The Collaborative International Dictionary of English v.0.48:

Tillage \Till"age\, n.
   1. The operation, practice, or art of tilling or preparing
      land for seed, and keeping the ground in a proper state
      for the growth of crops.
      [1913 Webster]

   2. A place tilled or cultivated; cultivated land.
      [1913 Webster]

   Syn: Cultivation; culture; husbandry; farming; agriculture.
        [1913 Webster]

WordNet (r) 3.0 (2006):

tillage
    n 1: arable land that is worked by plowing and sowing and
         raising crops [syn: cultivated land, farmland,
         plowland, ploughland, tilled land, tillage,
         tilth]
    2: the cultivation of soil for raising crops