the state’s farms using no-till practices, according to the USDA National Agricultural Statistics Service. This change was possible thanks to the assistance and innovation of the University of Tennessee Extension and UT AgResearch, within the University of Tennessee Institute of Agriculture, and Tennessee’s row crop farmers who saw the benefits and invested in the technology to make no-till a reality.
Tyler was one of the many team members enlisted to research and help Tennessee adapt its tilling ways that were having a negative impact on the land.
“With no-till, we’ve dramatically reduced the manmade accelerated soil erosion,” Tyler says. “A lot of the soil that we have now in the state would not be here if we did not go no-till. The soil was eroding at such a high rate, and there would be fields today that would have been abandoned if we did not make the change. We have many farmers now who have been completely no-till for 30 years,” he adds.
Huge Benefits
Farming in Dyer and Lauderdale counties, along the Mississippi River, Jimmy Moody experienced firsthand the positive changes that no-till methods brought to his West Tennessee farm.
Moody, who is in his mid-60s, farms on his own family operation and at Cold Creek Farms with a business partner, growing soybeans and cotton. Back when he used to till all of his land, he would need to burn crop residue, till soil and plow weeds. But since he took up no-till, he directly plants crops and controls weeds with advanced herbicides that were unavailable several decades back.
“When I was young, using no-till was unheard of,” Moody says.
No-till is good for the soil, reducing soil erosion and increasing organic matter in the surface soil. Plus, it encourages flourishing earthworm populations – which are a great indicator of soil health and create channels to flow water into soil and reduce runoff. No-till farming has economic benefits, too. “Farmers using no-till are minimizing their labor needs, the time it takes to actually farm, reducing fuel costs dramatically, and a lot of them can farm on a much larger scale than they would be able to otherwise, which has almost become necessary to survive,” Tyler says.
Moody agrees. “There’s no way that I could be farming on the scale that I am today without no-till farming,” he says.
Soil is filled with living, breathing, hardworking creatures – it’s a natural commodity more important than any cash crop. When soil is alive, it’s teaming with macro- and microorganisms, ranging the gamut from highly visible beetles and worms to microscopic viruses, bacteria, and fungi. Each of these soil citizens provides a service to the healthful functioning of the broader community.
Having lots of healthy and diverse organisms in the soil creates a self-sufficient cropping system that becomes less dependent upon synthetic fertilizers and pesticides.
The system itself produces fertility for robust plant growth, resistance to pests, and water-stable soil aggregates that enhance soil porosity to permit rapid water infiltration and to resist erosion.
In a nutshell, such a system produces resilient crops. In today’s uncertainty of climate, the need for plant resilience is growing more urgent by the day.
“The need to think about and work toward soil health is becoming extreme,” says Kris Nichols, a soil scientist-consultant from Kutztown, Pennsylvania. “Plants need resilience in order to withstand stressors such as adverse weather. One thing that you can count on is a continuing increase in the uncertainty and variability of climate.
“During the span of just one week here in Pennsylvania last winter, we had historic lows and historic highs in temperature,” she says. “We had a swing in temperature of 70°F. That doesn’t make any sense. Yet, it’s happened multiple times. How does a plant respond to such variability in conditions?
“We need a production system that is resilient,” she says. “A healthy soil that is alive with organisms keeps the system resilient. It does that by promoting diversity of life in the soil and above ground.”
Soil loss
Along with the growing need for resilience in cropping systems, there is a need for the kind of stable soil structure that resists wind and water erosion.
“We lose nearly 2 billion metric tons of topsoil annually in the U.S.,” says Nichols. “Most of that ends up in lakes, rivers, and estuaries. In the Gulf region, for instance, dredging is needed to remove the soil in order to keep shipping lanes open. Much of it is piled in that area, clogging the estuaries and exacerbating drainage problems.”
Eroding topsoil typically carries nitrates and phosphates from synthetic fertilizers with it, notes Nichols. These nitrates and phosphates end up in ground and surface waters, creating conditions such as the Dead Zone in the Gulf of Mexico.
