With soil moisture at or above field capacity, it won’t take much spring rain to make fields too wet for good planting. The challenge is to avoid creating compaction. It’s tough to stay out of fields and not work soil until it’s ready this spring, especially when you weren’t able to get tillage done last fall.
Spring isn’t the time to try to alleviate compaction with tillage, says Iowa State University Extension agronomist Mahdi Al-Kaisi. You’ll likely just create more. It’s important to assess fields and avoid doing more tillage than necessary. Even light tillage with a disk or field cultivator can make a not-so-good situation worse.
No-till and strip-till systems also can run into problems if soil is too wet. They can create sidewall smearing and compaction in the seed zone, restricting root growth and hurting yield. “No matter what system you use, pay attention to your soils. If they’re not ready, stay out of the field,” advises Dave Nelson, owner of Brokaw Supply at Fort Dodge.
• Wet fields are increasing soil compaction potential.
• This is a year to try doing less tillage than normal.
• Even in no-till, be sure soil is dry enough before planting.
He knows from experience; his family farms, and he and his staff help customers set up and adjust equipment. He sees the problems when farmers work wet soil and plant before fields are dry enough. Waiting a few days can make a tremendous difference in soil condition.
It’s best to strip till in the fall, not the spring. But if you couldn’t get the job done last fall, do it in the spring. “Spring strip till requires good judgment, just like field cultivator tillage does in spring,” says Nelson. “You make a seedbed with the strip-till machine prior to planting. If you strip till when a field is too wet, you smear the sidewalls of the planting zone and bring up clumps. Extra care must be taken. Be sure soil conditions are ready before you enter the field.”
Sometimes farmers use a field cultivator to dry out soil so they can plant a few days earlier. Problem is, that usually creates compaction. A field cultivator sweep can smear soil that’s too wet.
If a sweep runs 4 inches deep in wet soil, for example, it’s working the top 4 inches but is smearing at the bottom of the sweep, compacting a layer of soil. It’s disconnecting the top 4 inches of soil from the layer below the sweep, so when crop seedling roots grow, they run into the smeared layer and can’t penetrate.
Usually with spring strip tilling, you’ll need to use a different type of knife to inject fertilizer. “In the fall we use a mole knife,” says Nelson. “It has a bigger foot on the bottom of it. In spring we use a slim knife, similar to an anhydrous knife.”
Get good seed placement
For spring strip till, Nelson advises using a rolling basket behind each row unit on the strip-till machine. That attachment helps pulverize soil on top of the berm you create. When you come back to plant into the strip, the planter row unit doesn’t jump so much, and it delivers consistent seed placement. When the row unit is jumping, you don’t get very good seed placement.
Be careful if you apply anhydrous with your strip-till rig in spring. You may not want to apply the full rate of N if there is potential for root burn of the corn seedling. “You can split the rate,” says Nelson. “Apply part of it at planting and sidedress the balance later. Consult your agronomist to make sure you won’t be burning corn roots by putting too much N on at planting.”
This is a year to consider trying no-till or strip till. Not only can these systems save time and expense, but both also are eligible for cost share from the USDA Environmental Quality Incentives Program and Conservation Security Program.
READY TO GO: Even strip-till and no-till systems can run into compaction problems if used when soil is too wet. Though studies have documented the benefit of early planting, agronomists emphasize it is more important that the soil be ready.
This article published in the April, 2010 edition of WALLACES FARMER.
All rights reserved. Copyright Farm Progress Cos. 2010.