Difference Between Nitrification And Denitrification (With Diagram)

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What Is Nitrification?

In this process, the ammonia is converted into nitrate by the presence of bacteria in the soil. Nitrites are formed by the oxidation of Ammonia with the help of Nitrosomonas bacterium species. Later, the produced nitrites are converted into nitrates by Nitrobacter. This conversion is very important as ammonia gas is toxic for plants.

The reaction involved in the process of Nitrification is as follows:

2NH4+ + 3O2 → 2NO2– + 4H+ + 2H2O

2NO2– + O2 → 2NO3–

Conventional nitrification occurs in soils, sediments and aquatic environments. It is very important in agriculture, where it determines the availability of fertilizer nitrogen and in wastewater treatment systems where it participates in the removal of excess ammonia. In the marine environment, nitrification determines the form of nitrogen available for primary production in the surface layer. In natural systems, nitrification rates are determined by environmental factors such as salinity, temperature, oxygen and PH.  

Nitrification Process

Facts About Nitrification

  1. Nitrification is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate.
  2. Nitrification follows ammonification process.
  3. Nitrification is facilitated by two main types of chemoautrophic bacteria: Nitrobacter and Nitrosomonas.
  4. The process occurs at the PH range of between 6.5 to 8.5.
  5. Nitrification is an Oxidation type of reaction.
  6. Nitrification is the second step of the nitrogen cycle.
  7. Nitrification involves the conversion of reduced compounds into oxidized forms.
  8. Nitrification is a two step process- Conversion of ammonia to nitrite, then conversion of nitrite to nitrate.
  9. The substrate or the starting compound of nitrification process is ammonia.
  10. Many microorganisms perform nitrification under a high concentration of oxygen.
  11. The end product of nitrification is nitrate (NO3–).
  12. Examples of bacteria involved in this process include: Nitrosococcus, Nitrosopumilus maritimus and Nitrososphaera viennensis.
  13. The process occurs effectively at temperature range of between 16 oC and 35oC.
  14. Nitrification is inhibited by flooding, high salinity, high acidity, high alkalinity, excessive tilling and toxic compounds.
  15. Nitrification is an important process as it helps to provide nitrates to plants which act as a source of nitrogen.
  16. The overall reaction of nitrification is: NH+-> NO2–  ->NO3– 
  17. Nitrifiers are more sensitive to environmental stresses.

Also Read: Difference Between Aerobic And Anaerobic Respiration

What Is Denitrification?

Denitrification is the process in which the nitrogen compounds makes its way back into the atmosphere by converting nitrate (NO3-) into gaseous nitrogen (N). This process of the nitrogen cycle is the final stage and occurs in the absence of oxygen. Denitrification is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.

In nature, denitrification can take place in both terrestrial and marine ecosystems. Typically, denitrification occurs in anoxic environments, where the concentration of dissolved and freely available oxygen is depleted. In these areas, nitrate (NO3-) or nitrite (NO2-) can be used as a substitute terminal electron acceptor instead of oxygen (O2), a more energetically favorable electron acceptor.  Terminal electron acceptor is a compound that gets reduced in the reaction by receiving electrons. Examples of anoxic environments include: soils, groundwater, wetlands, oil reservoirs, poorly ventilated corners of the ocean and seafloor sediments.

Denitrification Process

Facts About Denitrification

  1. Denitrification is a biological process of reduction of nitrate into nitrite, which is then followed by the reduction of nitrate into nitrogen gas.  
  2. Denitrification process follows nitrification process.
  3. Denitrification is facilitated by heterotrophic facultative bacteria.
  4. The process occurs effectively at the PH range of between 7.0 to 9.0.
  5. Denitrification is a reduction type of reaction.
  6. Denitrification is the last step of the nitrogen cycle that releases nitrogen gas to the air.
  7. Denitrification involves conversion of oxidized nitrogen compounds into reduced forms.
  8. The process of denitrification occurs through a series of half reductions. There is conversion of nitrate to nitrite, then to nitric oxide, then to nitrous oxide and finally to nitrogen gas. 
  9. The starting compounds of denitrification process are nitrates and nitrites.
  10. Many microorganisms perform denitrification under a low concentration of oxygen.
  11. The end product of denitrification process is either nitrous oxide (NO2) or Nitrogen gas (N2).
  12. Examples of bacteria involved in this process include: Spirillum, Lactobacillus, Pseudomonas, Thiobacillus, Proteobacteria, Paracocus etc.
  13. The process occurs at the temperature range of between 26oC to 38oC.
  14. Denitrification is inhibited by reduced nitrification, lowered nitrate levels, deep placement of coated controlled-release fertilizer and soil drainage.
  15. Denitrification is an essential process as it ensures that there is cyclic movement of nitrogen from the atmosphere to the soil, plants and back to the atmosphere.
  16. The overall reaction of denitrification process is: 2NO3– +10e– +12H+ -> N2 + 6H2O
  17. Denitrifers are less sensitive to environmental stresses.

