👉 Nitrification is a chemical reaction in which nitrogenous compounds are transformed into nitrogen gas. It occurs during aerobic respiration, and it is one of the four main processes that occur in photosynthesis. Nitrification is an important step in the process of cellular metabolism because it facilitates the conversion of organic matter into energy-rich compounds, such as ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).