Combating soil compaction
DEVILS LAKE, N.D. — Marla Riekman knows that farmers have many considerations in planting, nurturing and harvesting their crops. But she urges them to put soil compaction high on their things-to-consider list.
"We need to be deliberate how we travel on the field during field during field operations, particularly harvest," Riekman, soil management specialist from Manitoba.
She spoke Jan. 10 on the second and final day of the 37th annual extension Roundup farm show in Devils Lake. The event helps farmers and ranchers, primarily from north central North Dakota, learn more about a wide range of agricultural issues and topics.
Agriculturalists on the prairie of southern Canada and the northern Great Plains of the United States generally grow the same crops and face many of the same soil and climate conditions, including soil compaction.
When soil is compacted, soil particles squeeze together, restricting space available for soil and water. Growing plants are unable, or at least struggle, to send down their roots into compacted soil. That limits their ability to take up nutrients and hurts yields.
"Plants are lazy," Riekman said in describing plants' failure to fully tap compacted soil.
She's been told that saying plants are "opportunistic" instead of "lazy" would be better, she said.
Estimating yield losses from soil compaction is difficult, however, Riekman said.
"I often get a call asking, 'How exactly is this going to impact my yields?'" she said. "I have zero answers for that."
That's partly because there are different types of compaction:
• Hard pan occurs just below the depth of tillage. Usually one to two inches thick.
• Shallow compaction affects the top six to eight inches of soil.
• Deep compaction is below eight inches in depth.
Farmers often are wary of causing compaction when soil is saturated, but working moist soil can be even more dangerous, Riekman said.
"When your soil is moist, that's when you're at your greatest risk," she said.
Nature and the passage of time help to restore compacted soil, but only slowly and to a limited degree. So agriculturalists need to consider what they can do themselves, Riekman said.
Using cover crops can help. They can alleviate compaction, reduce susceptibility to compaction and potentially help soils dry by lengthening the growing season, among other benefits, Riekman said.
Other steps farmers should consider to combat compaction:
• Check and maintain tire pressure.
• Reduce total axle load.
• Minimize the number of trips over a field.
• Use duals/large-diameter tires or tracks.
• Rotate deep-rooted, water-loving crops.
• Reduce tillage.
Another possibility is controlled traffic farming, which uses permanent wheel tracks where crop zones and traffic zones are separated. The traffic zones are heavily compacted, while the crop zones are not compacted.
The rationale is yield losses on the heavily compacted traffic zones are more than offset by yield gains from the noncompacted crop zones.
Riekman has another suggestion, one she realizes may be unappealing to farmers who have only a short period of time to plant, nurture or harvest a field.
"Make sure that any activity on the field occurs when soil conditions are good," she said. "When working in less-than-ideal conditions, try to decrease axle loads make sure tractor is performing optimally."