The amount of living microorganisms found in the soil is astonishing. Numbering in the trillions, microorganisms like bacteria, fungi, algae, and protozoa all have important roles to play in the development and growth of plants. Some microorganisms are useful for suppling plants with a useable form of nitrogen, while others provide food to larger organisms living in the soil, which too have a role to play in plant health. Let’s look at some of the microorganism found in soil and learn more about how they contribute to the growth and development of plants.
Bacteria
Bacteria play a major role in crop development as some types can turn atmospheric nitrogen into nitrogen-containing compounds like ammonia. This process is called nitrogen fixation, and without this process, most soils would not contain enough usable nitrogen to enable healthy plant growth. Not only are bacteria partly responsible for nitrogen fixation in the soil, they also perform many biochemical processes as well. Bacteria is the most abundant microorganism found in soil and they are great at breaking down organic matter that releases essential plant nutrients back into the soil.
Fungi
Fungi can be found living in soils all over the world. While their populations are dwarfed by the vast number of bacteria in the soil, they still play a critical role in the health and vitality of the soil. Just like some types of bacteria that can convert atmospheric nitrogen (N-fixation) into a form that is usable by plants, a certain type of fungi (mycorrhizal fungi) can also fix atmospheric nitrogen into a form that can be taken up by plant roots. Fungi also provides a food source for larger organisms living in the soil.
Protozoa
Protozoa are a type of microorganism that can reproduce sexually, which is different than spore duplication, as new genetics are introduced during sexual reproduction. Protozoa can be broken into three distinct groups called Flagellates, Amoebae, and Ciliates.
Algae
Algae may not be an organism that you think about living in the soil as its usually seen living in water, but algae do in fact live in soil as well. Some types of algae, like blue-green algae, can also perform nitrogen fixation that converts atmospheric nitrogen into a plant-usable form that can be taken up by plant roots. Algae is nowhere near as abundant in the soil as bacteria, but it too plays a critical role in providing usable nitrogen to developing plants.
Actinomycetes
Actinomycetes are a type of bacteria found in soil that have some similar characteristics to fungi, but they can produce antibiotics – something we use to help fight infections caused by other types of bacteria. Some of the antibiotics produced by actinomycetes include erythromycin, streptomycin, tetracycline, and neomycin.
The relationship between microorganisms and agriculture
Without microorganisms living in the soil, agriculture would be a very difficult venture. As we know, microorganisms living in the soil provide many benefits to developing plants, from nitrogen fixation creating a usable form of nitrogen that plants can use (ammonia), to organic matter breakdown that improves the physical structure of the soil. There is a special relationship between plants and soil microorganisms that has evolved over millions of years, and without it, there simply wouldn’t be life on earth as we know it today.