Subsoiler Use and Adjustment

A subsoiler breaks hardpan below normal tillage depth. Getting the adjustment right is the difference between shattered soil and a field full of narrow slots.

Key points

A subsoiler fractures a compacted layer; confirm the layer first.
Set working depth just below the top of the dense zone and check it with a test hole.
Work only when the soil is dry enough to shatter.
Do not weld or modify shanks yourself.
Call 811 and stay within your tractor's rated pull and lift.

What does a subsoiler do?

A subsoiler pulls a narrow shank through the ground at depth, lifting and fracturing a compacted layer. It is often used under a row, in a field with a known pan, or in headlands and gateways where heavy traffic has packed the ground.

The aim is vertical fracture, a cracked and heaved zone above the point, rather than a clean slot. That outcome depends on moisture, speed, depth and shank design.

How do you set the working depth?

Aim to run just below the top of the compacted layer, not far past it. Dig a test hole to find where the dense layer starts and ends. Going far beyond it uses a lot of power and may bring up wet or poor subsoil.

Set depth stops or gauge wheels according to the manual, make a short pass and dig beside the track to check. Adjust and test again. This takes a few minutes and avoids a full day of mis-set work.

Keep a record of the depth that worked on each field. Next time you can start from a known setting rather than from scratch.

How do shank angle and point style affect the work?

Many subsoilers allow changes to the shank angle or point type. A more aggressive angle may pull harder or dive deeper, while a flatter one may lift and shatter better. Wings or points attached to the shank widen the fracture zone but add draft.

Follow the manufacturer's guidance for your model. Do not weld or modify shanks yourself, since stress cracks in a heavily loaded shank can fail suddenly.

Set the toolbar level front to back and side to side.
Check that all shanks are the same depth.
Inspect points and wear plates before each use.
Check shear bolts or trip mechanisms and replace with correct parts.

What spacing and speed work best?

Spacing depends on depth. Shanks that are too far apart leave unbroken ground between them. Too close and you pull harder than needed. Check your implement's manual or ask your extension office for typical practice in your soil.

Run at a steady, moderate speed. Too fast can throw soil and rebuild a smeared layer. Too slow may not lift the soil enough to crack it. Watch the surface: a gentle heave and cracking above the shank is what you want.

After the pass, walk the field and probe again. If the layer is still dense in places, note where, since those spots may be wetter, rockier or heavily trafficked and may need a different approach.

When should you subsoil, and when should you not?

Subsoil when the layer is dry enough to fracture. In moist, plastic clay you will only slot and smear. Subsoiling in wet spring ground on a 5-acre homestead garden is a common error that makes drainage worse.

Skip the job if you have not confirmed a pan. Also be careful on slopes where cracks can speed runoff and erosion. Ask your conservation district for local guidance.

A good rule is to treat subsoiling as a repair, not a routine. If you find yourself doing it every year, look at what is causing the compaction, such as wet-weather traffic or heavy equipment on soft ground.

What safety points matter with subsoilers?

Subsoiling loads a tractor hard. Check your operator's manual for the hitch, lift and pull limits, and keep ballast and tires set as specified. A deep shank that hangs up can stop the tractor suddenly or lift the front end.

Wear your seat belt under ROPS. Keep bystanders clear, lower the implement before dismounting and block it well before any work underneath. Call 811 before working near buried utilities, drain tile or irrigation lines.

When should you stop and get help?

If a shank is cracked, bent or loose in its mount, do not keep working. A failed shank under load can throw metal. Take it to a qualified welder or the dealer service department.

If your results are poor even after adjustment, ask your extension agent to look at soil moisture, compaction depth and traffic patterns. Often the fix is a management change, not another pass.

When to get help: Have cracked or bent shanks inspected by a qualified welder or your dealer service department. Your extension office can help you read soil conditions and decide whether subsoiling makes sense.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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