The Collaborative International Dictionary
Nitrify \Ni"tri*fy\, v. t. [imp. & p. p. Nitrified; p. pr. & vb. n. Nitrifying.] [Niter + -fy: cf. F. nitrifer. See Niter.] (Chem.) To combine or impregnate with nitrogen; to convert, by oxidation, into nitrous or nitric acid; to subject to, or produce by, nitrification.
Wiktionary
vb. 1 (context transitive English) to treat, or react with nitrogen or a nitrogen-containing compound 2 (context transitive English) to convert ammonia or similar compound to a nitrate by oxidation, especially by the action of a microorganism
WordNet
v. convert into nitric acid, nitrous acid, or nitrate, especially with the action of nitrobacteria
treat with nitrogen or a nitrogen compound [syn: nitrogenize, nitrogenise]
treat (soil) with nitrates [ant: denitrify]
[also: nitrified]
Usage examples of "nitrify".
Walking along in silence, they at last found Shaw working in a nitrifying field of Dutch clover not far from his residence.
I remember aright, we were once antagonists in print in a discussion on Nitrifying Bacteria.