The Collaborative International Dictionary of English v.0.48:

Agronomic \Ag`ro*nom"ic\, Agronomical \Ag`ro*nom"ic*al\, [Cf. F.
   agronomique.]
   Pertaining to agronomy, of the management of farms.
   [1913 Webster] agronomic

The Collaborative International Dictionary of English v.0.48:

agronomic \agronomic\ agronomical \agronomical\adj.
   1. 1 of or pertaining to agronomy.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

agronomic
    adj 1: of or relating to or promoting agronomy [syn:
           agronomic, agronomical]