Nitrogen fixing bacteria can literally make nitrogen out of thin air! If you have these soil-based powerhouses in your garden, they will fertilize your plants for free. If you want to know more about the details of this process and how to make it work for you, read on.
There are several common soil bacteria that are capable of taking atmospheric nitrogen from the air and soil. Upon absorbing nitrogen as a gas, nitrogen-fixing-bacteria change it into nitrate or ammonia. Both nitrate and ammonia are plant absorbable forms of nitrogen that a plant can use. Plants use this nitrogen primarily to produce plant proteins.
The enzyme that is responsible for this nitrogen reduction process is called nitrogenase. It is found in specialized cells and microbial colony environments where there is no oxygen. Oxygen is known to destroy this enzyme through oxidation processes. There are many types of bacteria that can create specialized oxygen-free zones where they create nitrate and amonia.
Nitrogen Fixing Bacteria that Live on Plant Roots
The grandfather of microbial nitrogen fixation is the bacteria in the genus Rhizobia.
These bacteria form a symbiotic relationship with only legume plants, like soybeans, green beans, clover, and alfalfa. They form nodules on the root system.
Inside the nodule is an oxygen free zone where the nitrogenase enzyme reduces atmospheric nitrogen to nitrate and ammonia. The bacteria and the plant have a mutually beneficial relationship. The bacteria take certain food sources from the plant and in return they provide nitrogen to the plant.
(In this image you can see nitrogen-fixing nodules on clover roots.)
Nitrogen Fixing Bacteria that Live in the Soil
Another important type of bacteria that has the ability to provide nitrogen to plants is cyanobacteria. Cyanobacteria are beneficial bacteria in the soil that are free living. Cyanobacteria do not form nodules on plant roots. Instead, they work within the soil.
Nostoc commune is one type of cyanobacteria that can take nitrogen from the atomosphere and soil and transform it into nitrogen that plants can use. These cyanobacteria grow as chains of cells. On the chain, some of the microscopic cells will form what are called heterocysts. Inside the heterocyst is an oxygen free zone. The heterocyst is the place where the nitrogenase enzyme reduces atmospheric nitrogen to plant available ammonia. This ammonia is released into the soil chemistry and is then absorbed by plants.
The Easy Way to Use Nitrogen Fixing Bacteria
Although it may sound complicated, the bottom line is simple: If your soil is rich in nitrogen fixing bacteria, your plants will require much less nitrogen fertilizer.
America Natural sells the Soil Tech product, Microp, which is based on cyanobacteria as a biofertilizer soil inoculant. OMRI listed for use in organic agriculture, Microp is the easy way to put the power of nitrogen fixing bacteria to work in your garden.