The Collaborative International Dictionary of English v.0.48:

Batten \Bat"ten\ (b[a^]t"t'n), v. t. [imp. & p. p. Battened
   (b[a^]t"t'nd); p. pr. & vb. n. Battening.] [See Batful.]
   1. To make fat by plenteous feeding; to fatten. "Battening
      our flocks." --Milton.
      [1913 Webster]

   2. To fertilize or enrich, as land.
      [1913 Webster]