The Collaborative International Dictionary of English v.0.48:

Agriculturist \Ag`ri*cul"tur*ist\, n.
   One engaged or skilled in agriculture; a husbandman.
   [1913 Webster]

         The farmer is always a practitioner, the agriculturist
         may be a mere theorist.                  --Crabb.
   [1913 Webster]

WordNet (r) 3.0 (2006):

agriculturist
    n 1: someone concerned with the science or art or business of
         cultivating the soil [syn: agriculturist,
         agriculturalist, cultivator, grower, raiser]