Born into Berkshire gentry, Tull studied law at Gray's Inn in preparation for a high flying political career. However, continuing illness stalled these plans and, after his marriage in 1699, he began farming with his father in Wallingford. He was not a natural: he hated the work and resented the reduction in profits caused by his labourers' salaries.
At the time, cereals were distributed into furrows ('drilling') by hand. However, Tull had noticed that traditional heavy sowing densities were not very efficient so he instructed his staff to drill at very precise, low densities. By 1701, his frustration with their lack of co-operation prompted him to invent a machine to do the work for him.
Inspired by the memory of an organ he had once taken apart, he designed his drill with a rotating cylinder. Grooves were cut into the cylinder to allow seed to pass from the hopper above to a funnel below. They were then directed into a channel dug by a plough at the front of the machine, then immediately covered by a harrow attached to the rear.
Initially the machine was only a limited success. In 1709 he moved to Prosperous Farm in Hungerford, and two years later decided to travel around Europe to improve his health and study agricultural techniques there. Upon his return in 1714, he perfected both his system and machinery. He pulverised the earth between the rows, believing that this released nutrients and so would act as a substitute for manure. While apparently successful - he grew wheat in the same field for 13 successive years without manuring - it is more likely that he merely prevented weeds from overcrowding and competing with the seed.
Eventually, as agricultural improvement became fashionable, more interest began to be taken in Tull's ideas. In 1731 he published his book, The New Horse Hoeing Husbandry, detailing his system and its machinery. It caused great controversy at the time, and arguments continued for another century before his eventual vindication. While several other mechanical seed drills had also been invented, Tull's complete system was a major influence on the agricultural revolution and its impact can still be seen in today's methods and machinery.