Soil compaction: Silent yield thief

By John Fulton

John Fulton

Soil compaction continues to be a concern in Ohio as both precipitation during the spring and fall along with farm equipment size have dramatically increased the potential for compacting soils. Heavy farm machinery and tillage implements can magnify damage to soil structure reducing pore space between soil particles within the soil profile. While machinery weight is the primary culprit of soil compaction, the timing of field operations, in particular tillage and harvest, can have lasting impacts on crop yields if completed when field conditions are unfavorable.

Damage from soil compaction has significant impact on water infiltration, root development, nutrient uptake by crops and ultimately grain yield the following season. Research estimates that yield loss caused by soil compaction from machine traffic can be 10% to 20%. So as we move into the winter months and start prepping for spring field operations, it is important to evaluate if compaction exists within individual fields. There are four stages to soil compaction which include 1) identifying compacted areas, 2) evaluating these compacted areas to determine cause and severity, 3) preventative management to minimize future compaction, and 4) outlining strategies to manage existing compaction.

Two types of soil compaction exist: surface and deep compaction. Surface compaction occurs in the upper portion of the soil profile. It impacts emergence along with early crop growth and nutrient uptake but can be mitigated through different practices; most notable cover crops and tillage. Deep compaction occurs in the subsoil or deep in the soil profile. Deep compaction is long lasting and challenging since most of the time below the tilled layer.

The challenge with either types of these soil compaction is identifying and measuring them to understanding the level of severity. Signs of soil compaction can be looking for physical changes within fields, such as rutting. Coverage maps (i.e. as-planted, tillage, harvest) collected by technology can help identify areas to check. These coverage maps can be provide machinery paths across fields and the frequency or number of passes within areas of the field. Remoted sensed imagery can also be analyzed in-season to identify compacted areas and see if machinery traffic patterns exist. Reviewing yield maps can be a source for identifying and evaluating the impact of soil compaction. Additional indicators of compaction next spring can be non-uniform crop emergence or stunted growth of plants.

A good tool to have on hand to check for soil compaction and understand the level of compaction is a hand penetrometer. These tools measure soil resistance and can determine the depth of root restricting layers such as a plow pan layer. If wanting to collect quantifiable measurements with a hand penetrometer it is important to use when the soil profile is wetted up (i.e. at field capacity) and at a consistent speed (1 inch per second or 3 seconds per 3-inch increment on the rod).

In summary, soil compaction continues to hinder yields here in Ohio. Take time this winter to review maps or imagery to understand if soil compaction exists in your fields. If identified, a plan should be outlined for managing compaction in the future and how to mitigate it. These will be topics for the next article on soil compaction.

Learn more about soil compaction and research here at Ohio State University at the Ohio State Precision Ag website at https://digitalag.osu.edu/precision-ag/research-focuses/soil-compaction-management .

John Fulton is an Associate Professor and Elizabeth Hawkins is an Ohio State University Extension Field Specialist, Agronomic Systems. This column is provided by the OSU Department of Food, Agricultural and Biological Engineering, OSU Extension, Ohio Agricultural Research & Development Center, and the College of Food, Agricultural and Environmental Sciences.

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