Taking action on compaction: How to keep your soil healthy and stable

Soil compaction can be a large piece of the puzzle when it comes to determining your soils success.

What we know about soil compaction

Compaction is something all farmers have experience in managing and can largely impact crop yield. Compaction in soil reduces the amount of available pore space within the soil which impacts crop production as it limits the water holding capacity of the soil and reduces root growth, limiting nutrient uptake. Compaction most noticeably impacts crop yield during years of environmental stress like excessive moisture or drought. A common concern among growers on giving up tillage is that by going reduced or no-till on farm, they will no longer be able to properly manage compaction. There are, however, great ways to reduce the risk of compaction in the regenerative ag space that can help.

Research shows that crop yields can be reduced anywhere between 10 and 30 percent in extreme cases of compaction.  This can be caused by several factors including equipment traffic (axel load) and tillage. While tillage can relieve soil compaction temporarily, it is not a long-term solution as continued tillage can recreate the issue. This causes further compaction which is then amplified when soils are wet.

How do you search for signs of compaction?

• Water ponding in soil.
• Shallow rooting in crops.
• Platy soil structure.
• Nutrient deficiency.
• Uneven growth patterns in crops (especially following wheel tracks).
• Poor penetrometer readings (300 psi or higher means zero root growth).

Figure 1. Image of platy soil structure indicating soil compaction. Photo courtesy Damien Oien, Conservation Agronomist.

The above symptoms typically show themselves in combination when compaction is happening and should not be used as individual markers in diagnosing high soil compaction. Soils can self-repair to some extent but reducing tillage and changing your practice can help prevent compaction from being a continued problem.

Soil health practices can support you in managing compaction

Although compaction can have a largely negative impact on crops, there are strategies we can use to address the issue and change your soil structure. There are several strategies that can be considered but today we are going to focus on reducing tillage and adding cover crops. Remember that changes to soil compaction will happen over time.

A few quick ways you can start managing compaction:

• If you must till, avoid doing it when the soil is wet.
• Reduce trips across the field with high axel loads.
• Control traffic patterns in your fields.

Figure 2. Tire tracks are seen in yellowing soybeans. Compaction is reducing their ability to take up nutrients. Photo courtesy Anna Teeter, Conservation Agronomist.

Transitioning your farm to no-till reduces several factors that create compacted soils. It eliminates the need for further tillage practices as short-term solutions to compaction and reduces the number of tractor passes over fields. No-till soils are typically less dense because soil structure and pore spaces have had the chance to be preserved or rebuilt over time. These fields are also more stable and manage water better due to healthier soil aggregation and pore space.

Implementing cover crops into your rotation can also help reduce compaction as having a variety of root structures and depths helps to create more pores in the soil. This allows air and water to move more freely within the soil, reducing compaction. The roots also help to hold the soils together. There are several species that can help improve compaction including tap-rooted radishes and deep-rooted grasses like cereal rye or annual ryegrass.

Over time, no-till and cover crop systems tend to be more profitable and better at managing compaction than conventionally managed soils. If you’re concerned about how transitioning to no-till or reduced-till practices might impact your soil, reach out to your Cargill agronomist to discuss the benefits and potential risks. 

Resources:

https://extension.umn.edu/soil-management-and-health/soil-compaction

https://crops.extension.iastate.edu/cropnews/2016/07/soil-compaction-and-what-you-can-do-about-it

https://extension.psu.edu/diagnosing-soil-compaction-using-a-penetrometer-soil-compaction-tester

https://extension.psu.edu/effects-of-soil-compaction

https://www.usda.gov/media/blog/2017/11/30/saving-money-time-and-soil-economics-no-till-farming

https://www.no-tillfarmer.com/blogs/1-covering-no-till/post/8266-high-profit-or-high-yield

https://soilhealthinstitute.org/our-work/initiatives/economics-of-soil-health-systems/