The Collaborative International Dictionary of English v.0.48:

Marl \Marl\, v. t. [imp. & p. p. Marled; p. pr. & vb. n.
   Marling.] [Cf. F. marner. See Marl, n.]
   To overspread or manure with marl; as, to marl a field.
   [1913 Webster]