Understanding Soil CompactionPosted in: Farming By Elston Solberg November 23 2015
When I travel the world, either physically or virtually, I see technologies employed that should be used here. Liming, drainage, foliar fertility, multiple pass nutrition, surface soil structure modification, drip/sub irrigation, analytics, are all examples of technologies that could make a huge difference to grower’s bottom lines. This article addresses a grower/Agri-Coach question about compaction alleviation.
Agri-Coach Denis Vermette, owner of Ag Success Strategies out of Winnipeg Manitoba, has a client who was looking at possibly doing some subsoiling and was asking for some advice.
I say yahoo…
In many locations, subsoiling is such a common practice that people often don’t know any more exactly why they are doing it but its working. For me, this practice is all about battling compaction. Almost every field we cast our shadows on, there are 2 or 3 compaction zones:
• 2 man-made, a thin shallow shear zone from tillage/seeding equipment and a deeper, thicker one from equipment traffic.
• plus in certain soils, Mother Nature has left us with inherent compaction (Solonetz, Luvisols, etc).
Compaction messes up numerous functions such as water movement, water-holding capacity, root growth, nutrient availability and denitrification, and when encountered elsewhere on the planet, it is tackled by growers seeking to improve. In dryland North American agriculture, certain geographies have embraced this practice but many have not for reasons real or perceived – cost, lack of knowledge, bad experiences, etc.
1. Rip too deep and/or at the wrong time or year often with little/no background soil information.
2. Disturb too much soil and bring up subsoil that messes up the future seedbeds.
3. Forget they ripped and next year having trouble setting seed depth or getting stuck. Ripping is a dramatic intervention…the field should be ‘softer’ that’s part of the reason we rip to get rid of compaction or hardness.
For me, a ripper that is relatively narrowly spaced with low surface disturbance that has the ability to be modified with deep injection of nutrients is the way to go. The AgroPlow is 13", the DMI is 16" and other options exist. Grower will need precision GPS and the understanding that 2 passes are needed to “fix” fields. It took 80–100 years (10,000 with Mother Nature) to create these issues, so it will take some time to uncreate these issues.
The overly simplistic 7 step checklist for successful ripping:
1. Identify depth of compaction zones using a combination of penetrometer readings, moisture probing and small digs. From this we know how deep to rip, which is often MUCH shallower than anticipated, reducing time and diesel consumption.
2. Identify any potential issues at depth using soil survey information. These could include salts, carbonates, stones, elevated Na and/or Mg.
3. Narrow down potential issues by taking soil samples to at least the 24" depth.
a. What issues are there at depth that can complicate things?
b. Consider injecting Ca to keep fracture zone open longer and override negative effect of elevated Mg and/or Na at depth.
4. Rip when soil is dry…usually in the fall after a big crop. Start with the deeper thicker zone and target the opener at the middle of this compaction layer.
5. Grow a root dominant, deep-rooted crop, so the roots will proliferate into the fracture zone, providing some biological stability to the fracture, keeping it open longer.
6. Adjust seeding depth and packing, and expectations the following year to accommodate softer seedbed. A ripped field will take a while to reconsolidate!!
7. And finally…don’t forget to amortize the cost of ripping over years of better crop yields and take into account the cost of doing nothing.
For more information you can reach Elston at firstname.lastname@example.org.
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