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Keep Your Topsoil
At a North Dakota soil health field day, Jodi DeJong-Hughes, University of Minnesota Extension crop and soils educator, jestfully opened the event with a big thank you to that state’s farmers.
That’s because they send some of North Dakota’s best topsoil to Minnesota. Although the wind may have delivered it, she focused on what farmers were doing to cause it.
“We always think of wind and water erosion,” she told them. “One thing we never think of is tillage erosion.”
It’s not just a North Dakota issue. She illustrated the point with two photos of a west-central Minnesota county road ditch. One showed heavy snirt (dirt on snow) next to a field that had been tilled aggressively (less than 25% residue). Meanwhile, a pristine-white ditch flanked a field just down the road where the farmer left 45% crop residue.
DeJong-Hughes was inspired to do some digging herself. If farmers aren’t overly concerned about destroying soil structure or losing topsoil, she wondered if they might be interested in knowing how much money soil loss can cost them.
“I wanted to show how much N, P, and K (nitrogen, phosphorus, and potassium) is moving with the soil into the ditch,” she says. She took six samples of snirt from different ditches across western Minnesota and had it analyzed.
Topsoil losses ranged from 1.6 tons to 33 tons per ditch acre. (An acceptable soil loss is 5 tons per acre – the thickness of a dime.)
Nutrient losses also ranged wildly, from 10 pounds to 172 pounds per ditch acre of total N losses. This was on top of P and K losses.
“If you add up the averages, it’s about $55 per acre of N, P, and K,” DeJong-Hughes says. “The organic matter came back about 4.1 or 4.2 (a good organic-matter level). So, it’s your best soil that you are losing.”
Fortunately, there are solutions.
Set up for erosion
To be fair, the producers in eastern North Dakota and western Minnesota face extra challenges. The Red River Valley is one of the three worst areas in the U.S. for wind erosion because of its flatness and soil type.
“Anytime you have more than a 13-mph wind over a flat surface, you can have wind erosion,” DeJong-Hughes says. That wind speed is fairly typical for the region. Plus, the soil has a high clay content.”
Clay is made up of microscopic particles, much smaller than sand and silt. “The smaller the particle, the easier it is to move,” she notes, referring to a photo of a gray fog of clay particles nearly obliterating a grain elevator in the background. That makes clay extremely vulnerable to wind erosion when it is dry.
Windbreaks and other practices have greatly reduced wind erosion since the Dirty 1930s when North Dakota soil blew as far as New York and the Atlantic Ocean.
“Minnesota actually has higher wind erosion than North Dakota,” she adds.
Still, she warns that North Dakota farmers who remove windbreaks are setting up for increased erosion.
Outdated tillage methods also contribute to erosion. She cites an example of a farmer moldboard-plowing up and down the hills on his fields. That resulting water erosion tallied about 9 tons per acre.
It gets worse. That’s because the farmer had three times as much tillage erosion: 27 tons per acre per year of topsoil moved from the tops of the hills to the bottoms of the hills. The proof was in his wheat yields. He got 46 bushels per acre on top and 96 bushels per acre below.
“How do farmers and consultants manage that kind of variability?” DeJong-Hughes asks. “How do you manage 7.4 vs. 8.3 on pH? How do you manage that kind of organic matter differences with herbicides and P and K management?”
Saving soil is all about cover. While planting cover crops is one solution, DeJong-Hughes emphasizes smarter tillage.
“Reduced tillage has two powerful soil benefits. It leaves residue on the soil surface for cover, and it keeps the soil structure,” she says.
Tillage breaks up structure. The more aggressive the tillage, the more it breaks up the soil. That means reducing fall tillage. This leaves residue that holds the soil through the winter. Instead of conventional tilling, DeJong-Hughes recommends experimenting by renting a strip-tiller or vertical-till equipment, or leaving tillage until spring if soybeans will be planted.
Handy producers on limited budgets often make their own equipment by adding residue managers and berming disks to an anhydrous bar to lightly till the soil.
