a 3 leg subsoiler

Delving Deep: An Essential Guide To Subsoiling

When it comes to successful farming, the ground beneath our feet holds more power than one might think. Tilling the topsoil is common practice, but what lies beneath could be affecting your crops in ways you haven’t considered. That’s where subsoiling comes into play, a method of deep tillage that revolutionises soil structure, optimises nutrient absorption and sets the stage for maximum yield.

In this comprehensive guide, we delve into the what, why, and how of subsoiling, focusing on its critical importance for growers, especially for those growing root vegetables like potatoes and swedes.

What It Is

Subsoiling is an advanced agricultural practice involving deep tillage to disrupt and loosen compacted layers of soil, usually ranging from 30 to 45 cm beneath the surface. The process is designed to enhance soil aeration, improve water drainage, and facilitate deeper root penetration, thereby optimising nutrient absorption for healthier, higher-yielding crops.

The Equipment

You’ll need a subsoiler implement, which attaches to the three-point linkage on your tractor. This device has one or more deep-ripping shanks designed to penetrate and break compacted soil.

A 3-leg subsoiler for grassland. The discs open the grass in front of the subsoiler leg and the wheels behind press it closed.

Detailed Steps


  1. Soil Testing: Identify soil compaction layers with a soil penetrometer.
  2. Moisture Assessment: Optimal soil moisture is crucial; too dry or too wet complicates the process.


  1. Attachment: Affix the subsoiler securely to your tractor.
  2. Calibration: Adjust the subsoiler’s shank to the desired depth, usually between 30-45 cm.


  1. Driving: Operate the tractor, ensuring the subsoiler cuts through the soil in straight lines.
  2. Overlap: Slight overlap between passes ensures thorough coverage.
  3. Speed: Maintain a consistent tractor speed for effective soil disruption.


  1. Field Walk: Inspect the field to confirm that the soil is properly fractured.
  2. Adjustments: Make necessary modifications to depth or overlap for subsequent passes.

Why It’s Essential

Enhanced Drainage

Subsoiling helps to break up hardpan layers or plough pans. This greatly improves water drainage. Improved drainage means less waterlogging, which is detrimental to crops like potatoes and swedes.

The bottom of the subsoiler leg is angled to break up hard layers of soil.

Improved Root Growth

Roots find it easier to penetrate deeper soil layers when the soil is less compacted. This enhances the plant’s ability to access water and nutrients, leading to more vigorous growth.

Nutrient Absorption

Compacted soil restricts root movement, limiting access to nutrients in deeper soil layers. Subsoiling allows roots to reach these untapped reserves, enhancing overall plant health.

A subsoiler working in stubble.

Increased Yield

Improved drainage, root growth, and nutrient absorption collectively contribute to higher crop yields. This is especially true for root vegetables, where the quality and size of the produce are directly related to soil conditions.

Soil Health

The aeration of the soil brought about by subsoiling promotes beneficial microbial activity. This, in turn, enriches the soil, making it more friable and enhancing its structure.

Environmental Benefits

Better water management reduces runoff, thereby decreasing soil erosion and nutrient leaching, which are environmental concerns.

Key Points for Farmers

  1. Horsepower Matters: Your tractor’s horsepower should match the requirements of the subsoiler. Underpowered tractors will struggle, making the process ineffective and potentially damaging your equipment.
  2. Soil Testing: Before proceeding, conduct thorough soil tests. These will help you identify the depth of compaction layers and guide you in setting your subsoiler to the correct depth.
  3. Timing is Crucial: The best time to subsoil is during drier conditions. Wet soil can lead to further compaction, while overly dry soil makes penetration difficult.
  4. Know Your Crops: Different crops have different root depths. Subsoiling depth should be adjusted according to the specific needs of the crops you are growing, especially important for root crops like potatoes and swedes.
  5. Safety First: Always adhere to safety guidelines, read the manufacturer’s instructions carefully, and use appropriate Personal Protective Equipment (PPE).
  6. Overlap Passes: For effective soil disruption, there should be a slight overlap between each pass of the subsoiler. This ensures you don’t miss any areas.
  7. Maintenance: Regularly check the subsoiler’s shanks and points for wear and tear. Keeping your equipment in top condition is crucial for effective subsoiling.
  8. Environmental Care: Subsoiling can reduce soil erosion and runoff, but it should be done responsibly to minimise any potential negative environmental impacts.
  9. Cost-Efficiency: While subsoiling has an initial cost, the improvements in soil health and crop yield often make it a cost-effective practice in the long term.


Subsoiling isn’t just another step in your farming routine; it’s an investment in the long-term health and productivity of your soil. For farmers who are committed to higher yields and sustainable practices, subsoiling offers a proven pathway. From breaking compacted layers to facilitating better nutrient absorption, this deep-tillage method opens up a world of benefits beneath your feet. As you strive for farming excellence, making subsoiling a part of your soil management strategy could be the game-changer you’ve been seeking