Also Read: Difference Between Nitrite And Nitrate

Difference Between Nitrification And Denitrification In Tabular Form

BASIS OF COMPARISON NITRIFICATION DENITRIFICATION
Description Nitrification is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate.   Denitrification is a biological process of reduction of nitrate into nitrite, which is then followed by the reduction of nitrate into nitrogen gas.    
Preceding Process   It follows ammonification process.   It process follows nitrification process.  
Facilitation The process is facilitated by two main types of chemoautrophic bacteria: Nitrobacter and Nitrosomonas.   The process is facilitated by heterotrophic facultative bacteria.  
Favorable PH Range The process occurs at the PH range of between 6.5 to 8.5.   The process occurs effectively at the PH range of between 7.0 to 9.0.  
Type Of Reaction It is an Oxidation type of reaction.   It is a reduction type of reaction.  
Nitrogen Cycle Position It is the second step of the nitrogen cycle.   It is the last step of the nitrogen cycle that releases nitrogen gas to the air.  
Role It involves the conversion of reduced compounds into oxidized forms.   It involves conversion of oxidized nitrogen compounds into reduced forms.  
Step Involved It is a two step process- Conversion of ammonia to nitrite, then conversion of nitrite to nitrate.   The process of denitrification occurs through a series of half reductions. There is conversion of nitrate to nitrite, then to nitric oxide, then to nitrous oxide and finally to nitrogen gas.   
Substrate The substrate or the starting compound of nitrification process is ammonia.   The starting compounds of denitrification process are nitrates and nitrites.  
Favorable Condition Many microorganisms perform nitrification under a high concentration of oxygen.   Many microorganisms perform denitrification under a low concentration of oxygen.  
End Products The end product of nitrification is nitrate (NO3–).   The end product of denitrification process is either nitrous oxide (NO2) or Nitrogen gas (N2).  
Bacteria Involved  Nitrosococcus, Nitrosopumilus maritimus and Nitrososphaera viennensis.    Spirillum, Lactobacillus, Pseudomonas, Thiobacillus, Proteobacteria, Paracocus etc.  
Favorable Temperature The process occurs effectively at temperature range of between 16 oC and 35oC.   The process occurs at the temperature range of between 26oC to 38oC.  
Inhibition It is inhibited by flooding, high salinity, high acidity, high alkalinity, excessive tilling and toxic compounds.   It is inhibited by reduced nitrification, lowered nitrate levels, deep placement of coated controlled-release fertilizer and soil drainage.  
Importance It is an important process as it helps to provide nitrates to plants which act as a source of nitrogen.   It is an essential process as it ensures that there is cyclic movement of nitrogen from the atmosphere to the soil, plants and back to the atmosphere.  
Overall Reaction NH+-> NO2–  ->NO3–     2NO3– +10e– +12H+ -> N2 + 6H2O  
Sensitivity To Environmental Stresses Nitrifiers are more sensitive to environmental stresses.   Denitrifers are less sensitive to environmental stresses.  

Importance Of Nitrogen Cycle

  1. Helps plants to synthesise chlorophyll from the nitrogen compounds.
  2. Helps in converting inert nitrogen gas into a usable form for the plants through the biochemical process.
  3. In the process of ammonification, the bacteria help in decomposing the animal and plant matter, which indirectly helps to clean up the environment.
  4. Nitrates and nitrites are released into the soil, which helps in enriching the soil with necessary nutrients required for cultivation.
  5. Nitrogen is an integral component of the cell and it forms many crucial compounds and important biomolecules.