1) Nitrify 2) Nitrogenise 3) Process 4) Treat 1) Nitrogenise 
• (v. t.) To combine, or impregnate, with nitrogen or its compounds. • (v. t.) To combine, or impregnate, with nitrogen or its compounds.
Ni'tro·gen·ize transitive verb [ imperfect & past participle Nitrogenized ; present participle & verbal noun Nitrogenizing .] (Chemistry) To combine, or impregnate, with nitrogen or its compounds. 
nitrogenise verb treat with nitrogen or a nitrogen compound
to combine with nitrogen or add nitrogenous material to.