The main difference between nitrification and denitrification is that nitrification is the process in which nitrogen is converted into nitrate whereas denitrification is the process in which nitrate is converted into nitrogen gas.
Nitrification vs. Denitrification
Nitrogen comprises around 79% of the atmosphere and an important part of protein and nucleic acid. It is a renewable resource which circulates on earth in a cyclic process known as the nitrogen cycle. This cycle is completed in five simple steps, i.e., nitrogen fixation, nitrification, assimilation, ammonification, and denitrification. Nitrification is the process in which ammonia is converted into nitrates while denitrification is the process in which nitrates are transformed into nitrogen gas. Nitrification is a type of reaction called oxidation reaction whereas denitrification is a type of reaction called reduction reaction. Chemoautotrophic aerobic bacteria facilitate nitrification while denitrification is facilitated by heterotrophic facultative bacteria. Nitrifiers are more sensitive to environmental stresses, but denitrifiers are less sensitive to environmental stresses.
What is Nitrification?
Nitrification is the biological process in which ammonia transform into nitrates by oxidation. Oxidation is the loss of electrons by a compound or an atom which results in an increase in its oxidation state. This action is performed by two types of nitrifying aerobic bacteria, i.e., chemoautotrophic bacteria of the genus Nitrosomonas that convert ammonia (NH3) and ammonium to nitrite (NO2–) and bacteria from the Nitrobacter group that convert nitrite to nitrate. These two reactions take place simultaneously and quite rapidly, i.e., within days or weeks. It is important to convert nitrite to nitrate in soils because nitrite is toxic to plant life and nitrates present in the soil are the primary sources of nitrogen for plants. The nitrifiers are more sensitive to environmental stresses and perform well at temperatures between 16 and 35 degrees C and pH between 6.5 and 8.5.
What is Denitrification?
Denitrification is that biological practice in which nitrate transform into nitrogenous gases by reduction. This action is performed by facultative anaerobic bacteria, e.g., Bacillus, Lactobacillus, Spirillum, Pseudomonas and Aerobacter, etc. These bacteria are heterotrophs, and they start denitrification as rapidly as minutes after the stimulation of the process. This process is useful for aquatic habitats and in sewage or industrial wastewater treatment. The denitrifiers are less sensitive to environmental stresses and perform well at the temperature between 26 to 38°C and at the pH between 7.0 to 8.5.
- The process in which ammonia is transformed into nitrate is called nitrification, whereas, the process in which nitrate is converted into nitrogen gas is called denitrification.
- Chemoautotrophic aerobic bacteria aid nitrification; on the other hand, denitrification is aided by heterotrophic facultative bacteria.
- Nitrification is a type of reaction called oxidation reaction. Conversely, denitrification is a type of reaction called reduction reaction.
- Ammonia is the precursor of nitrification, on the flip side, nitrate is the precursor of denitrification.
- The end product of nitrification is Nitrate, whereas, the end product of denitrification is Nitrogen.
- Nitrification requires aerobic condition, while, denitrification requires anaerobic condition.
- Nitrification occurs at pH between 6.5 to 8.5; on the other hand, denitrification occurs at pH range from 7.0 to 8.5.
- The temperature remains between 16 to 35 degree C during nitrification, while, it remains between 26 to 38 degree C during denitrification.
- Nitrification is inhibited by flooding, high salinity, high acidity, high alkalinity, excessive tilling and toxic compounds. Conversely, denitrification is inhibited by reduced nitrification, lowered nitrate levels, deep placement of coated controlled-release fertilizer and soil drainage.
- Nitrification is the two-step process: 1st is the conversion of ammonium to nitrite and 2nd is the conversion of nitrite to nitrate, on the flip side, denitrification involves the conversion of nitrate to nitrite, then nitric oxide, to nitrous oxide and finally to nitrogen.
- Nitrification grows slowly, while, denitrification grows rapidly.
- The nitrifiers are more sensitive to environmental stresses, whereas, the denitrifiers are less sensitive to environmental stresses.
- Nitrification provides nitrate to the plant, which acts as the important nitrogen source; on the other hand, denitrification is used in wastewater treatment and is beneficial for aquatic habitats.
From the above discussion, it is summarized that nitrification and denitrification are two important steps of the nitrogen cycle. Nitrification is an oxidative process that takes place in the presence of oxygen to convert ammonia to nitrate whereas, denitrification is a reductive process that takes place in the absence of oxygen to convert nitrate into nitrogenous gases.