WORTHINGTON - If one added up all of the living animals, insects and people on Earth and weighed it against all of the living microorganisms below ground, the microorganisms would weigh more.
It’s an important concept for crop producers to keep in mind as they work to maximize productivity from soil that has been worked and reworked for generations.
Soil health was at the forefront of a cover crops workshop Tuesday at Minnesota West Community and Technical College’s Worthington campus. Hosted by the Natural Resources Conservation Service and Nobles County Soil and Water Conservation District, the event drew more than 130 farmers and ag business professionals.
While still a relatively new concept to crop producers in southwest Minnesota, the use of cover crops is catching on as more farmers see the benefits of having cover on their soil year-round, and the ability of these crops to break up the hardpan in the soil and collect excess nutrients.
Kent Solberg, a livestock and grazing specialist with the Sustainable Farming Association, said growing cover crops in Minnesota has its challenges - and they’re not a silver bullet - but they are a tool to advance or improve soil health.
Solberg, who owns and operates a grass-based dairy near Verndale, has used cover crops for the past five years. He said they work best when used in combination with no-till, diverse crop rotations and grazing by livestock.
With the ability cover crops have to build glomalin and humus in the soil, add water holding capacity, increase fertility, improve soil aggregate structure and reduce the need for drain tile and irrigation, one might wonder why all crop producers aren’t planting cover crops.
“This is the toughest place to do it, but it’s not impossible,” Solberg said of Minnesota’s short growing season, and the popularity of the corn-soybean rotation particularly in southern Minnesota.
Solberg has diversified his crop rotations to maximize soil health benefits, using up to eight types of seed in his cover crop mix. The selection of warm and cool season grasses and broadleaf options can vary from one farm to another.
“There’s no one-size-fits-all or recipe for people to use,” he said. “Look at the soil health and what you want to improve.
“Diversifying the rotation is really what creates some of our greatest opportunities,” he added.
Solberg also spoke of the benefits of grazing livestock on cover crops, and reiterated the words of Dr. Duane Beck, who said one of the worst things farmers did for soil health was to remove livestock from the operation.
“Ruminant livestock are a walking vat of microbes,” Solberg said. “It’s also one of the most cost-effective means of recouping cover crop costs in the establishment year.”
He spoke of livestock producers who are grazing complex cover crops into December and January, and said the ability to use cover crops as a feed source has a “huge impact on your bottom line and how much hay you have to feed.”
Solberg told of one farmer who double-cropped acreage, raising oats and field peas ultimately harvested as hay for his cattle, and then seeding a diverse mix of brassicas and clovers. When the second crop grew tall enough, the cattle grazed the crop.
Ryes, clovers and brassicas are a good protein source for grazing cattle, and Solberg said the plantings are also a nice supplement to corn stalks late in the fall.
With so many farmers today only involved in crop production, Solberg said adding livestock with the incorporation of cover crops can be a win-win for established crop producers and young farmers.
“It may be a way to integrate a young producer interested in livestock production,” he said. “There are people around the country that are just crop producers and just livestock producers who are developing a cooperative agreement to graze cover crops and build soil health.”
Solberg spent a portion of his presentation talking about the success of cover crops in North Dakota. At Brown’s Ranch in 2012, the corn crop was more than 30 percent higher than the 10-year county average - and it was a drought year. No commercial fertilizers or herbicides were used, and the producer’s total cost for inputs was $1.44 per bushel. At harvest, the crop was sold for $6.98 per bushel.
“They’re profitable if corn really takes a hit,” Solberg said. “They didn’t get here overnight. They’ve been working at this for a while and they’re willing to share (what they’ve learned) with other producers to accelerate the process.”
While Solberg talked a lot about the benefits of grazing cover crops and introducing them to the crop rotation, Michael Lehman, a soil microbiologist at the North Central Agricultural Research Laboratory at Brookings, S.D., talked about the many benefits cover crops have on soil health.
One teaspoon of soil contains thousands of species of bacteria, millions of fungi, algae and protozoa and dozens of nematodes - and it’s important those are present, Lehman said.
“Microbes can help feed the world - they’ve been feeding us and supporting us for as long as we’ve been around,” he shared. “This isn’t anything new. It’s how we can take advantage of microbes to grow our crops and our livestock.”
The research lab in Brookings has a cornerstone approach to creating a biologically active soil, involving crop rotation, conservation tillage and cover crops.
Lehman said using cover crops in planting rotations helps protect the soil and takes advantage of free energy.
“If you don’t take advantage of this free energy, you are pumping carbon and nitrogen into your soil,” he explained. “You’re going to be enriching soil in a lot of ways with some free energy that would otherwise be wasted.”
While Lehman said the changes in the soil aren’t going to be instantaneous, over time producers will find much better soil properties.
Researches at the lab have conducted numerous studies not only about combinations of cover crops, but also about microbial health, nutrient uptake and residue removal.
In particular, Lehman said arbuscular mycorrhizal fungi (AMF) are nearly eliminated in most agricultural fields because of tillage and seasonal fallow. The mycorrhizae requires oxygen, and too much compaction “is no good,” he said.
Lehman said research at the lab has shown cover crops have a role in increasing mycorrhizae in the soil. AMF produces some of the cement that keeps the aggregates together, he added.
“With improved aggregation, you have improved soil structure and your soil acts more like a sponge - that’s a very good thing,” he added.
Nobles County Natural Resources Conservation Service District Conservationist Stephanie McLain told attendees that cover crops and how they’re being applied from North Dakota to Iowa are really different.
“The goal is to figure out what works for you - figure out your goals and try to make them happen,” she said.
Daily Globe Reporter Julie Buntjer may be reached at 376-7330.