The Collaborative International Dictionary of English v.0.48:

Aration \A*ra"tion\, n. [L. aratio, fr. arare to plow.]
   Plowing; tillage. [R.]
   [1913 Webster]

         Lands are said to be in a state of aration when they
         are under tillage.                       --Brande.
   [1913 Webster]