Ferrie: In Dry Soils, Is It Better to Use Anhydrous and Strip-Till or a Zone Builder?
With the unseasonal warmth and dryness, Farm Journal Field Agronomist Ken Ferrie is getting questions from farmers wondering about spring strip-tilling or zone building. One question came in from southeast Minnesota. For background and perspective, the farmer says his soil CECs range from 22 to 26, which means he's farming heavy clay. He spreads some turkey litter in fields and has some compaction where the litter went down. The grower used his zone builder, which is on 30-inch spacings, and ran it from 16 to 17 inches deep. He got good lift and fracture without blowouts above ground and no smearing below ground. His question to Ferrie in this week’s Boots In The Field podcast is: “Am I drying out the soil early in what looks to be a dry year? Or, am I making the soil more fit so roots can go down as they should?”
Ken Ferrie’s Response:
“You may be choosing between the lesser of two evils. Based on my past experiences, I would recommend staying away from building zones with the knife in the spring. Too many times I've seen this lead to stand-establishment problems. If it doesn't rain, you could be out of water down to the depth that you tilled. Without some freezing and thawing action, spring strips can have air pockets that don't settle back down before planting. That can cause the seedbed to have a false bottom that seed can then drop into, especially if we're running a seed firmer. In that case, what we will find are late emergers and they're planted deeper than the planter setting.
“If we plant into the unsettled zone, and then we get rain causing the zone to settle, we often end up with corn down in a valley that may cause it to be planted too deep, giving us depth issues and stand issues. Spring strip-till issues are less in sandy or silt loam soils and worse in heavier clay soils. My recommendation for the Minnesota grower would be to only do the areas of compaction to be safe, so we don't fight a tough seedbed this spring. If those strips dry out before planting, I would try to plant between the strips even if the ground there is compacted.
“A couple of slow, larger rainfall events will settle the soil and lessen some of the issues. But I don't think I would count on that. Strip-tilling with anhydrous in the spring on clay soils has the same issues with air pockets and drying out the seedbed. The air pocket issue can be improved by refreshening the strips ahead of planting. Spring anhydrous strip-till also has the potential to burn later in the spring. I have seen February-applied anhydrous in strip-till ding corn in a dry year. The problem with anhydrous burn is that in some cases it can hurt germination. But it is more likely going to burn roots when they reach the core, if it doesn't calm down before the roots get there.
The Importance Of Water
“When anhydrous is applied to the soil, it'll swing your soil pH to near 14. That pH will kill everything in its path, from soil biology to live roots. When this happens, the plants are usually in that V4 to V6 range when they start to show the stress. At that point there's nothing you can do but ride it out or replant. What will it take to tame down this high pH core? It's water. Two to three inches of water will safen things a lot. You do have time on your side. We don't need that 3 inches before we plant but we do need it before the root system reaches the anhydrous core in your soil.
“The dryer it is or the higher the rate of anhydrous, the bigger the risk. We would like to see three weeks between anhydrous and planting to reduce the risk of burn, but we really need water. With today's auto steer, we can safely apply spring anhydrous and then turn around and plant between the gas strips the next day. Planting right on top of them is when the risk shows up. If you're using spring ammonia or spring strip-till and we don't get enough rain to settle or calm down the anhydrous core, you may want to plant between your strips.”
Listen to Ferrie's response here:
Read more here:
Iowa State Releases 2024 Custom Farming Rate Data
Farmer Asks How To Improve P and K On Rental Ground
Scientists say the New Frontier for Corn Research is Found in the Crop's Roots
Seed Technology and Evolving Farming Practices Win Against Drought's Grip
