All Roughed Up

ST. LOUIS (DTN) -- A clear loser has emerged in this damp, delayed harvest -- rutted, roughed-up fields. As the harvest clock ticks, persistent wet conditions have forced farmers to venture into fields under less-than-ideal conditions in some parts of the Midwest.

Beating up your fields is bad for both morale and soil health, but sometimes unavoidable, noted corn and soybean farmer Pete Pistorius. "Ruts are just everywhere this year; everyone has been so wet," he said of the central Illinois region where he farms. "It will take a couple years to repair the damage we've done there."

The sight of deep ruts and freshly mashed fields might send you running for your plow, but experts urge caution and patience. It's best to wait until fields are as dry as possible before trying to smooth out ruts with tillage, and you should aim for a light touch when you do, University of Minnesota Extension Crops Educator Jodi DeJong-Hughes told DTN.

"Their first instinct is going to be to try and dig deep and go under the rut and really tear it out of there, and that's probably more detrimental than they think," DeJong-Hughes said. "The structure in the soil acts like mini columns to help hold up the weight of equipment, so the more you till that up and deeper you till apart that structure, the more compaction you can have later."

ASSESS AND ACT

Ruts or tracks shallower than three inches might actually not require any reparative tillage, added Iowa State University Extension agricultural engineer Mark Hanna. "Sometimes, the winter freeze-thaw cycle will do as much to break up compaction," he said.

However, larger ruts will require tillage repairs, even for no-tillers who may cringe at the sight of a plow, DeJong-Hughes warned. "I'm very much for reduced tillage, but those ruts have to be taken care of," she explained. "It's like falling off a diet on the weekend -- you did do a little damage but it's something that you can recover from."

To fill in ruts, DeJong-Hughes recommends leaving disk rippers or moldboard plows in the shed. Instead, consider a lighter pass with a chisel plow or even a field cultivator -- just enough to break up the sides of the ruts and level the field for planting next spring.

Try to test soil moisture with a spade before you enter any damaged fields, Hanna said. Also, keep in mind that just as the field might be drying out enough to hold equipment, the risk of compaction is peaking, DeJong-Hughes added.

"About three days after a really good rain, right when they can get back out into the field with equipment -- that is the best time to compact soil," she noted. "It's nature's cruel joke."

Flee the field at the first sign that your repair trip might be doing more damage, she added. "If the soil is smearing and clumping up on the back of the implement -- get out of there," she said.

For farmers who run out of time in the fall to till, spring repair is also an option, but avoiding wet soils will again be critical, Hanna warned.

To protect soil structure during spring rut repairs, DeJong-Hughes recommended that farmers steer clear of tillage equipment with shanks or disks. Instead, consider using a coulter cart or vertical tillage tools, especially for shallow ruts.

LIGHTEN A HEAVY LOAD

A modern combine can weigh around 20 tons per axle, and a fully loaded, 1,200-bushel grain cart can break into the 40-ton-or-more-per-axle range, DeJong-Hughes pointed out.

That's a lot of weight for wet soils, but farmers can take some steps to lighten the load. Pistorius purchased a second grain cart so he could keep the combine's grain tank lighter and run half-loads across the field to waiting trucks. About 80% of compaction happens on the first pass, so Hanna and DeJong-Hughes also recommended limiting field traffic to one area and detouring to make sure the grain carts follow in the combine's tracks.

In particularly wet areas, growers might have to weigh the value of grain quality with soil health and perhaps wait for the ground to freeze, Hanna added.

In central Iowa, Pete Bardole is doing just that on his no-till corn and soybean operation in Greene County. Thirty soggy soybean acres and hundreds of corn acres remain, but Bardole is parking the combine for now. "The soil is our livelihood -- we try to be really careful," he told DTN. "Next week is supposed to get really cold, and if the ground freezes enough, we'll probably go in and try to get them then."

BRACE FOR THE DAMAGE

Regardless of any rut repair you might attempt, you can expect the underlying soil compaction to leave its mark for a few years, both DeJong-Hughes and Pistorius noted.

Pistorius plans to supplement his first rut-fixing tillage pass with some deeper ripping passes once fields are much drier, but said next year's crops will suffer regardless. "Initially, you'll see discoloration and your corn will be stunted," he predicted. "The next place you'll see it is on the yield monitor."

A study DeJong-Hughes conducted five years ago confirmed these predictions.

The fall of 2009 was a particularly muddy one -- "Do ruts count as tillage?" DeJong-Hughes recalled one despairing farmer asking. Using GPS, DeJong-Hughes marked out the rutted areas in some fields and then revisited them the next spring and summer. The results were clear: Even though the ruts had been filled in, corn and soybean plants that grew there were shorter, yielded around 15% less, and matured more slowly than their un-compacted neighbors. (Interestingly, plant populations were unaffected, she noted).

Overall, the compacted soil structure will warm more slowly, hold less water, and limit root growth, DeJong-Hughes said. "They're going to see a yield drop for two to three years," she concluded.

To read more about repairing ruts and avoiding compaction in wet conditions, see this University of Minnesota publication on fall tillage: http://goo.gl/….

Emily Unglesbee can be reached at emily.unglesbee@dtn.com

Follow Emily Unglesbee on Twitter @Emily_Unglesbee.

(PS/AG)

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