The Pumpkin Farm is used to plant pumpkins and melons and can be used to plant both at the same time. Each time that a pumpkin or melon grows and is harvested, a block of untilled dirt is left behind, and the Pumpkin Farm feels the need to keep this block tilled (despite the fact that this is not necessary for pumpkin or melon growth) at the cost of one block of Dirt. One block of Sand is produced every time that this action is completed. As such, the Pumpkin Farm needs a constant supply of Dirt if it is being run automatically.
Unlike other farms, which clear out a section of land (e.g. 13x13) and leave an area (e.g. 7x7 or 9x9) hollow for machines, sorting, storage etc., and using the outer hollow ring for planting, the Pumpkin Farm clears out a 13x13 area and leaves a 3-block wide strip in the center of the farmland available for use.
By using BuildCraft Pipes and a Pumpkin Harvester to pick the Pumpkins and Melons, it is possible to fully automate the process of pumpkin and melon farming, although a constant supply of Dirt is needed as is someplace to store excess Sand generated by the Pumpkin Farm.
This video shows an alternative to pumpkin/melon farming using redpower:
This video demonstrates how to use all forestry farms, including the Pumpkin Farm.