by Alan Jones
Farming is perhaps the oldest industry in the world. Historians are generally in agreement that the earliest implement was probably a crude pointed bent stick or tree branch which was used to stir and break the soil surface. In effect, a hand-held hoe in which the user scratched at the earth to bring nutrients to the surface and let moisture penetrate the soil. This would then produce a suitable tilth and condition in which seeds could be sown.
Existance became closely linked to the success of crops. By cultivating the soil, germination improved, crop yields increased together with crop quality.
Over 4000 years ago, those basic hand-held tools soon developed into simple ‘scratch’ ploughs. These primitive ploughs were pulled by oxen, camels or even elephants and in some instances even their women folk were used. Animals enabled the land to be tilled more easily and faster, subsequently, producing more food for their families. These ‘scratch’ ploughs continued to be used for thousands of years.
The primitive plough made an open shallow furrow, pushing soil away to either side rather than inverting it. The ancient Egyptians made considerable advance in its design. They also succeeded in growing many crop varieties in their dry arid climate by devising complex irrigation systems. As depicted on many of their monuments, the development of the plough from hand-held sticks to implements pulled by animals put them far ahead compared to other civilisations. However, the Greeks and Chinese were not so far behind and further developed the Egyptian ploughs with wheels. These were known as ‘crooked’ ploughs because the beam curved forwards towards the draft animal. The fitment of wheels provided greater control and manoeuvrability. Oak was used for the share beam, elm the draught beam and iron for the shares. Iron at that time was very precious so plough metal would be reshaped into weapons in times of war.
Eventually, the plough was developed to cut a long soil slice and turn it upside down, burying surface residue, conserving moisture, aerating the soil and killing weeds.
The Romans were very efficient with their conquering advances, but their ploughs were simple and crude. Although there had been enormous advances from simple stirring sticks for these early ploughs to produce well tilled soil, the land had to be cross ploughed at right angles to the first operation to ensure all the land was well prepared for sowing. Following the Romans, Anglo-Saxon law required every ploughman to make his own plough and that no one was entitled to use one unless they constructed it themselves.
The origin of the word ‘plough’ is difficult to determine as throughout Europe the spelling is similar - ‘plog’, ‘ploh’, ‘pflug’, ‘ploeg’, ‘plogr’ and old Saxon ’plog’. Ploughs were fastened to draft animals by their horns, tails and later using their shoulders to pull the implement through the soil.
There was little attempt to change the design of the plough until the mid-1600’s with the Dutch being among the first to improve its shape. The change in shape was soon discovered by many, however, in Northern England and Scotland this was further developed. Joseph Foljambe from Rotherham built and patented a plough having what was described as, the perfect implement then in use. Known as the ‘Rotherham Swing Plough’, because no depth wheel was used. It was constructed from a wooden frame with the fittings and coulter made of iron and the mouldboard and share covered with an iron plate. This new design was considered by all who saw it, to be more efficient and lighter to pull than any other kind at that time. For many years this design proved very popular and was used extensively up and down the country. It was perhaps the first to be factory produced on a large scale.
In 1763 a Berwickshire man, John Small, applied mathematical calculations and science to the mouldboard shape. He experimented with varying mouldboard curvatures and patterns, eventually producing a universal cast iron shape that would turn the soil more effectively with less force, wear and strain on the horse and ploughman. Over the years this ‘Scots Plough’ as it was known, was the beginning of the modern mouldboard plough.
Like our ancestors, we continued to find improvements. Since the mid 1800’s, there has been enormous change in plough development. Horse ploughs soon became redundant for more efficient steam units with large multi furrow balance ploughs. These ploughs were pulled by cable up and down fields, with only the sound of a steam whistle to indicate a change of ploughing direction.
Using converted horse ploughs, the more manoeuvrable wheeled tractor slowly took over from steam in the early 1900’s and was the start of the modern system we are familiar with today. In the 1920’s when Harry Ferguson’s 3-point linkage appeared it totally revolutionised implement attachment, machine control and performance. This system of attaching an implement to a tractor is now universally used throughout the agricultural industry.
We have witnessed many changes in plough design. For example; in the UK the conventional plough (right hand bodies only) has now been superseded by the reversible plough because of its simplicity of use and the ability to produce level fields. This being an essential part of current farming practices as larger and wider implements are being used. Sprayers, combine and sugar beet harvesters, to name but a few, would not perform to the high standards expected unless the cultivated land was level. Compared to the ploughs being used in the 1950’s and 1960’s we can pick out some major changes in design which have been necessary to cater for the needs and pressures of modern farming.
All modern reversible ploughs feature hydraulic reversing systems for turning the plough frame over at the headlands, from the left to the right-hand bodies and vice versa. Some are fitted with hydraulic change-over valves for automatic cylinder stroke direction. Those operators who used the early mechanical ‘push/pull’ or trip lever reversing system would not be able to rotate today’s ploughs as they are far bigger and heavier and often out of balance. Hydraulic reversal is assisted further with hydraulic main frame alignment. This allows the plough frame to hydraulically swing in line with the tractor to prevent the rear plough wheel from hitting the ground. It also improves stability and helps reduce the high forces imposed on both the plough and tractor during the reversing process.
Many years ago, if you had a 75hp tractor on the farm it was big and in most cases was only 2-wheel drive. We used to operate ploughs with 56 inches (1.42m) or 60 inches (1.52m) tractor wheel ‘centre-to-centre’ settings – not any more. Modern tractors feature 4-wheel drive and have wider wheel equipment with inside wheel settings up to 72 inches (1.83m). This is to transmit the high horse power available to the ground and keep the tractor in balance with equal weight on each wheel for maximum traction.