“In some communities now in places such as the Midwest, it’s hard to get good drinking water without having to do costly filtration,” she says.
Limited supplies of phosphorus (P) fertilizers are yet another reason to build communities of healthy soil critters that can meet the plants’ need for P by extracting it from the soil and delivering it to plants.
“Globally, we’re running out of phosphorus fertilizer,” says Nichols. “Phosphorus fertilizer is mined and shipped into this country. A supply of about 20 to 30 years is about all we have left. Then we’ll have to figure out a different way to get it. Furthermore, when we apply it, much of it is wasted because, if it is not lost via erosion, it becomes readily unavailable in soil and can only be made available again by soil biology.”
These symbiotic relationships between plants and soil organisms permit natural pathways to fertility, disease resistance, soil stability, and whole-system resilience to weather variabilities.
All this while sidestepping much of the need for intervention with synthetic inputs.
When functioning in a healthful, whole-system framework, these relationships between plants and soil organisms, says Nichols, exist in an “elegantly complex” balance grounded in simple processes.
“We need to think about caring for the soil in the same manner that we take care of our own bodies,” she says.
With that in mind, following are the three cornerstones she suggests putting in place to grow life in the soil.
1. A healthy diet. “Carbon is the building block for every cell and every molecule for nearly all life on planet Earth,” she says. “Soil needs an influx of carbon through the process of photosynthesis occurring in living plants. It’s important to keep living plants growing in the soil.”
Diversity of diet is critical, too. “Feeding the soil a continuous diet of corn or wheat crops provides a lot of carbon, but it won’t be that healthy,” says Nichols. “Like us, the soil needs carbon in the form of protein or more complex carbohydrates. That’s why it’s important to have legumes and oilseeds in the system.
“All the different crops and crop types provide different compounds and different concentrations of these compounds for the soil life to eat,” she says. “Different consortia of different organisms consume different root exudates and crop residue from different plants.”
Growing diverse crops, cover crops, and perennials provides the soil life with the diverse diet needed to thrive and increase in population. Increasing diversity of cover crops can compensate for decreased diversity in cash crops.
2. Plenty of exercise. Providing the soil critters with work gives opportunity for exercise. “Their work involves breaking down and releasing nutrients in organic matter and minerals in the soil,” says Nichols. “In this process, they provide water and nutrients to the plants. Like us, they need a little bit of stress in order to best manage their food.”
A supply-and-demand payment system exists between plants and soil life. The application of synthetic fertilizers interferes with this delicate balance.
“Applying fertilizers outsources the work of the soil organisms,” says Nichols. “They buy carbon from the plant by giving the plant something.”
Outsourcing of their work happens, she says, when applications of synthetic fertilizers cause a lockdown in the plants’ natural mechanisms to work with soil organisms.
Thus, the soil organisms are bypassed, preventing them from having enough food to live on.
One example of this is roots that won’t allow arbuscular mycorrhizal fungi to colonize them.
3. A stable home. The soil organisms engineer for themselves homes in the soil known as soil aggregates. “The aggregates are like microbial villages, giving the fungi and bacteria a safe place to live,” says Nichols. "Tillage breaks apart the aggregates. It’s like taking a wrecking ball or a bomb and blowing up the village.”
The displaced organisms become more vulnerable to predatory organisms. “They were safe in their village, but now they’re exposed to larger organisms that eat them,” she says.
This predator/prey relationship is always going on in the soil, but the loss of soil aggregates permits an unhealthful balance of species.
Reducing tillage preserves habitat for the soil life, as does keeping the soil covered by residue or mulch.
“Even the impact of raindrops hitting the soil surface can blow up aggregates,” says Nichols.
Over the long term, growing life in the soil offers the priceless benefit of building a production system that is more resilient to wide swings in weather. Economic resilience could come hand in hand with healthier soil.
“You could expect to reduce costs, which could improve the bottom line,” says Nichols. “With a more resilient system, you could also expect to reduce year-to-year fluctuations in income.”
