Four threats to soil productivity
Living soil swarming with microorganisms requires quality care to maintain its productivity – just as healthy humans do.
For us, that may mean annual checkups, regular exercise, and a well-balanced diet.
The soil ecosystem requires a systems approach to management that is proactive instead of reactive, supports crop yield, and helps promote long-term productivity.
Bruce Waugh, a farmer in southeastern Minnesota, has applied this whole-systems management to his operation for 20 years. Waugh’s primary focus is beef cattle; his major strategies are rotational grazing and growing corn for feed silage.
His goal is to maximize the return on investment in land and equipment.
“The soil health journey is different for everyone and there isn’t a rule book,” Waugh says. “If you’re a row-crop farmer, you may gravitate toward cover crops, or if you’re a livestock farmer, you may be more interested in forage. Find what works for you.”
While there isn’t a one-size-fits-all approach, a combination of strategies will allow you to better reach your goals and improve your soil.
Jon Zuk, agronomist for WinField United, identifies four threats to soil health.
Lack of protection
Zuk defines protection as the barrier between the soil’s surface and the air. Without it, the soil is likely to erode and nutrients to run off in certain geographies or environments.
A living crop like cereal rye or a cash crop of corn or soybeans is a natural barrier, as is harvest residue.
Burning residue, tilling it under after harvest, or running choppers to break down standing stalks can take away protection and nutrients.
Reducing these practices is an easy change and doesn’t require any more investment in precious time and money.
Zuk recommends first evaluating different methods of residue management. Because every farm’s needs vary, consider the size and placement of residue, and then decide if tillage or other practices are right for your acres.
If you leave the soil alone in the fall and incorporate some tillage to prepare the seedbed in spring, you would be protecting the
soil with a cover all winter and avoiding excessive disturbance.
Tillage for tillage’s sake shouldn’t be the default. However, Zuk says some disturbance is good.
“Because tillage mixes the soil, in some cases it can help the microbes thrive,” he explains. “It reorganizes the population, puts them in a different environment, and helps them connect with each other.”
Zuk says the easiest first step is to identify the zones where excessive disturbance would be harmful: a slope, an area with poor drainage, or field with an outlying
“We can be smarter about where we till and know that some acres can still be managed with a tillage system,” he says.
The biggest contributors to soil organic matter are crop type and how long living roots are in the soil. That means a lot of the action happens below the surface.
“Those roots are what the microbes will feed on; it’s the most active part of the soil,” Zuk says. “Having big roots is truly important.”
limited roots and poor organic matter in permanent pasture. “With a relatively small investment of drilling in winter rye, I am hoping to reinvigorate pasture that has been overgrazed,” he explains.
Waugh says improvement doesn’t happen overnight. Yet, after two years of planting cover crops, he has seen subtle changes to the soil structure.
Limited roots are also tied to excessive disturbance when tillage causes layers of compaction.
Aggregate stability, or the granulation of soil structure, is a measure of soil health. If layers are compacted, that barrier will prevent roots from growing through the soil.
“With compaction, you’ll see less root mass, and less root mass means much less food for the microbes to survive on,” Zuk says.
Practice patience and don’t take your equipment into the fields until the soil is dry and warm.
“If there are poor weather conditions in the spring and you know you’re going to compact, just wait,” Zuk says. “Understand that farming has to happen eventually, but realize there are areas of your farm that likely can’t handle it.”
Zuk says 80% of compaction occurs the first time you drive over the fields. He recommends setting up a tram line or similar system that limits the surface area your equipment will run across. Also, run the combine as light as you can so there is less weight on the soil.
“Diversity means crop rotation,” Zuk says. “A crop monoculture isn’t ideal for soil health, but sometimes farmers are limited by the environment or markets as to what to grow. In that case, rotation even in a small percentage of the acres is good.”
Crop rotation will also benefit insect, pest, and weed management needs. Soybean aphid and other common insect infestations are more likely without a rotation. Instead of corn on corn, consider switching to a corn-bean rotation, plant a new crop with a different root mass, or introduce crops that grow at different times of the season.
“Sometimes farmers get comfortable in their system year after year, but if you change just one thing, that adds diversity to the system,” Zuk says.
He also suggests adding diversity in nutrient management, such as manure rather than commercial fertilizer.
Hauling manure can be expensive, but you might be able to partner with a neighbor who could provide the manure and help with application.
“Adding bacteria, fungus, and products containing humic, fulvic acid, or microbe mixtures can also help,” Zuk says. “We have to be careful with their application to be conscious of the farmer’s bottom line.”
Because so much activity happens below ground, however, it can be difficult to assess soil health.
As you start to make changes, Zuk’s advice is to use soil health tests that measure active carbon and aggregate stability. Those, in combination with a chemical analysis and micro/macronutrient analysis, will help you evaluate the progress and set benchmarks earlier.
Waugh’s advice is to try new things every year, which will help you find what works best on your farm and minimize the risks these four threats pose.