Nitrogen FixationNitrogen IsotopesNitrogen CompoundsNitrogen CycleBlood Urea NitrogenNitrogen DioxideReactive Nitrogen SpeciesNitrogen OxidesPII Nitrogen Regulatory ProteinsCarbonAmmoniaNitratesFertilizersQuaternary Ammonium CompoundsGlutamate-Ammonia LigaseUreaSoilNitrogen Mustard CompoundsNitrogenaseSymbiosisAmino AcidsBiomass