John Fowler (11 July 1826 – 4 December 1864) was an English agricultural engineer who was a pioneer in the use of steam engines for ploughing and digging drainage channels. His inventions significantly reduced the cost of ploughing farmland, and also enabled the drainage of previously uncultivated land in many parts of the world.

Fowler was born in Melksham, Wiltshire. His father, John Fowler senior was a wealthy Quaker merchant, who had married Rebecca Hull, and together they had three daughters and five sons, of whom Fowler was the third son. When he left school Fowler followed his father's wishes and began working for a local corn merchant, but when he came of age in 1847 he turned his back on the corn business and joined the engineering firm of Gilkes Wilson and Company of Middlesbrough. Amongst other things, the company was involved in building steam locomotives and colliery winding engines. The company built a number of locomotives for the Stockton and Darlington Railway.

Fowler might have remained with the Middlesbrough firm and made his reputation there, had it not been for a chance visit to Ireland in 1849, probably on business. This was at the time of the Great Famine, and Irish agriculture depended on the potato crop whilst much of the land was uncultivated due to poor drainage. This affected Fowler and he was convinced that there must be a way of bringing more land into production. The normal way to drain agricultural land was to use a mole plough to dig a subterranean drainage channel. The mole plough has a vertical blade with a cylindrical "mole" attached to the bottom. The mole is pointed at the front end, and as it moves through the soil, it leaves a horizontal channel into which porous drainage pipes can be laid. However this required considerable tractive power, so that the size of the plough was limited by the strength of the teams of horses that pulled it. Fowler returned to England and developed a horse-powered ploughing engine that would dig drainage channels.

Fowler's ploughing engine dragged itself across the field on rollers, pulling the mole plough as it went. The engine was driven by a team of horses that walked round a capstan, winding in a rope which was passed through a pulley securely anchored at the far end of the field. The mole would have a string of drainage pipes attached at the rear end and these would be dragged through the channel created by the mole. On completing each length of drains, the engine would be turned, the rope would be let out and the pulley repositioned ready for the next length. Fowler had trouble with the capstan gears and with the rope slipping on the capstan, but was able to demonstrate his engine at a meeting of the Royal Agricultural Society of England at Exeter in 1850. He was able to lay a drain at a depth of 2 ft 6 in (0.76 m) in heavy clay. His invention was awarded a silver medal and was reported as "altogether the most important feature of the exhibition."

Fowler then decided to change his design so that the horse engine remained stationary at the corner of the field. The team of horses drove a vertical winch around which a rope was wound. The rope would pass along the edge of the field to a securely anchored pulley and would then pass at right angles across the field to the mole plough. As the horses drove the winch, the rope would drag the mole plough across the field, digging a drainage channel and inserting a length of drainage pipes. When each length had been completed, the pulley would be moved to a new position, the rope would be let out and the plough would be taken to the far side of the field, ready to start the next channel. The design was a vast improvement on the previous one, in that the horsepower was not being expended in dragging the machine across the field, only the plough. Fowler demonstrated his new drainage plough at the Great Exhibition in 1851 and at the Royal Agricultural Society of England meeting at Gloucester in 1853, where he was awarded another silver medal. He was able to lay drains to a depth of 3 ft 6 in (1.07 m).

In his early career, Fowler had worked with steam engines and the logical progression was to apply this method of power to his drainage plough. This he did in 1852 when he designed a steam engine with a winch mounted out in front of the smoke box and a rope running from it, round a pulley anchored at the far side of the field and back to the engine. The engine pulled itself across the field, dragging the mole plough behind it. The design was therefore similar to his first design for the horse-powered plough. The experiment was a failure because the steam engine proved to be too heavy to move easily over soft ground. However, in the same year, on 21 October, Fowler was awarded patent number 480 for "Improvements in Machinery for draining land", believed to be one of the first patents for the use of steam power in agriculture.

Following the failure of his first steam-driven plough, Fowler reverted to the design used for his second horse-driven plough. His new design consisted of a steam engine placed in a corner of the field driving a winch. A rope led from the winch along the side of the field, around a securely anchored pulley and across the field to the mole plough. As the winch drew in the rope the mole plough was drawn across the field digging a drainage channel as it went. The engine also had a second winch with a rope passing round the same anchored pulley and then passing across the field and around a second pulley and back to the plough. This second rope would be used to drag the plough back to its starting point after completing a drainage line. Both pulleys would then be re-anchored at both ends of the next channel to be dug and the ploughing process would be repeated. The steam plough was demonstrated at the Royal Agricultural Society of England meeting at Lincoln in 1854.

It seemed an obvious progression to use Fowler's latest steam-driven plough for normal ploughing, rather than just drainage channels. However normal ploughing was much lighter work that could be achieved perfectly well by a team of horses and in comparison the steam-driven plough was rather cumbersome. One way of improving the plough's efficiency would be to design a plough that could plough in either direction without having to be turned round. Fowler achieved this by designing a frame for the plough that had two ploughs attached as a kind of see-saw. One of the two plough blades would be swung down to make contact with the soil, depending on the direction the plough was to travel. At the end of each furrow the anchored pulleys would be moved slightly ready for the next furrow.