By Dan Davidson, DTN Ph.D., agronomist
Editor's Note: Dan Davidson provides insight into what farmers might do this spring to deal with wet soil conditions. The information was provided specifically to AgProfessional so that readers can talk with customers about alternative field work that might be necessary this spring and to allow consultants and ag retailers to determine recommendations for fertilizer programs fitting into a farmer’s unusual spring workload.
Farmers across the Midwest might be in store for another delayed and potentially difficult planting season. The 2009 season went out in a hurry with a lot of activities left undone and perhaps with corn still standing in the field, or soil conditions in compacted or in rutted shape. And unfortunately for many farmers, inclement weather set in before growers had the opportunity to complete their fall tillage.
In addition to less than favorable conditions left by the 2009 harvest, including saturated soil conditions, winter weather provided heavy snow pack which poses a significant threat for flooding in the Midwest — particularly if precipitation this spring is even normal.
The primary concerns farmers are currently facing are how they should handle ruts, compacted soil and perhaps weed control — although I do not believe disease or insect pressure will be any greater than normal.
Ruts & Compaction
Mahdi Al-Kaisi, Extension soil management specialist at Iowa State University said that for many corn growers it got too late in the fall to work their fields. He added that farmers have to basically choose between alleviating compaction or filling and leveling ruts.
Al-Kaisi says to avoid deep tillage tools. "Subsoilers or chisels aren't effective in the spring. It smears the soil and does not fill and level soil ruts. A light tillage pass is more effective." He explained that before making a tillage pass to be creative in deciding which machine to use and how to run it to move sufficient soil to fill ruts.
And if you worry about a wet spring, Al-Kaisi said growers can make the rut-filling pass early when the soil is still partially frozen and firm which will reduce the risk of further compaction. But he emphasizes that regardless when you make the pass to limit it to one pass. While a second pass might make a nicer seedbed, it would create more compaction.
One farmer I spoke with who left compaction, ruts and wheel tracks in his fields last fall offers a few other options. One is to strip till early to lose and dry the soil and fill ruts. Then make a second pass to apply fertilizer and freshen the strip just prior to planting. For those that don't strip, another option is the run the planter empty once to open the soil and then run the planter a second time with seed.
And if you are not a strip-tiller he suggests using a field cultivator or soil finisher to fill ruts and loosen the soil underneath tire lug marks. And for corn after corn producers he suggests using a vertical tillage tool because it will process residue, fill ruts and fracture the soil underneath tire lug marks.
Tillage & Residue Management
DeJong-Hughes, regional Extension educator with tillage responsibilities for the University of Minnesota, is concerned about the big matt of corn residue that is still lying, untouched on many fields in Minnesota. "For growers going to soybeans it will be easier to plant with the residue because planting is delayed a few weeks."
For growers going back to corn they will need to prep the field and manage the residue. DeJong-Hughes explained that if the soil is drier and in tillable conditions to disk 2 to 3 inches deep. But if the soil is wet, don't disk. Instead use narrow point without wings on cultivators and go no deeper than 4 inches.
"Stay away from rippers and plows this spring," said DeJong-Hughes. "There is a risk of smearing and it will affect the crop." She said for growers who decide to plow this spring they are taking a big risk. "The residue will be incorporated (8 inches) into a wet soil and won't decompose at that depth in wet year."
After a late harvest, many farmers want to know if they can still control winter annual weeds the following spring. With less use of residual herbicides and tillage, winter annuals have made a comeback. And unless farmers applied a burndown and residual last fall they can expect to see some of these weeds during the spring.
Winter annual weeds include purple deadnettle, henbit, chickweed, horseweed (marestail), pennycress and a number of mustard species.
While spring application works on winter annual weeds, expect control to be more variable due to larger weed size and cool weather conditions that impede herbicidal activity.
To choose the right herbicide program, farmers should take an inventory of what weeds are present. The most common herbicides used are 2,4-D and glyphosate either alone or in a tank mix. Fortunately, 1 pint to 1 quart of 2,4-D or 0.5 to 1 pint of 2,4-D plus 1 quart of glyphosate (or equivalent) effectively knocks off winter annuals in the spring if done when small. Farmers should not wait until late in the spring after the weeds bolt because they cannot be controlled effectively. A residual herbicides with early-spring burn-down will provide a weed-free seedbed at planting. This eliminates the need for applying herbicides at planting.
Dan Davidson, DTN Ph.D. agronomist, writes articles on agronomy and crop production for growers across the Corn Belt and dispenses timely advice on production practices and decisions. He can be reached at Daniel.Davidson@telventdtn.com. For more information visit www.dtnprogressivefarmer.com.