Soil Compaction

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Tractor tilling a fieldSoil compaction occurs anytime equipment passes through a field. Ideally, the distribution of solids and pore space will be 50% mineral and organic matter, 25% air, and 25% water. Compacted soils will have a higher percentage of solids and less pore space for air and water. The negative impacts of soil compaction include poor drainage, reduced seed germination, decreased root growth, decreased nutrient and water uptake, and overall reduced crop yield. There are ways to minimize soil compaction, however.

Tillage is the first option for many people when it comes to reversing the effects of compaction. Deep tillage is able to break up hardpans, but the effect it has on yield is variable. A hard pan is a compacted layer beneath the soil which very few roots can break through and is usually 1-2 inches thick. Also, be aware that continuous tillage like disking or plowing will cause a hardpan to develop just below the depth of the tillage and reduce soil structure. With the wide adoption of no-till equipment, many plows have been parked in the scrap yard.

The best way to deal with compaction is to avoid it in the first place. One of the fastest ways to compact soils is to drive equipment on wet or saturated soils. Clay soils, like the ones commonly found in Randolph County, are naturally prone to becoming hard when dry. Therefore, the majority of the fieldwork needs just the right amount of soil moisture before it can be done. Many times waiting for that adequate level it not an option and fieldwork happens anyways. That is when traffic patterns, axle load, and your equipment play a major part in minimizing soil compaction.

The majority of the compaction occurs on the tire tracks of the first piece of equipment that goes out in a season. Subsequent passes along that same tire track will increase compaction in that immediate area, but to a much lesser degree than a new path would. Therefore, whenever possible you should try to use the same tire track and path as previous equipment. This sometimes means matching equipment widths whenever possible or even adopting GPS guidance to pick up on previous lines. Never drive diagonally across the field. Higher tire pressure create compaction deeper than lower tire pressure. Using wider tires or adding more tires reduces the pounds per square inch exerted on the soil surface. Check manufactures specifications to get the tire pressure correct. With large equipment, if the weight per axle is too high then soil becomes more compacted deeper in the soil profile regardless if it’s a tire or a track. Keeping the axle weight lower will localize the compaction higher in the soil profile.

This is a basic rundown of compaction management. The details of what compaction management will look like on your operation is dependent on too many factors to cover in this article. Contact your local Extension agent if you would like to dive further into this subject or design a plan for management in the future. We did not cover compaction issues in pastures in this article. There is enough to cover on that subject to form another article, which we will do in the near future.