The process of converting nitrogen into nitrogen compounds by bacteria is called: nitrification denitrification decomposition transpiration

Nitrification is an aerobic process performed by nitrifying bacteria or archaea which transform ammonia into nitrite (NO2-) and then the nitrite to nitrate (NO3-). Nitrates are inorganic forms of nitrogen that plants can use as a nitrogen source so, the nitrification is an important step in the nitrogen cycle in soil.

(NH4 + → NO 2 - → NO 3-)