There are two main goals with fall tillage: size and incorporate crop residue to begin the breakdown process; and mitigate any soil compaction that you’ve caused during field operations through the course of the growing season. How you accomplish this, however, gets a little more complicated. In this interview, Iowa farmer Jeremy Swanson sizes up the various tillage implements, from the moldboard plow to high-speed vertical till machines, and provides his review of each. 

Best as a Lawn Ornament: The Plow

The plow is the earliest tillage tool out there. It’s designed to flip the entire soil profile over as a way of burying residue and getting black dirt on top. That worked for many years, and we could go into all the biological reasons that worked for a time. (We mention some of those reasons below.) But the plow can lead to serious environmental and erosion issues like we saw during the Dust Bowl. 

From FCLG: The moldboard plow, in its simplest form, traces its origins back to the time before Christ. Modern versions originated around 500 years ago. By 1814 Thomas Jefferson had crafted a plow out of cast iron. In 1837, John Deere invented the modern steel moldboard plow, which replaced the common cast iron versions. By 1875, his Moline Plow Works factory was cranking out seventy-five thousand plows a year. While the moldboard plow was adept at quickly transforming prairie and other landscapes into arable land, it is also efficient at destroying healthy soil structure, which lead to erosion, runoff, and other issues.

I think the best use for a plow is to use it as a yard ornament. Put it out at the end of your driveway with some rocks around it—and maybe a flagpole sticking up through the middle. Yes, there are still some use cases for it: A plow works well around field edges to cut back fence rows. Or to make a grass waterway or bring CRP land into production. But as far as it being a primary tillage piece on your farm, it's not a choice I'd recommend.

Plow: Short-Term Gain with Long-Term Trouble

When you plow: You introduce a bunch of oxygen into the soil profile. The soil biology goes nuts. And they start feeding and growing and repopulating. In turn, these organisms cycle all that nutrient load from the residue, whether that’s crop or native prairie, much quicker. You get a load of phosphorus, potassium, and nitrogen freed up and available—a real buffet of nutrients for that next crop. Those aren’t salt-based nutrients; they’re natural nutrition for the plants. From a nutrient cycling standpoint, the plow works very well. Short term, the plow is awesome. Long term, not so great. 

The Best to Preserve Soil Structure: Disc Ripper or Vertical Tiller

After a while, farmers figured out that aggressive tillage wasn’t the best thing in the world. And that’s when implements such as the disc harrow and V ripper entered the scene. Discs do a nice job of sizing the residue and throwing a little bit of dirt to incorporate some of the crop residue. Discs have changed over time as companies play around with disc types, whether that’s making them more or less concave or playing around with different edges, whether that’s a straight edge, notched, or rippled. 

From FCLG: Opinions and claims made by sales literature on disc designs for these implements vary greatly. Some people hold that smooth edge discs are ideal in normal soil conditions and can be beneficial for soil leveling. Discs with scalloped or textured edges can size up especially heavy residue. As Jeremy stated during his interview, discs also vary in their concavity. Manufacturers also play around with disc diameter and material (ex. carbon steel vs. boron steel). Aside from disc shape and size, disc harrows are generally split into two categories—single-action and double-action. Most modern discs found on corn ground are double-action discs, with two or more disc gangs arranged in a X pattern for heavy residue processing. 

A Disc Dilemma

One problem with a disc, in my opinion, is that it can actually create soil compaction. Think about it: When you’re driving down the interstate and you see the construction company building a new road, what tillage tool do you see them using? A disc. It’s one of the implements they will use to make a good, firm base to build a road on. 

Alternatives to the Disc

There are several alternatives in the market to the disc, such as the V ripper or deep inline ripper. They are able to reach down deep into the soil profile to break up soil compaction. The straight tips fracture the soil but don’t throw a lot of dirt. Then companies started designing different wing-type tips, which are able to throw more dirt up top to help cover residue and fracture more of the soil profile. 

Somewhere in there, the disc ripper came along. We figured that if we could put disc blades ahead of one or more gangs of shanks, we could size the residue, break up compaction, and throw some dirt on top of the residue at the same time. 

And more recently we’ve seen vertical tillage come into play. Vertical tillage is much faster than a ripper or traditional disc. And guys like to go fast. Salford was one of the pioneers with these implements, and the industry has taken off from there. 

Level the Planting Field: The Correct Depth for Tillage

With a disc ripper, I’d make your depth at least half the distance between your shanks. So, if your ripper is running thirty inches between shanks, you’d need to be at least 15 inches deep in the soil to get full fracture of the soil and so that it’s not throwing a ton of dirt. With a vertical tiller, there’s not much depth there; maybe between one and five inches, and some of this may depend on how fast you pull the implement across your fields. 

The biggest consideration with setting the depth on a vertical till implement is getting it deep enough to level your fields. After all, you want your ground as level as possible in preparation for that planting pass. I’ve seen farmers run vertical tillage implements in spring as well, because, when set correctly, they can do a nice job of leveling the soil.

The Best Overall Tillage Strategy: Till Only When You Need To

Overall, I think we need to be moving away from tillage. Only use tillage when you need to—when conditions call for it. Why? With the current fuel prices, limited access to labor, and the investment cost of the tillage implement (and possibly needing to buy another tractor), I just don’t see how there’s a return on that investment. Hence the reason I transitioned away from conventional tillage and now do strip-till and no-till on my farm. 

From FCLG: Jeremy has both strip till and no till acres on his farm. Look for a future article series with Jeremy where we’ll dig into his story of transitioning from conventional tillage to strip and no till. We also asked Jeremy what his thoughts were on farmers running more than one style of tillage implement. Here was his response:

Looking Ahead to Residue Management

In our first article in this series, Jeremy listed residue management as the top reason for performing fall tillage. In our next article, we’ll break down residue management further and look to our natural landscapes, such as our forests and prairies, for inspiration.