Disc harrows - types, selection and proper tillage for higher yields

Disc harrows - types, selection and proper tillage for higher yields

03.06.2026

Post-harvest tillage is one of those steps that determine the yield long before a single seed hits the ground. The disc harrow is the tool that seals in moisture, chops stubble and prepares the topsoil for the next crop. Choosing the wrong harrow means shallow work on heavy soil, wasted fuel and excessive strain on the tractor.

This article covers the specific types of disc harrows, explains the differences between light and heavy models, between gang-type and individual-bearing designs, and sets out clear criteria for selection based on soil type, tractor power and farm size.

What is a disc harrow and what role does it play in farming

A disc harrow is a tillage implement consisting of steel discs set at an angle to the direction of travel. During work, the discs penetrate the soil, cut through plant residue and mix it into the upper soil layer.

Core functions of the disc harrow

Three main tasks make the harrow indispensable on any arable farm. First, chopping stubble and mixing it into the soil immediately after harvest. This prevents moisture loss and speeds up decomposition of crop residues. Second, pre-sowing preparation, where the topsoil is loosened and levelled for drilling. Third, weed control by provoking germination and then destroying the seedlings mechanically.

Why the disc harrow is irreplaceable

A plough turns the furrow. A cultivator loosens the soil. But a disc harrow does something neither can do alone - it cuts, mixes and levels the upper soil layer. That is why discing is often part of crop rotation planning, whether you grow wheat, maize or sunflower.

Types of disc harrows - light, medium and heavy

Classifying disc harrows by weight is not a formality - it directly determines which soils and tasks the machine is suited for.

Light disc harrows

Light models weigh up to 100 kg per disc. Working depth reaches 8-10 cm. They are suited to shallow stubble cultivation on lighter soils, surface refreshing and tillage on land that will be drilled shortly after harvest. They do not need a powerful tractor - 60-80 hp is enough for a 3-metre model.

Medium disc harrows

Weight ranges from 100 to 150 kg per disc. Working depth is 10-15 cm. This is the most versatile class, appropriate for the majority of arable farms. Medium harrows handle wheat stubble as well as the coarser residues from maize and sunflower.

Heavy disc harrows

Over 150 kg per disc, working depth up to 18-20 cm. Heavy disc harrows are designed for working heavy clay soils, breaking compacted layers and dealing with large volumes of crop residue. They require tractors in the 150-200 hp class and above.

Gang-type harrows versus individual-bearing designs

The way the discs are mounted is the second key difference between models on the market.

Gang-type construction

In a gang-type disc harrow, the discs are threaded onto a common shaft separated by spacer bushings. The advantage is lower cost and simpler construction. The drawback is significant - if one bearing fails, the entire gang must be dismantled. Crop residue also builds up along the shaft, requiring more frequent stops for clearing.

Individual-bearing design

In this configuration, each disc is mounted on its own hub with an individual bearing and spring or rubber damping. Replacing a damaged disc or bearing takes minutes without disturbing anything else. Residue build-up is minimal. The price is higher, but for operations with a heavy workload the difference pays for itself quickly.

Which to choose

For farms up to 300 hectares with predominantly light soils, a gang-type harrow is a sensible choice. For larger acreages, heavy soils and intensive use, the individual-bearing design is an investment that protects against costly downtime during the campaign.

Mounted and trailed harrows - when to use which

The method of attachment to the tractor determines manoeuvrability, transport width and maximum working width of the harrow.

Mounted disc harrows

Attached to the tractor's three-point linkage. Working width is usually up to 3-3.5 metres. The advantage is greater manoeuvrability and easier control from the cab. Suitable for medium-sized farms and irregularly shaped fields.

Trailed disc harrows

Connected to the tractor's drawbar with their own transport axle. Working width can reach 6-8 metres when unfolded. Intended for large acreages and powerful tractors. Road transport requires care due to the width and weight.

Hydraulic folding

Wider trailed harrows come with hydraulic folding, which reduces the transport width to 2.5-3 metres. This is essential for farms whose fields are scattered and require frequent road transfers.

Working depth and disc diameter

The two parameters that determine how deep and how aggressively the harrow works the soil are disc diameter and angle of attack.

Disc diameter

Standard diameters for disc harrows are 460, 510, 560 and 610 mm. A larger diameter means deeper penetration and better performance on heavy soils with heavy residue cover. For wheat stubble, 460 mm discs are adequate. For maize stalks and sunflower heads, 510 or 560 mm is recommended.

Angle of attack

The angle of attack is the tilt of the discs relative to the direction of travel. A greater angle produces more aggressive tillage - deeper penetration, more intensive mixing. A shallower angle gives lighter tillage and demands less draught force. Most models allow adjustment across a range of 12 to 24 degrees.

Notched versus plain discs

Notched discs cut through residue more easily and penetrate dry, compacted soil better. Plain discs leave a smoother surface after tillage and wear more slowly. For first-pass stubble cultivation, notched discs are preferable. For pre-sowing work, plain discs give a better finish.

How soil type determines harrow selection

Soils vary considerably - from light sandy types to heavy clays and chernozems. The disc harrow must match the ground it will work.

Light and medium soils

On sandy and sandy-clay soils, a light or medium harrow with 460-510 mm discs is sufficient. The discs penetrate easily, tractor load stays low and fuel consumption remains modest. Post-wheat and post-barley cultivation runs quickly and efficiently.

Heavy clay soils

Heavy ground demands a heavy disc harrow with discs of at least 560 mm, an aggressive angle of attack and enough self-weight to reach the required depth. A light harrow on clay simply slides across the surface without achieving anything useful.

