A farm was an area of land used for agriculture. As the Second Doctor put it, it was "...where food is grown, where corn grows and where cows and sheep and pigs and so on eat so that they may give us milk and eggs and meat." (PROSE: Planet of Bones) People who worked on or owned farms were called farmers.
The Tenth Doctor told Martha Jones that he normally went to a farm in 9th century France for his milk. (COMIC: Wrath of the Warrior)
Also in that century, Viking village, after their best warriors were killed by the Mire, the Doctor only had farmers and peoples of other profession to train as warriors. (TV: The Girl Who Died)
In France in 1794, a farm was used as a safehouse for escaping counter-revolutionaries. The First Doctor's companions Susan, Ian and Barbara were captured by French soldiers while they were visiting the farm. (TV: The Reign of Terror)
In France in 1898, Alain and Simone's farm was threatened by an alien Bulb. (COMIC: The Mutant Turnip)
Clark owned Oakham Farm until his death in 1913. (TV: Human Nature)
Before the outbreak of the Spanish Civil War in July 1936, Juan Romero was a farmer. (AUDIO: Fiesta of the Damned)
The Second Doctor investigated Glenlock-Hogan's farm where walking scarecrows had been reported. (COMIC: The Night Walkers)
An injured Silurian took refuge in a barn on Squire's farm. (TV: Doctor Who and the Silurians)
Tegan Jovanka's father owned a farm in Australia. (TV: Logopolis)
The Eleventh Doctor and Amy Pond used a farm's pumpkins to stop an alien invasion led by Zargofly and Zarkon. (COMIC: The Trick)
In 2013, the Eleventh Doctor, Amy and Rory saved Gero and Chipo's farm from giant insects. (COMIC: Buzz!)
Vilgreth worked on a farm in Devon in his youth. (AUDIO: Last of the Titans)
On the Crooked World, Streaky Bacon owned a farm outside Zanytown. (PROSE: The Crooked World)
On Harmony, all farms and animals had been wiped out thousands of years before the Doctor arrived. (PROSE: Planet of Bones)
On Tír na n-Óg, Bathsheba's family worked on a farm until they were all killed by demons. (PROSE: Cat's Cradle: Witch Mark)