The tractor’s inside wheel setting controls the plough’s front furrow width when the tractor is operated with the right-hand wheels in the furrow bottom. For ease of plough setting, the plough must have a means of front furrow width adjustment to ensure the plough is compatible with the tractor wheel setting and the width of the other remaining furrows. In the days of conventional ploughs (using right hand bodies only), the front furrow width could be adjusted by sliding the cross shaft to the left or right or by rotating it. When rotated, it enabled the plough to be steered either towards the unploughed land or ploughed work, thus making the front furrow wider or narrower. Although some manufactures still use similar steering systems today on reversible ploughs, by angling the plough’s main frame, this is fundamentally wrong as it can cause the plough or tractor to ‘crab’ due to the increase or decrease in landside pressure. The correct way is to move the whole plough literally sideways at 90o to the direction of travel to change the width of the front furrow. This is achieved by using a simple slide and rail system or parallel linkage which moves the plough sideways with very little variation in landside pressure. It also allows for easy fitment of a hydraulic cylinder for ‘on-the-move’ front furrow width adjustment when working in hilly areas.
Over the years, furrow widths (‘X’) have increased from as little as 6 inches to over 20 inches wide. Back in the 1930’s horses and early tractor ploughs operated with furrow widths of 6 to 9 inches because of the limited power to pull them. The average width of a horse’s foot is around 7 inches therefore, when land was ploughed and subsequently sown, often by hand, onto what is termed oat seed furrows, the sown seed would roll and lay in the ‘V’ shaped furrow. The ploughing would then be cross harrowed covering the seeds with soil. Once germinated, the plants would be in rows of 7 inches apart, wide enough for the horse’s foot to pass between while walking through the established crop.
Early reversible ploughs were constructed from rectangular or rail line shaped solid steel bars. These were bolted together to form ‘A’ shaped sections to which the individual body assemblies and components were attached. Using this system on today’s larger and heavier multi furrow ploughs would cause distortion and poor body alignment. Modern plough frames are produced from a one-piece box section, heat treated for strength and to help keep the weight to a minimum. Manufactures without sophisticated heat treatment equipment use simple welded fabrications. These can be very heavy and impose additional high forces on the rear of the tractor.
A plough frame must withstand high twisting forces, especially when in a transport position, therefore, must be flexible to absorb the stresses and strains, yet rigid enough to maintain alignment accuracy.
The majority of early tractor mounted reversible ploughs had the furrow width fixed at 12 or 14 inches. To improve output efficiency and plough versatility, furrows had to get wider and be capable of being adjusted. This was not only to suit soil conditions, but to help reduce manufactures and dealers stocking levels. In the late 1970’s plough frames were being introduced with wedges, holes and parallel linkage to enable the furrow width to be easily changed. Output was the key factor and 16 inch ploughs began to appear from Europe. Often, we were told by our seniors, ‘you cannot plough wider than 14 inches’. They have been proved wrong, because ploughs are now capable of operating with furrow widths of over 20 inches wide. However, this was not possible without the development and changes to the shape of the mouldboard. With this change, it allowed for wider furrow slices and faster operating speeds. In the early 1980’s the patented Variable Width ‘on-the-move’ system became very popular. This was because of the simplicity to hydraulically change the furrow width from within the tractor cab to suit the type of soil being ploughed. As a result, output and ploughing efficiency improved as the operator was able to plough more acres a day.
A plough frame with bodies having an interbody clearance of 85cm (33.5in) and an under-beam clearance of 70cm (27.5in) or above is generally accepted as adequate for UK surface trash conditions, yet, many years ago we were using ploughs with as little as 20 inches between each body and 17 inches under the beam to the point. These early plough clearances would not allow the plough to perform at today’s ploughing speeds of more than 6mph or with the larger amounts of surface residue left over from the higher yielding crops.
All the latest mounted and semi-mounted ploughs can be equipped with either shear bolts, or auto-reset systems. These are to protect the plough from rocks and occasional obstructions. Plough legs fitted with a safety system is essential, because we are using very high horse powered tractors at faster operating speeds. Modern ploughs are also longer and heavier and do not ‘jump’ over obstacles as in the past. Modern steels and heat treatment processes also play an important part, because they have greater resistance to wear and can operate under tougher working conditions and at higher operating speeds without breaking. The old early ‘chilled’ cast iron shares would simply break.
Plough design has developed with civilisation and improvements in its efficiency as farm practices changed. Although, the plough is not used to the same degree as in the past due to the use of faster and more cost effective one-pass tined implements, its development will continue for eternity as man will always endeavour to find the ultimate solution in soil management for the efficient cultivation and inversion of the soil and production food.
Plastics or similar materials together with advances in electronics and automated machinery that ‘think’ as they operate is our future. What is revolutionary today will inevitably be overtaken by science tomorrow. It is a known fact; the mouldboard plough has a proven record for efficient soil management.
Good ploughing effectively inverts the soil, controls weeds, improves drainage, aerates the soil, improves the soil structure and reduces the risk of disease. Its use and development will continue to ensure it meets all the demands of farming in the future.
For further information on mouldboard ploughs and their settings ‘The Ploughman’s Hand Book’, a comprehensive guide to achieve and understand the fundamentals of the mouldboard plough and its use is available from The Society of Ploughmen. Click here for further details.