The Collaborative International Dictionary of English v.0.48:

Spadeful \Spade"ful\ (sp[=a]d"f[.u]l), n.; pl. Spadefuls
   (sp[=a]d"f[.u]lz). [Spade + full.]
   As much as a spade will hold or lift.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spadeful
    n 1: the quantity a shovel can hold [syn: shovel, shovelful,
         spadeful]