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By Nancy Van Sas, OSCIA Workshop Leader, with contributions from Peter Johnson, Margaret May, and Cathy Dibble.

The Ontario Compaction Team, along with local farmers spent three days at Snobelen Farms, located on the east side of Brant County, testing the heavy Haldimand Clay soil compaction limits. The final day was open to the public as a Compaction Day on August 18, 2022, for spectators to view and learn about compaction, including the types, the associated problems, and some management strategies for reducing or correcting compaction.

In the last five years, there have been several compaction days held throughout Ontario. You might be asking yourself, “why is this compaction day different from any other?” As noted by Ontario Compaction Team member Margaret May, “since each of the Compaction Days are held in a different location on a different soil type, the results are different.” Haldimand Clay certainly proved this to be true as these soils reacted differently and challenged many of our beliefs in how compaction happens.

In the ten or more weeks leading up to the Compaction Day, the farm received little to no precipitation. The topsoil was crusted and dry. The expectation was that the subsoil would be equally dry due to the drought-like conditions. On the contrary, the Ontario Compaction Team found different results. According to team member Peter Johnson, these soils were acting like a muffin, with a hard brick-like crust on the A horizon (plow zone), but with a moist and compressible base, as there was moisture in the C horizon. Despite the drought, the heavy rains last fall recharged the soils and excessive moisture remained resulting in a soft and compressible subsoil. Johnson further noted that deep ripping in these conditions with equipment such as a subsoiler would negatively result in smearing rather than the desired lifting and shattering of the soils.

As noted above, at the time of the Compaction Day, the soils were very susceptible to subsurface compaction as a result of the excessive C horizon moisture. A water truck used earlier that week made a single pass in the field creating enough compaction that it appeared to be a heavily trafficked access laneway at first glance. This compaction was not visible on the surface, but only when a metre deep soil pit was dug on site to demonstrate the differences in the soil types for each soil horizon. A huge lesson learned that day was to DIG; dig a soil pit of your own to see what is truly going on below the surface. Mobile Soil Technology Suite (MSTS) Technician Cathy Dibble cannot stress enough the importance of spending the time to view what is happening below the surface as there are many factors to take into consideration that may not be visible.

Lessons Learned:

1. Compaction is complex

• There are no universal rules for compaction
• Each soil type compacts differently and is influenced by the presence or absence of moisture

2. There is surface compaction and subsurface compaction

• Low pressure tires and tracks aid in reducing surface compaction
• Reducing axle weight aids in reducing subsurface compaction

3. Dig before tillage

• Subsurface conditions are not evident on the surface
• A soil pit the depth of your equipment will expose subsurface conditions

4. Weigh your equipment

• Know your equipment weight to determine the appropriate tire and the correct pressure it should be running at in the field

5. Learn and experiment with compaction reducing strategies

• Ideally attend a local compaction day to see these different strategies on your own soils to identify what combination will work best
• Investigate how water moves and how roots grow in your soil type
• Conduct cover crop trials
• Discover the latest in tire technology

Once available, the results of this compaction day as well as other compaction research can be found at: fieldcropnews.com.

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