Answer: nitrify

AnswerCrossword Clue
NITRIFYTreat with element 7
NITRIFYOxidize by bacterial action
NITRIFYImpregnate with nitrogen.
nitrifyto treat or combine with nitrogen or its compounds
nitrifyto oxidize (certain compounds) to nitrites, nitrates, or their respective acids, esp. by bacterial action
nitrifyto combine with nitrogen
nitrifyto impregnate with nitrogen or nitrogen compounds