“Break tradition,” she says. “Think about what your soils need and pay attention to them.”
Vertical tillage is sometimes the only way to get into fields with wet, heavy soils. Other soils and regions require different approaches. Among the hilly fields in northeast Iowa, NRCS area resource conservationist Jered Finley regards tillage erosion in different terms.
“In Iowa, we don’t have an erosion problem; we have an infiltration problem,” he says. “Pore spaces (soil structure) are destroyed with tillage.”
Intense rains in recent springs have accentuated the problem. While some producers leave corn residue over winter, soil that’s tilled before planting is vulnerable to the 3 inches of rain per hour that have become more common. Even terraced fields have soil displacement.
Only established no-till fields (six years or more) hold up. That’s because water infiltrates the soil rather than running off as it does on cultivated soils that have created impenetrable crusts. Money from programs such as EQIP and the Conservation Stewardship Program help reduce some risk farmers incur for trying new cultivation methods. The program has steadily grown in the past few years.
With consistent abnormally wet springs, more producers recognize the urgency to change tillage practices.
“We need to treat the problem instead of the symptom,” Finley says. That means reducing tillage to let water seep into soil, rather than erode soil.
DeJong-Hughes admits change isn’t easy. Changing tillage methods is more than just changing a piece of equipment, she notes. It’s a whole system that requires education about managing weeds and banding fertilizer, for example.
“Keeping your nutrients and keeping your soil – all of it hinges around tillage,” she says.
The upshot is don’t waste your resources or let them blow into the next state.
Make do with less
While many farmers are proud of their equipment quantity, Ed Hegland figures he has bragging rights on how few pieces of equipment he needs. The Appleton, Minnesota, farmer has switched to strip-till and no-till to grow corn and soybeans.
Like Jodi DeJong-Hughes, he noticed dirt in the ditches on his travels to commodity board meetings and to the Twin Cities. He also noticed climbing equipment and fuel costs in his farm accounts.
In 2006, he rented equipment and experimented with strip-tilling his cornfields. By 2008, he was all in – strip-tilling corn and no-tilling soybeans.
While wild winds from the 2013-2014 winter moved topsoil from neighbors’ conventionally farmed fields, the 12- to 18-inch-tall cornstalks and bean stubble in his fields held soil in place.
“Strip-till takes more management,” he admits, “and it’s a challenge during harvest.”
Time is limited before freeze-up, and he has to pay attention to proper fertilizer placement as he tills an 8-inch-wide strip in bean stubble in preparation for the following year’s corn crop.
Because he’s doing less tillage, he needs less equipment: a 285-hp. tractor, a self-propelled sprayer, a planter, a combine, and a strip-tiller. Last fall, Hegland upgraded to a 16-row Soil Warrior for strip-tilling to match his 16-row planter. It gives him versatility to engage just the coulters or the coulters with the shanks. It also has two hoppers for him to variable-rate two different fertilizers based on grid sampling recently completed on all his soybean acres.
“I know exactly what fertilizer is going where in my fields,” he notes. “It won’t go away in water or wind erosion.”
He estimates he’s cut back fertilizer use about 25%. Because of fewer trips across the field (strip-till in fall and spring, planting, and side- dressing), he saves an even higher percentage on fuel and compaction.
“In 2009, the compaction from the combine and grain cart was tremendous for everyone,” he recalls. “I could drive my combine on strip-till ground with standing water; they couldn’t do that on fields tilled 8 to 12 inches deep.”
With several years of reduced tillage, Hegland has seen organic matter improve. Ag product dealers comment on the good soil structure and the number of earthworms.
Hegland appreciates the economics, improved soil health, and good yields of using less tillage.
“I think the cost aspect is pretty evident,” he says. “I think the soil conservation aspect of it is very important. I have young kids, and I want them to have the opportunity to farm and have great soil. I’m proud to conserve soil and that I’m building organic matter and soil structure.”