Tillage Tips

Vertical-tillage is a good tool for farmers who want to till, yet still preserve residue. Like all tools, though, it has limitations.

"In 2011, we dealt with a flood, and there were southwestern Manitoba areas that were typically no-till," says Marla Riekman, a soil management specialist with Manitoba Agriculture's ag resource branch who spoke at this week's virtual Soil Management Summit (SMS). "People were in a panic about how they were going to deal with (plant into) all this residue and wet soils and they didn't know what to do. So, they started trying vertical-tillage."

It worked. Really well.

"People would say, 'You know, I can run it through water,'" she says. "Well, just because you can do it doesn't mean it's a good idea."

In one case, an equipment dealer demonstrated how to vertically till heavy and excessively wet soils.

"The person who ran the farm said, 'I'm glad I don't have to take this home and clean it up because it was an absolute mess," says Riekman. "It clodded up the soil, leaving these hard clods all over the surface."

The lesson?

"Everything has a limitation," she says. "Make sure that you work within that limitation."

Choices

That anecdote fits the plethora of choices that exists for farmers when deciding to no-till, till, or pursue hybrid choices like strip-till. Riekman and Jodi DeJong-Hughes, a University of Minnesota Extension educator, gave these tips at the SMS.

• All tillage — even no-till — moves some soil to clear a seed path. High-disturbance openers, such as hoes and sweeps and injection units, key tillage that leaves at least 50% of the soil surface exposed to subsequent wind and water erosion, says David Lobb, a University of Manitoba soil scientist.

Still, some tillage strategies move a lot more soil than others do.

"The more tillage you do, the more it can impact things," says DeJong-Hughes. "Soil that is not well aggregated can break apart and blow away very easily. So, the more tillage you do, the easier the soil is to move."

• Not surprisingly, moldboard plowing does a number on soil structure. "On flat, heavy soils in western and southwestern Minnesota, it is still used," says DeJong-Hughes. "What it does is totally invert the soil."

This shatters soil structure and leaves soils prone to erosion, she says, leaving only 10% to 15% residue on top. Moldboard plowing also fuels loss of soil carbon that escapes into the atmosphere. This lost carbon deprives the soil of a way to build organic matter that benefits soil in myriad ways, from boosting water infiltration to better using nutrients.

• Implements that till at a shallow depth don't always preserve soil. "If you use a speed disk, you can go really fast because you aren't going as deep," she says. Another plus is because less soil is turned over, carbon is preserved.

The minus is that the soil is being thrown further, which can shatter structure and spur erosion.

• Strip-till can form a marriage of sorts between tillage and no-till. Coulters and shanks are two tillage tools used on strip-till rigs. "What's great about both is they are only disturbing about a third of the soil," she says. "Even if strip-till coulters or shanks are set aggressively, they only go over a third of the field," she says.
• A chisel plow can travel quickly across a field, but it can leave scant surface residue. "What we found in tillage research that we do with farmers in their fields with their equipment is it can leave anywhere from 20% residue to 40% residue," she says. "What that's based upon is how the chisel plow is set. If a chisel plow is set fairly aggressively, you can change out the points to ones that turn over less soil and leave more residue and leave more soil structure intact. If you don't have money for a brand-new piece of equipment right now, changing points is a way you can preserve soil structure without a lot of cost."
  
• Save big discs for road construction. "Big discs are really not one of my favorite things out there," says DeJong-Hughes. These units — which can till the soil 10 to 15 inches deep — negatively impact the soil surface, she says. "They're really good at building roads," she says. Not so for farming. One of the negative factors about them is they destroy air pockets that help build structure and allows roots to grow, she says.
• Proper drainage is crucial for crop production, particularly when planning to no-till heavy soils. If tile drainage isn't an option or cost is a concern, though, a cover crop or a long-rooted cash crop like alfalfa may do the heavy lifting to get a field ready for no-till.

No-tilling has worked on a field south of Winnipeg with heavy clay soils for nearly 20 years, Riekman says.

"The reason it has been successful is that the farm manager went in with a plan that he wanted to no-till," says Rickman. "He actually sprayed out an area of alfalfa that had been in there for three or four years and direct seeded into it. He used alfalfa as a transition crop to move into a no-till system because the alfalfa created the internal drainage that allowed the water to move down. His soil actually adapted very easily to no-till."

• Let those droughty dog days of summer break up compaction. They are good for something, because the soil cracking they fuel can shatter soil compaction.

"When you see those soils crack in the summertime, you are doing deep-tillage without having a ripper go through," says DeJong-Hughes. In some cases, cracks up to 4 feet deep can occur in those soils during those summertime days — something that would be impossible to do via deep tillage.

• Control erosion control first before testing for soil health. "If you see erosion in a field, you don't need a soil biology test," says DeJong-Hughes. "You need to fix the erosion."