PowerManager "Powermanager Tips"

A TJ tractor owner asks...

I’m concerned about the effects soil compaction will have on my crop yields. How do tractors with tracks and tires really compare?

Many producers are concerned about soil compaction because of the serious effect it can have on present and future crop yields.

Soil compaction in itself is not necessarily a bad thing. Just look at planters where “packer wheels” insure good soil to seed contact for consistent germination. The problems with soil compaction arise when wheel traffic from tractors and equipment firms soil beyond what is considered optimum for favorable germination and root development. Overly compacted soil results in restricted root growth, poor root zone aeration and poor drainage.

Because of the use of tractors and equipment in crop production, some soil compaction is inevitable, but you can minimize the damage with use of the proper tires and good soil management practices.

Tires vs. single tracks

Ag researchers at The Ohio State University studied the effects of track and wheel-type 4WD tractors on soil compaction.¹ They tested two 4WD tractors with dual radial tires, one with properly inflated tires, and another with over inflated tires. And, they tested two Cat Challenger tractors with rubber tracks. Researchers at North Dakota State University performed a similar test.² Here’s what they discovered: the tractor with properly inflated dual radial tires ranked as the best. The tractor with over inflated dual tires ranked worst, while the performance of the rubber tracked tractors tested fell in between.

Here’s why: When an implement is being pulled, the weight transfers from the front axle to the rear axle. On a tractor with tires, this reduces the load on the front tires and only slightly increases the pressure under the rear tires because the tires “spread out” to distribute the additional weight. Radial tires increase footprint within increased loads. They have the ability to maintain virtually the same ground pressure with different loads.

Ground contact pressure is directly related to tire pressure. An over inflated tire has a smaller footprint, greater contact pressure and thus greater soil compaction.

On a tracked tractor, weight transfers in the same way except that the track does not have the ability to “spread out” to distribute the additional weight. The result is a significant increase in ground
pressure under the rear wheel.

Tires vs. Single Tracks

The blue line shows the ground pressure for tractors with and without implements, and with different tire and track configurations. The higher the “peak”, the higher the ground pressure.

REFERENCES

¹ Abu-Hamdeh, Nidal H., Soil Physical Responses to Tractive Devices for Two Soils in Ohio.The Ohio State University, 1995.

² Solseng, Elton, Relative Soil Compaction Effects by 4-Wheel Drive and Rubber Tracked Tractors, The North Dakota State University, 1995

Good management practices can prevent soil compaction

• Reduce the inflation pressures of tires to the manufacturer’s minimum suggested levels for the load. This increases the contact area of the tire to the ground and spreads the load over a greater area. It doesn’t cost much—just the price of a tire pressure gauge—but the savings over the long haul can be significant. (And, fuel consumption will be less, too!)

• Tractor wheel slippage is a big contributor to shallow soil compaction. Mechanical front-wheel-drive tractors and four-wheel- drive tractors can pull heavier loads at lower levels of wheel slippage than two-wheel- drive tractors. This lower amount of slippage will help reduce levels of soil compaction.

• Ballast your tractor properly and remove any unnecessary weight – fluid from tires, wheel weights etc. Always ballast with iron, not liquid. A tire that has been filled with liquid can’t flex, and will cause more soil compaction.

• Economic pressures to till and plant a crop encourage farmers to get the job done, sometimes working in wet fields at the expense of the soil. For the sake of the soil, work in your driest fields first. Stay off of fields that are wet. Waiting just a couple of days to till or plant the soil will allow soils to dry off enough to reduce the possibility of compaction.

• Heavy axle loads, such as grain carts and combines, can cause deep soil compaction. Localize traffic to specific areas and stay in these as much as possible. This will keep soil compaction damage to a limited area, and you will only need to loosen up these areas. Unload at the ends of fields and unload your combine before it reaches the maximum capacity.

• When possible, incorporate no-till or minimum-till practices. Be aware that it may take soil many years to recover from soil compaction, so the soil may need to be deep loosened before going completely no-till.

For more information on tire selection and soil compaction, contact your local New Holland dealer.

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