There is a ton of advice out there on tillage. Just look at the variety of tillage implements on the market today. Or ask a fellow farmer about his or her ideal setup.  But your end goal for your fall tillage pass is really quite simple. The Fellowship of Christ Like Growers recently sat down with Iowa farmer Jeremy Swanson to talk all things tillage, and this is where we begin our interview.

Your Ultimate Tillage Goal: Create a Perfect Seedbed

I think there's a lot of guys that probably don't even think anymore as to why they make the tillage pass. It's just become one of those things they've always done. But with that being said, I think there are probably two things that come to mind right away for most guys. Number one would be residue management—sizing that corn stalk residue and getting it worked into the ground. 

When you’re planting your crop, you want good seed-to-soil contact, so we need to manage our tillage with this end goal in mind. We’ve learned over the years that if we go in and do tillage in the fall and try to size and bury some of that residue, as much of it as we can, we’re left with black dirt that’s good for planting and achieving that optimum seed to soil contact. 

Tillage Goal: Eliminate Soil Compaction

The other primary reason for fall tillage is soil compaction. We need to break up the compaction that we caused during the growing season. Every trip we make across the field with equipment packs the ground. Even rain contributes to soil compaction. We both want and need rain, but from a compaction standpoint, rain packs the ground. To alleviate this compaction, we till our ground to get the soil opened up and introduce oxygen back into it, and loosen the soil structure. So, when we go to plant next year, the plant's roots are able to go down into the soil profile rather than hitting a hard layer that they can’t get through. 

Does Tillage Provide Weed Control?

Residue management and compaction mitigation are the two big reasons for doing tillage in fall. In my opinion, anything beyond that becomes recreational tillage. Weed management is a concern also, but fairly secondary to our other reasons for making that fall tillage pass. If you don’t do tillage, there’s a certain weed bank that will start to grow in the fall that would suck up moisture and nutrients.

So, with your fall tillage pass you’re going to bury some of that weed seed. But then you’re also pulling up other weed seed, which can be a problem going into the following growing season. That’s why I consider weed management to be far secondary to residue management and compaction mitigation: tillage just changes the weed management game rather than fixing anything, at least from what I’ve seen. 

Tillage Goal: Make Nutrients Plant Available

By chopping your residue up and getting it buried, you’re placing it in the soil profile near the bacterial and fungal communities that feed on the carbon residue. By incorporating this residue into your soil in fall, these organisms can go to work on it, chew it up, process the nutrients that are stored within it, and then release it back into the soil profile for growing next year’s crop. 

However, it’s important to remember that the aerobic organisms in the soil do the majority of the primary breakdown of that residue. The bacteria, fungi, and other organisms require oxygen, which you’re mostly going to have in the top (probably) six inches of the soil. If you till down eight, ten, or even fifteen inches deep, you’re bringing up anaerobic bacteria that aren’t going to break down the residue as quickly. Plus, you’re burying the aerobic bacteria deeper in the soil, which is going to spell trouble. In Iowa, where I farm, our soils are so forgiving; we have such rich, black dirt with deep levels of organic matter. Here, we can get away with that; the residue still disappears. However, I don't believe we get the nutrient value back as quickly as we would if we allowed those aerobic bugs in the top six inches of the soil to properly digest the residue and keep the nutrient cycle working. 

Looking Ahead to Spring

As Jeremy described in our interview, your end goal for fall tillage is to set yourself up for ideal growing conditions in spring—a perfect seedbed. This means sizing and incorporating crop residue (especially important for corn growers), and breaking up any soil compaction that field operations have caused over the course of the growing season. In our next article with Jeremy, we take a look at the many tillage implements working the land and what they each bring to (or take from) your operation.