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

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.

  1. Soil Armor, or Soil Cover

    “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.

  2. Minimizing Soil Disturbance

    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.

  3. Plant Diversity

    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.”

  4. Continual Live Plant/Root

    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.

  5. Livestock Integration

    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.

Regenerative Agriculture

“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.

Sources:  South Dakota Soil Health Coalition and Ohioline – Ohio State University Extension

  • Twenty years ago, U.S. farmers were feeding an average of 85 people each. Today that number has jumped to 155.
  • Over the last 20 years, U.S. corn production grew 80 percent, while:
    • Land use decreased by 37 percent.
    • Soil loss decreased by 69 percent.
    • Energy use decreased by 37 percent.
    • Emissions per bushel decreased 30 percent.
  • Growers raise 70 percent more corn per pound of fertilizer than 35 years ago.
  • Farmers today grow five times more corn than they did in the 1930s.
  • The average yield per acre has grown from 24 bushels in 1931 to 164 today. Contest winners have averaged over 600 bushels per acre.
  • Reduced tillage prevents erosion. Its adoption in South Dakota has increased from less than five percent in 1985 to 35 percent in 2010.
  • One acre of corn removes eight tons of greenhouse gases.
  • Thanks to ongoing innovations in seed, equipment and fertilizer technology, the amount of emissions per bushel generated to produce corn fell 30 percent in the last 20 years.
  • Farmers use Global Positioning System (GPS) technology to guide equipment so overlapping doesn’t occur.

Scientists have proven that corn grown in South Dakota actually adds carbon to the soil by virtue of the unique Northern Plains climate and increased use of minimum tillage practices by farmers.

  • Over the 25 years of the study, South Dakota corn average yields have increased at a rate of 2.29 bushels per acre per year.
  • Higher yields mean more crop residue left behind. The increased amount of residue has a significant impact in building soil carbon.
  • Our cooler Northern Plains climate plays a key role in the equation due to mineralization, a process by which organic matter and humus break down in the soil. When there are cooler temperatures, the mineralization rates are lower.
  • No-tillage adoption in South Dakota has increased from less than five percent in 1985 to 35 percent in 2010. Minimum and no-tillage production means there is more residue left behind in cornfields. Those practices also mean fewer trips across a field, resulting in even greater environmental benefits.

South Dakota farmers are protecting natural resources.

  • Advances in seed science, machinery and precision farming tools help farmers grow more with simplified weed control and reduced chemical applications.
  • One acre of corn removes eight tons of harmful greenhouse gas, more than what is produced by your car annually.
  • Because of innovative fertilizer application methods and frequent soil testing, American farmers grow 87 percent more corn per ounce of fertilizer.
  • Planting cover crops and/or moving to longer crop rotations allows farmers to naturally manage soil fertility, quality, water, weeds and pests – and improve farm habitat for wildlife.

Reduced tillage conserves soil.

  • Reduced or no-till planting conserves soil and water and reduces soil erosion and fuel usage.
  • No-tillage adoption in South Dakota has increased from less than five percent in 1985 to 35 percent in 2010.
  • Reduced tillage and other farm management practices have decreased soil erosion by 37 percent in 20 years.

South Dakota farmers protect water quality.

  • Farmers work hard to protect streams, ponds, rivers, lakes and wetlands. By keeping water edges in their natural state, we help control runoff and erosion and allow water insects, animals and fish to thrive.
  • Cover cropping helps reduce soil erosion.
  • Natural vegetation “filter strips” intercept and trap pollutants and soil from fields before they reach waterways.
  • Furrow alignment reduces the amount of runoff from rain or irrigation.
  • Diversion channels send runoff to safe areas and prevent excessive erosion.
  • Buffer strips and grass waterways in ditches capture sediments or nutrients and prevent erosion.

Drain tiling in a field is similar to drainage around your home — diverting water where it is not wanted. It’s a way to manage excess water and to keep nutrients in the fields. Tiling helps with:

  • Reducing storm water runoff and downstream flooding through absorption.
  • Reducing water damage to public roads.
  • Decreasing crop loss due to drowning.
  • Increasing soil surface temperatures, which helps seeds germinate.
  • Allowing plant roots to grow deeper into the soil so they can absorb more nutrients.
  • Providing enough oxygen for plant roots to mature properly.
  • Increasing the number of days available for planting and harvesting crops.
  • Improving soil structure by avoiding soil compaction and structural damage.
  • Promoting energy-conserving farming practices such as no-till and conservation tillage.
  • Reducing loss of sediment and nutrients.
  • Allowing for more efficient use of resources.