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Nitrification vs. Denitrification: What's the Difference?

Edited by Janet White || By Harlon Moss || Updated on October 27, 2023
Nitrification is the biological conversion of ammonia to nitrate, while denitrification is the reduction of nitrates back to nitrogen gas.

Key Differences

Nitrification is a biological process where ammonia is oxidized to form nitrites and then nitrates. This aerobic process is primarily performed by nitrifying bacteria. On the other hand, denitrification is the process where nitrates and nitrites are reduced to form nitrogen gas. This anaerobic reaction is facilitated by denitrifying bacteria.
Both nitrification and denitrification are vital parts of the nitrogen cycle, ensuring the transformation and movement of nitrogen within ecosystems. While nitrification adds nitrates to the environment, which can be absorbed by plants, denitrification ensures the release of nitrogen back into the atmosphere.
In terms of importance for agriculture, nitrification helps in making nitrogen from fertilizers accessible to plants in the form of nitrates. Conversely, denitrification can lead to a loss of nitrogen in agricultural soils, as the produced nitrogen gas escapes into the atmosphere.
Environmental concerns also surround both processes. Nitrification can result in nitrate leaching into water bodies, potentially causing eutrophication. Denitrification, while aiding in reducing nitrate levels, can lead to the emission of nitrous oxide, a potent greenhouse gas.
The conditions favoring each process differ. Nitrification requires oxygen-rich (aerobic) conditions and is often seen in the upper layers of soil or water bodies. Denitrification, in contrast, occurs in oxygen-depleted (anaerobic) environments, such as waterlogged soils or sediments.

Comparison Chart

Process Type


Primary Agents

Nitrifying bacteria
Denitrifying bacteria

End Products

Nitrogen gas

Environmental Conditions

Aerobic (oxygen-rich) environments
Anaerobic (oxygen-depleted) environments

Impact on Environment

Can lead to nitrate leaching
Can reduce nitrate levels but produce nitrous oxide

Nitrification and Denitrification Definitions


The transformation of ammonium ions to nitrites and nitrates.
In wastewater treatment, nitrification removes harmful ammonia.


An anaerobic process facilitated by denitrifying bacteria.
Waterlogged soils favor denitrification, leading to nitrogen loss.


A part of the nitrogen cycle converting ammonia to usable forms.
Nitrification ensures that plants have access to nitrogen in the soil.


The biological reduction of nitrates to nitrogen gas.
Denitrification in wetlands helps purify water by removing nitrates.


A two-step aerobic process involving nitrifying bacteria.
The aquarium's filtration system promotes nitrification to reduce ammonia levels.


The transformation of nitrate to gaseous nitrogen forms.
Denitrification can result in the emission of nitrous oxide, a greenhouse gas.


The biological oxidation of ammonia to nitrate.
Nitrification in the soil aids plants in absorbing essential nitrogen.


The reverse of nitrification, releasing nitrogen back into the atmosphere.
In the nitrogen cycle, denitrification balances the accumulation of nitrates.


A microbial-driven process in oxygen-rich environments.
Proper aeration enhances nitrification in aquaponic systems.


A microbial-driven process in oxygen-depleted conditions.
Ponds with limited oxygen often undergo denitrification.


To oxidize (an ammonia compound) into a nitrite or (a nitrite) into a nitrate, especially by the action of nitrifying bacteria.


To remove nitrogen or nitrogen groups from (a compound).


Which bacteria facilitate nitrification?

Nitrifying bacteria, such as Nitrosomonas and Nitrobacter, carry out nitrification.

What is the primary purpose of nitrification?

Nitrification converts ammonia to nitrites and then to nitrates, making nitrogen available to plants.

How do human activities influence nitrification?

Activities like agriculture can increase nitrification through fertilizer application.

How does nitrification impact water quality?

Excessive nitrification can lead to nitrate leaching, posing risks to water bodies.

Why is denitrification important for wastewater treatment?

Denitrification removes harmful nitrates from wastewater before discharge.

What chemicals inhibit nitrification?

Certain chemicals, like nitrapyrin, can inhibit nitrification to retain ammonia in soils.

How do aeration systems influence nitrification in ponds?

Aeration promotes oxygen-rich conditions, enhancing nitrification.

Can nitrification occur in water bodies?

Yes, nitrification can occur in oxygen-rich zones of water bodies.

How does temperature influence nitrification rates?

Higher temperatures generally enhance nitrification rates, up to a threshold.

Why is denitrification crucial in the nitrogen cycle?

Denitrification ensures nitrogen balance by returning nitrogen to the atmosphere.

How does soil pH affect denitrification?

Soil pH can influence the activity of denitrifying bacteria, impacting denitrification rates.

Is nitrous oxide always produced during denitrification?

No, while nitrous oxide can be a byproduct, denitrification often results in nitrogen gas.

Can human activities reduce denitrification rates?

Yes, activities altering soil conditions or water quality can impact denitrification.

How is denitrification influenced by carbon sources?

Denitrifying bacteria require carbon sources for energy, affecting denitrification rates.

Can agricultural practices enhance both nitrification and denitrification?

Yes, practices like fertilizer application can increase nitrification, but waterlogged conditions can boost denitrification.

What are the end products of denitrification?

Denitrification produces nitrogen gas, nitrous oxide, or a mix of both.

In what environmental conditions does denitrification typically occur?

Denitrification occurs in anaerobic or oxygen-depleted conditions.

Can denitrification cause nitrogen deficiency in crops?

Yes, excessive denitrification can lead to nitrogen loss, affecting crop health.

What role does nitrification play in acid rain formation?

Nitrification can release hydrogen ions, contributing to soil acidity and potential acid rain.

Is denitrification beneficial for reducing nitrate pollution?

Yes, denitrification reduces nitrate levels, but it can produce nitrous oxide, a greenhouse gas.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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