The Importance of Soil Health
What’s the big deal about soil? Isn’t it just a fancy word for dirt?
Unless you’re a farmer or a gardener, you probably haven’t thought much about soil. But farmers in South Dakota are increasingly thinking about soil and working to improve it.
We know there are more microbes in a handful of soil than there are people on earth, not to mention larger life forms, such as earthworms and beetles.
Soil as a Biological Community
“Managing the biological community that exists in the soil is really the future of agriculture,” says South Dakota Corn Director of Sustainability Jim Ristau.
“We’re just starting to understand the capabilities that this biological life can bring to crop productivity. We’ve kind of wrapped that whole concept up in the term, ‘soil health.’”
Focusing on soil health might be seen as a trend, but it shows no signs of letting up.
“It’s a little different than how we’ve farmed in the past,” Ristau says. “But it’s exciting. It leads to better yields. It leads to a better environment. It leads also to more money in the pocket because you’re more sustainable as a farmer, and you’re able to handle weather extremes.”
The Five Soil Health Principles
- Soil Armor, or Soil Cover
- Minimizing Soil Disturbance
- Plant Diversity
- Continual Live Plant/Root
- Livestock Integration
The Principles in Practice
Methods of implementing soil health principles are different for every farmer, based on many factors, such as geographic location, soil type and management practices.
“The first soil health principle is to keep the soil covered or protected,” Ristau says. Farmers do this by leaving crop residue in the field after harvest as opposed to plowing that residue into the soil. Another way to keep soil covered is through cover crops.
Farmers who leave crop residue in their fields need to manage the residue. “You can’t have too much or it causes problems,” Ristau says.
The second principle is minimizing soil disturbance. “Reducing tillage is part of residue management. We want to reduce the disturbance that tillage can cause, because that’s where this biological community lives. That’s their home. We want to keep those intact as much as we can,” he says.
Crop rotation and cover crops help farmers achieve plant diversity in their fields. “There are a whole bunch of different diets being fed to that diverse biological community,” says Ristau.
“It’s just like if people ate only ice cream. It’s probably not going to be very good for us. So we want to have a balanced diet, and that’s also true for the microbes.”
Just like people want to eat year-round, soil microbes want a continuous food source. A living root in the ground at all times allows for the life in the soil to access carbon year-round. The primary way for farmers to achieve this is through planting cover crops.
Ristau says, “Then the last principle is actually part of diversity—and that is to incorporate livestock, or the benefits that livestock can bring, like manure.” Grazing livestock helps the viability of cover cropping and residue management.
“Soil health is the basis for this new term we’re hearing, which is regenerative agriculture,” Ristau says.
“People are really interested in knowing how our food is grown and how our fuel is made. It is not harming our environment. This is really about healthy food, which translates into human health as well. People are conscientious of this,” he says.
But regenerative agriculture isn’t just about food. “If you take the 20,000-foot view, we’re taking more carbon out of the atmosphere and sequestering it underground through our production,“ says Ristau.
“We’re managing that carbon cycle, so we’re putting less into the atmosphere and putting more of it underground than what we’ve done in the past,” he says. “Agriculture has a huge potential ability to do this. It’s all wrapped around these soil health principles—managing for carbon and increasing organic matter in our soils.”
It’s a Microbe World
Back to the microbes in the soil, Ristau says they subsist on carbon from plants while plants thrive on the nutrients the microbes leave behind.
“There’s a mutual benefit. There’s a benefit to the plant. There’s a benefit to the bacteria,” Ristau says. “It’s just a constant life-and-death situation happening. Things are eating other things. Things are dying.”
“When the microbes die, that’s carbon turning into humus. It’s all decomposed microbial life that is turning that carbon into a solid. That ends up being humus and organic matter. That’s how we build the soil,” he adds.
Ristau concludes with a mind-bending thought. “Everything we’ve done in agriculture has managed the plant—what’s above ground that we can see,” he says.
“But when you start managing for below ground, the plants will be just fine. They’ll be just fine. That’s hard to wrap our heads around, but it’s absolutely the way this works.”
If you have questions about soil health, feel free to call the South Dakota Corn office at 605-334-0100.