Avoid desire to plant too wet

Yet again a large share of farmers in the Midwest face a wetter-than-usual spring. And after at least two wet springs, there is fear that this season could present another muddy mess to plant through.

Even if instincts are inspiring you to push the throttle ahead, remember that the faster you drive while planting, the more down pressure you need to keep the row unit on the ground, observes Dennis Bollig. And higher down pressure settings can increase soil compaction.

True, today's high-tech sprayers "can control down pressure better, so they're trying not to exert any more than what is needed to get the seed in the ground at the proper depth," Bollig adds.

But that technology has its limits, and boosting field compaction has a direct impact on yields, adds the Fenton, Iowa, farmer as well as president of Dragotec USA. "Soil compaction can absolutely blow up in a wet spring. Even with a good tillage program, your tractor is causing compaction, and a field cultivator is not going to overcome that," says Bollig. "Compaction can cause a lot of variability within a field and ultimately lead to a challenging harvest."

A survey of 700 corn farmers conducted by Dragotec USA shows more than 48% say delayed planting is their biggest concern among all yield-limiting factors affecting their crops.

Sidewall Compaction Biggest Threat To Yields

Besides causing deep soil compaction, planting in wet conditions leads to micro-compaction of furrow sidewalls.

Sidewall compaction suppresses yields by itself. But the yield-killing potential of sidewall compaction is accentuated when weather conditions turn dry after planting, observes Paul Jasa with the University of Nebraska.

An example of what can happen as a result of sidewall compaction can be seen in the image above. Note the roots that were forced to grow sideways as a result of a smeared sidewall and related soil compaction.

Jasa has spent his professional lifetime researching planting issues and planter operation.

How To Determine If It's Too Wet To Plant

Based on his research and considerable experience working with farmers, Jasa offers the following methods to determine if fields are too wet to plant.

• Collect a handful of soil from your desired planting depth and squeeze the soil in your fist. If moisture and soil cling to your palm, the soil is too wet.
• Take a similar soil sample and form it into a ball and drop it to the ground from about waist high. If the ball remains mostly intact or breaks into only a few pieces, the soil is too wet.
• Observe your planter in the field. If soil is building up on the rubber closing wheels, the soil is too wet to plant. You should inspect the seed furrow periodically for signs of soil smearing and sidewall compaction.
• Check for sidewall compaction. Do this by digging across the seed furrow looking for unbroken, V-shape walls left by the opener.
• Check to make sure that the seed furrow is closed using minimal down pressure on the closing wheels. Angled closing wheels are designed to perform best when planting at a depth of 2 inches. The risk of the seed furrow not being closed or opening up increases with shallower planting depths.

How To Avoid Sidewall Compaction

Jasa also offers the following tips to avoid sidewall compaction:

• Reduce the down pressure on both the gauge wheels and the closing wheels. This is one of the most important adjustments you can make to avoid sidewall compaction.
• Try to leave some crop residue over the row to delay soil drying and reduce crusting.
• Level the planter from front to rear or possibly operate it slightly tail down to improve seed-to-soil contact and seed furrow closing. The closing wheel arm must be level for angled closing wheels to function properly.
• Use seed firmers to improve seed-to-soil contact when using two spiked closing wheels per row to break up sidewall compaction.
• Consider employing various types of spiked closing wheels. In general, closing wheels with long straight tines are more aggressive than those having short or curved tines. The aggressive closing wheels tend to dry the soil and may require a seed firmer to improve seed-to-soil contact and a drag chain to level the soil.
• Consider adding just one spiked closing wheel per row. This will break up the sidewall compaction on one side of the furrow and close the seed furrow more effectively in a wide range of conditions.
• Stagger closing wheels to reduce the potential for the seed furrow to open up as the soil dries. If using one spiked wheel and one standard rubber wheel, place the spiked wheel in front.