Azotobacter: naturally replacing synthetic nitrogen

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  • Azotobacter: naturally replacing synthetic nitrogen

How can Azotobacter naturally replace synthetic nitrogen units?

Azotobacter is a bacterium that can fix atmospheric nitrogen and convert it to a form usable by plants. This ability is due to the presence of an enzyme called nitrogenase, which converts atmospheric nitrogen into ammonia.

Nitrogen is a crucial element for plant growth, but plants cannot use atmospheric nitrogen directly. This is why most fertilizers contain nitrogen in the form of nitrate or ammonium, which are forms easily assimilated by plants. However, the production of synthetic fertilizers requires significant amounts of fossil energy, making it a significant source of greenhouse gas emissions. 

By using Azotobacter for nitrogen fixation, farmers can reduce their dependence on synthetic fertilizers and thereby reduce their carbon footprint. In addition, biological nitrogen fixation by Azotobacter can help maintain soil fertility by providing a source of available nitrogen for plants.


It should be noted however that nitrogen fixation by Azotobacter is less efficient than the production of synthetic fertilizers. It is therefore important to combine biological nitrogen fixation with other sustainable agricultural practices to ensure sufficient food production while reducing greenhouse gas emissions.

Know how Azotobacter works to increase its effectiveness.

Azotobacter is a free-living bacterium in the soil, capable of moving to join the rice sphere of plants. This faculty of movement is expensive in energy, which Azotobacter will draw from the root exudates excreted by the roots of the plants. The population of Azotobacter is therefore all the more developed as the root system of the crops is important.


On the other hand, the activation of the enzymatic complex nitrogenase, transforming nitrogen from the air into nitrogen assimilable by plants, requires the bioavailability of 2 trace elements: iron and molybdenum. However, the pH of the soil acts directly on the natural availability of these two nutrients. If the first is available in an acid medium, the second will be mobile in a basic medium. Since the pH of a soil is linked to the nature of its parent rock, simultaneous bioavailability of iron and molybdenum seems difficult to obtain.


Faced with this observation, the use of a solubilizing bacterium such as Bacillus is essential to make these two elements assimilable. Bacillus being a PGPR bacterium, it also acts in synergy with the root system of plants to stimulate their development.



Combining Bacillus with Azotobacter is the way to increase the efficiency of nitrogenase and ultimately crop yields by reducing the use of synthetic fertilizers.