Stony ground

Where stones are present, choose a harrow with individual-bearing hubs and spring protection on every disc. In a gang-type design, an impact with a stone transfers stress across the entire shaft, which can lead to bending or breakage.

Tractor compatibility - power and linkage

Before buying a disc harrow, do a simple calculation - whether your tractor can pull it and whether the linkage can lift it.

Power requirement

As a guideline, each metre of working width requires 20-35 hp of tractor power, depending on harrow weight and soil type. A mounted harrow with a 3-metre width needs at least 80-90 hp on medium soils. A heavy trailed harrow at 5 metres requires 150 hp or more.

Linkage category and drawbar

Mounted harrows need a Category II or III three-point linkage. Check the lift capacity - a heavy harrow can exceed the limit and damage the hydraulic rams. For trailed models, verify that the tractor has a suitable drawbar and that its braking system is adequate for the harrow weight during road transport.

Hydraulic requirements

Models with hydraulic folding and depth control require additional hydraulic sections on the tractor. Check that you have free quick couplers and that the hydraulic pump flow is sufficient for smooth cylinder operation.

Stubble cultivation - technique and timing

Stubble cultivation is an important agronomic measure. Doing it correctly preserves soil moisture and sets the stage for the next crop.

When to disc

Cultivation should be carried out as soon as possible after harvest - ideally within 24-48 hours. Every day of delay means moisture loss from the exposed soil surface. In summer heat, that loss can reach 5-8 mm per day.

Depth and working speed

The first pass is made at 6-8 cm depth. The objective is not deep tillage but sealing in moisture and chopping the stubble. Working speed is 8-12 km/h. Slower travel gives better mixing; faster travel saves time but compromises quality.

Second pass - when is it needed

With heavy crop residue (maize, sunflower), one pass is not enough. The second pass is made at right angles to the first and at a greater depth - 10-12 cm. A gap of 10-14 days is left between passes to allow weeds to germinate, so the second pass destroys them mechanically.

Pre-sowing tillage with a disc harrow

The disc harrow is not only for stubble. It is an effective tool for preparing the seedbed immediately before drilling.

Creating a fine seedbed

For pre-sowing work, the harrow operates at 4-6 cm depth with a reduced angle of attack. The goal is a fine tilth in the top layer where the seeds will germinate. For seed drills to work properly, the soil must be free of large clods and stones that prevent even seed placement.

Combination with a packer roller

Many disc harrow models are available with an integrated rear packer roller that consolidates and levels the soil after the discs pass. This combination eliminates a separate rolling pass and ensures optimal seed-to-soil contact at the subsequent drilling.

Disc harrow maintenance - discs, bearings and frame

Proper maintenance of the harrow extends its service life and reduces expenditure on spare parts.

Disc inspection

After every season, measure the disc diameter. Wear is normal, but once the diameter has decreased by more than 15-20 per cent of the original, the disc should be replaced. Unevenly worn discs cause side-pull and uneven tillage.

Bearings and seals

Disc bearings operate under extremely harsh conditions - dust, moisture, impacts. Check them before each season for play and noise. On gang-type harrows, replacing a bearing requires dismantling the entire gang, so it makes sense to replace all bearings on the gang at the same time.

Frame and bolted joints

Inspect the frame for cracks, especially around weld points. Check all bolted joints for tightness. A bolt that works loose in the field under load can cause serious frame damage.

Common mistakes in selection and operation

Experience shows that most problems with disc harrows stem not from the machines themselves, but from wrong selection or improper operation.

Too light a harrow for heavy soil

The most frequent mistake is buying a light harrow for clay soil in an attempt to save money. The result is surface skating, incomplete tillage and double the number of passes - meaning double the fuel and time. In the end, the cheap option proves expensive.

Working in excessive moisture

Discing wet soil is destructive. Instead of loosening, the harrow smears and compacts the ground, creating a so-called plough pan - a hard layer that restricts roots and water infiltration. If soil is sticking to the discs and forming lumps, stop and wait for it to dry.

Neglecting maintenance

A worn disc does not just till poorly - it loads the bearing unevenly and destroys it prematurely. A loose hub causes vibrations that crack the frame. Ten minutes of inspection before work saves hours of repair and hundreds in parts costs.

Frequently asked questions

What is the difference between a light and a heavy disc harrow?

A light harrow weighs up to 100 kg per disc and works to a depth of up to 10 cm - suited to shallow stubble cultivation on lighter soils. A heavy harrow exceeds 150 kg per disc, reaches 18-20 cm depth and handles clay soils and heavy crop residue.

Can discing replace ploughing?

Under certain conditions, yes. For crops that do not require deep tillage (for example, oilseed rape after wheat), double discing at 12-15 cm can replace the plough. You save fuel and time, but this only works where the soil structure is good and there is no deep compaction.

How many hectares per hour does a disc harrow cover?

It depends on working width and speed. A 3-metre harrow at 10 km/h covers roughly 2.0-2.5 hectares per hour. At 5 metres, around 3.5-4.0 hectares. Subtract 20-25 per cent from these figures for real conditions with headland turns, stops and uneven terrain.

When is the right time for stubble cultivation?

Immediately after harvest - ideally within 24-48 hours. Every day of delay means soil moisture loss, which is critical for residue decomposition and the establishment of the following crop.

How can I tell that the discs are worn and need replacing?

Measure the diameter and compare it with the original. If the difference exceeds 15-20 per cent, the disc is due for replacement. Other signs are an uneven surface after tillage and increased side-pull of the harrow.