The Collaborative International Dictionary of English v.0.48:
Denitrify \De*ni"tri*fy\, v. t. [Pref. de- + nitrogen + -fy.] To deprive of, or free from, nitrogen. [1913 Webster]WordNet (r) 3.0 (2006):
denitrify v 1: remove nitrogen from; "Denitrify the soil" [ant: nitrify]