The Disc Harrow Revolution: A Story of Soil, Steel, and Seedbed Perfection

While ploughing vast tracts of virgin soil has long sat at the heart of farming lore, it was never strictly required to get the land producing. Many successful early growers skipped the plough altogether and broke ground in a different way. Many of today's widely drilled crops, along with countless grains and grasses, were first coaxed from the earth using disc harrows rather than shares and mouldboards.

As tractors gained horsepower and capability during the first half of the last century, disc harrows matured alongside them. Across the Atlantic, soil conditions and scale encouraged a different thinking altogether, one that favoured direct disc work over heavy inversion ploughing.

The Rise of the Disc

The use of metal discs rather than shares can be traced back to North America, where the broad, sun-baked prairies demanded a tool capable of biting into tough ground without the enormous draft of a conventional plough. Once producers discovered how efficiently the disc could open soil and prepare a clean seedbed, its reputation spread quickly. Over time the same tool proved itself just as capable when adapted to smaller fields overseas.

Disc harrows were first used in North America and soon began proving their worth in Britain, with the angled discs being ideal for breaking up the clods of ploughed land to produce a seedbed in a single pass in good conditions. This early double-gang set arrived on an adequate tractor and demonstrated how much ground could be covered in a morning's work.

Initially, American imports such as those offered by International Harvester found their way into British hands through the 1940s and '50s. An ever-growing number of domestic companies picked up the lead, recognising that dependable disc cultivators had a permanent place on modern farms. Well-known British names that adopted the idea included Ransomes, Petit and Bonehams. Once trailed implements met the dawning tractor era, disc harrows increasingly shifted away from being towed behind a draught horse to being drawn by smaller petrol and paraffin-fuelled tractors. Before long, rubber-tyred machines took over entirely.

Getting Larger

Most disc harrows were transformed from hand-hauled metal discs with a narrow side profile that ran through the soil at speeds of between 15 and 24 inches in diameter. These were upward six-foot apart on a shaft attached to the harrow frame with wooden bearings being replaced by longer-lasting metal roller bearings.

When maximum depth is required, the disc can be set parallel to the direction of travel, while a few forward-speed adjustments also assist the penetration in really tough conditions.

With the Ferguson TE-20 came a three-point linkage and draft control system that made fully-mounted disc harrows a reality. Ferguson offered a set to mount. Now the two trays enabling extra weight to assist with soil penetration. This Ferguson TE-D 20 is fitted with Bomfordian trucks to maintain traction.

The main running parts are of course, the discs, but also the bearings. The discs are usually made from hard-tested, high-carbon steel that's very hard-wearing. While the inner crease-shape tends to keep them sharp while at work, unless they get damaged. Chucking the state of the discs before work each day, and swapping any damaged ones, quickly becomes part of the daily routine for the tractor driver.

Power Takes Over

As tractors became more powerful, the most popular disc harrows moved from being fully-mounted back to trailed units, with hydraulically actuated transport wheels running on pneumatic tyres. Hydraulics also provided folding capability for the very large sets, enabling them to sit within the maximum width of the tractor to aid travel down the road.

An older set of Ransomes trailed disc harrows behind a Track Marshall Britannia crawler, showing the fitting of smooth discs on the front and scalloped discs on the rear.

There was a move away from disc harrows in the 1960s, when the power harrow arrived and began dominating the market. However, the arrival of the 1970s brought with it a greater interest in minimum cultivation techniques which, in turn, triggered a resurgence in the use of larger disc harrows. Typically, these featured a smooth-faced set of rear discs and a serrated front set, allowing them to chop through cereal stubble and other crop residue, and penetrate the soil more effectively while also incorporating the chopped material in the top layer of soil.

This was the period when truly large disc harrows began to appear, with larger-diameter discs and wider working widths, and it coincided with a growing interest in the larger, North American articulated 4WD tractors with their 200–300hp engines. These big machines and their implements used to follow the contours of harvest time, breaking up the stubble and turning-in the straw ready for a later pass and then drilling. However, many other farms that didn't subscribe to 'minimum tillage' continued with the larger disc harrows, encouraging the weeds and any spilt grain to chit and begin growing, then later be ploughed in, effectively buried and killed.

Deardens started by producing ploughs but soon moved on to other implements, including disc harrows. This large set of hydraulically-folding discs is seen on the back of a high-horsepower Caterpillar 75C rubber-tracked crawler.

With tractors like the Ford FW, MF 4000 Series and John Deere 30 and 40 Series giants on wide gangs of disc harrows, many British farmers began to resemble the plains of North America.

The Disc Plough

Used for many years in hotter climates around the world, the disc plough is exactly what the name implies; a plough with discs instead of shares. These are large, heavy-duty discs that turn over the soil in much the same way as a conventional plough. They comprise three to 12 scalloped discs in either fully- or semi-mounted configurations.

Since the late 1990s, though, many arable farms have moved away from simple disc harrows in favour of more specialist equipment offering rows of different cultivation techniques — mixing discs in with tines and packer rolls to produce a stubble-busting and consolidating tool that prepares the land for drilling in just one pass. These often include larger tines at the front, followed by discs and then the packer roll to firm the soil down afterwards.

Disc Harrows Today

British manufacturers who've supplied a lot of success with disc harrows include Pettit, WJ Cooper, Ransomes, Simba and Dowdeswell. There were others, such as Parmiter and Opico as well as those supplying imported products such as Bomford. Many of these makes are still found in service today, especially on smaller farms. Increasingly, spare parts are still mostly readily available from specialist suppliers who also produce generic parts.

Since the late 1990s, though, many arable farms have moved away from simple disc harrows in favour of more specialist equipment offering rows of different cultivation techniques — mixing discs in with tines and packer rolls to produce a stubble-busting and consolidating tool that prepares the land for drilling in just one pass. These often include larger tines at the front, followed by discs and then the packer roll to firm the soil down afterwards.

A set of Simba disc harrows and power breaking stubble at a tillage demonstration in Norfolk, making good use of the John Deere 8520T rubber-tracked crawler's power that's pulling them.

Originally, there were very long pauses of equipment, which led to them being called 'tillage trains'. But, nowadays, many farmers use smaller, even mounted, machinery that does the same task with fewer rows of working parts. Larger and longer machines are also produced for bigger enterprises, and the leading names in this area now include Vaderstad, Lemken, Kongskilde, Pottinger, Sumo and Great Plains.

So the disc harrow certainly isn't dead, but it has evolved. It remains a very smart piece of equipment and many growers still rely on them. Farm-scale contractors to be made and there are plenty of operators who are happy to keep their older implements in working order.

Hydraulically-folding disc harrows, with springs to keep the four 'wings' under tension while at work, being used for breaking stubble on the back of an International Harvester 6388 articulated-chassis tractor.

With the rise in popularity of minimum tillage, disc harrows would often be used for stubble-breaking hitched to a following press, enabling a zig-zag as the limits to rip up the stubble and then consolidate the soil and residue ahead of the drill.

From the sunbaked prairies of the American Midwest to the hedged fields of rural Britain, the humble disc harrow has quietly shaped the soil beneath modern agriculture. Its story is one of adaptation, resilience, and relentless usefulness — a tool that refused to be retired because it simply does the job better than almost anything else. Whether you're managing a homestead, a smallholding, or a serious working acreage, the disc harrow continues to earn its keep, one pass at a time.