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 soil compaction this spring. Granted, it's tough to stay out of fields and not work soil until its ready, especially when you weren't able to get tillage done last fall and time is tight this spring.
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 compaction. "It's important to assess your fields and avoid doing more tillage than necessary," he says. "Even light tillage with a disk or field cultivator can make a not-so-good situation worse."
Al-Kaisi has three key points for farmers to keep in mind this spring:
1) Wet fields are a challenge, increasing the potential to create soil compaction.
2) This is a year for farmers to try doing less tillage than would normally be done.
3) Even in no-till and strip-till systems, be sure the soil is dry enough before getting into the field.
Better off waiting until soil conditions are favorable before planting
No-till and strip-till systems can also have problems with 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.
Brokaw Supply and its employees spend many hours helping customers set up and adjust the equipment they sell. The last two springs have been wet, and Nelson has seen compaction related problems due to farmers working soils too wet and planting before soils are dry enough. "Waiting a few days can make a tremendous difference in soil condition," he notes. "We've seen most times, that by waiting a couple days it actually gives us more yield due to the more favorable planting conditions."
READY TO GO: Even strip-till and no-till systems can run into compaction problems if used when soil is too wet. Though researchers have documented the benefits of early planting, agronomists emphasize it is more important that the soil is ready.
If possible, it's easier to strip till in the fall, not spring. But if you couldn't get the job done last fall, you have to do it this spring. "Spring strip till is similar to field cultivator tillage 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 get into a field: you have to be patient."
Give roots a chance to grow into mellow soil, that's not compacted
Sometimes farmers use a field cultivator to dry out soil so they can plant a few days earlier. Problem is, that usually creates compaction and smears the soil about 4 inches deep where the sweep ran. "A field cultivator can be your worst enemy, setting yourself up for problems right from the start," he adds.
If the sweep runs 4 inches deep in wet soil it's working the top 4 inches but is smearing at the bottom of the sweep, compacting a layer of soil. You're disconnecting the top 4 inches of soil from the layer below the sweep and when seedling roots of the young crop grow down, they run into the smeared layer and can't penetrate.
Usually with strip till in spring, 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 the spring we use a slim knife, similar to an anhydrous knife."
What changes should you make if you're doing strip till in spring?
For spring strip till, use a rolling basket behind each row unit on the strip-till machine, he advises. 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 and it delivers consistent seed placement. When the row unit is jumping you don't get very good seed placement.
Be careful if you put anhydrous on with your strip-till rig in spring; maybe not apply the full rate of N as 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 the year to try no-till or strip till or at least check into it. Not only can these systems save time and expense, no-till and strip till are eligible for cost share from USDA's EQIP and Conservation Security Programs.