Act on Compaction

December 17, 2011 12:45 AM
Act on Compaction

Tips to help reduce yield losses from implement traffic

In order to till, plant and harvest, you have to drive over a field. The irony is that soil compaction leads to yield losses of as much as 10%, according to research by Iowa State University Extension ag engineers.

Yet, such losses don’t have to be inevitable. You can minimize the potential impact of soil compaction on yields by managing equipment, specifically tires, more effectively. Consider the following tips to help prevent soil compaction issues in 2012.

Use the right tires. Although bias tires are often the cost-conscious choice, radials are able to carry more weight at lower inflation pressures, according to Scott Sloan, product manager for Titan International.

Lower pressures often provide better flotation and cause less compaction. The size and shape of a tire can affect flotation and load capacity. In some parts of the U.S., Sloan says, the tendency is to use taller and narrower tires that offer a longer footprint (one to two additional lugs), resulting in increased traction. The larger tire chamber also means the tire will carry the same load with less air pressure.

Tall, narrow tires are often used in dual and triple setups, which further improves flotation and load capacity. With extra tires on the ground, the weight is distributed over more area, which leads to less compaction in the tracks. However, with more tires, there are more tracks, which isn’t always a good thing, Sloan adds.

"Studies show that 70% to 90% of subsoil layer compaction occurs on the first pass," he says. "It’s important to limit wheel traffic as much as possible. Having duals or triples creates extra tracks and extra areas of compaction."

Reduce trips. Traffic is the main cause of soil compaction. Combine two implements in the same pass or use wider equipment if power is adequate, says Mark Hanna, an Iowa State University Extension ag engineer. "Control traffic so you drive on the same areas repeatedly, which will help minimize the opportunity for compaction issues in the rest of the field," he says. "Reducing the number of tillage passes can also help preserve soil structure and increase organic matter."

Use a smaller tractor. Lighter tractor axle weights lessen the likelihood of soil compaction. Planting, rotary hoeing and cultivating require less horsepower. If a choice in tractor size exists, go with the smaller one.

Don’t work wet fields. This is easier said than done, Hanna acknowledges. "If conditions are too wet in the spring, producers could smear the seed furrow sidewall, a form of soil compaction that makes it difficult for root systems to move laterally," he says. "Check the planter’s press wheels and keep the pressure slight by lightening the tension on the downspring mechanism."

Checking soil moisture takes just a few minutes. Probing the top 1' to 2' with a hand soil probe to assess a field’s soil moisture condition is time well spent, Hanna says. Or check soil moisture by pushing a ribbon of soil between your thumb and index finger. If it breaks off within an inch or two, the potential for creating compaction is less. However, if the ribbon stretches out to 4" or 5", the soil is still too wet. A third method is to make a ball of soil 2" in diameter and toss it into the air. If it hangs together until it lands, it has a lot of cohesiveness and is probably too wet to work.

If you have soils that are perpetually wet, consider tiling those fields. Since wet soil is more susceptible to compaction than dry soil, it makes sense to eliminate wet spots if possible. An added bonus is that dry soils tend to warm faster in the spring.

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