Soil Compaction

For many years now, deep tillage implements have been suggested as tools that can be used to loosen soil and improve crop yields. These implements can provide some benefit by loosening soil compaction, but they are really prescription tools and not to be used at will. Similar to a prescription drug, if you don’t have a problem then the drug isn’t going to do anything. 

Prevention

Preventing soil compaction is a better than trying to fix the problem. There are a number of management options that can be implemented to try to minimize soil compaction.

• Some areas of the province are dry, but other areas have more soil moisture than is normal for this time of year. Watch soil moisture and try to stay off the field when it is wet. This is easily said but sometimes hard to do because harvest schedules dictate the crop must come off.
• Reduce the pressure on the soil. This can be done by attempting to keep axel loads below 5 tons per axel. Use radial tires at low inflation pressures to create a larger foot print.
• Reduce the traffic on the field. Load wagons or trucks on a road (if it can be done safely) or a lane. Carry heavy loads down one area instead of all over the field.

Diagnosis

Do you have a soil compaction problem? Before you pull out the deep tillage implement, take some time to determine if soil compaction is really the problem. It is relatively easy to determine if you have a compaction problem. Using a tile probe or similar rod, probe the area to a depth of 50 cm (20 inches). Compare to a fence row or unaffected area. The tile probe should be slowly inserted into the ground at a steady speed. Your arms should be slightly bent, acting as the pressure gauge measuring the force required to push the tip of the probe through the soil. Record depths at which the tip of the probe requires more force to get it through the ground. This can be done by stopping when the probe reaches the layer with more resistance, putting your fingers around the probe at the soil surface and removing the probe to see the depth. It can be repeated at the bottom of the layer.

You can also use a shovel to dig up plants in an affected area. Look at the roots and compare to roots of plants in a healthy unaffected area. Compacted areas will have plants with malformed or restricted roots. Roots in a compacted area may also be concentrated in the top few inches of the soil. Make sure the areas you compare with the probe have similar soil moisture levels.

If you detect an area that you believe is compacted, it is a good idea to dig down to that area and confirm. Sometimes there can be a soil texture change which slows the probe and is not a compacted layer. Also, if the soil compaction is at a depth below 12-14 inches, there is not much you can do about it with tillage.

Remedial Measures

If you have determined that there is a compacted layer at a depth that you can do something about, then you can consider remedial measures. Deep tillage is an option. It should be done when the soil is dry, with an implement that will shatter the soil. Ideally, a cover crop should be planted following the operation that will put roots down to help keep the soil cracks open.

It is important once the tillage is done to avoid the practices in the future that caused the compaction in the first place. A non-tillage option is to plant a deep-rooted crop to penetrate a compacted area.

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