By Rafael Pérez Vicente
June 30, 2022
UPDATED 12:00 PM EST
Talking about soil usually involves people thinking of an abiotic factor in ecosystems and containing nutrients and minerals necessary for life. However, the case is somewhat different, some of the oldest living organisms on Earth appeared as early as 3.5 billion years ago, and their role in soil has been refined since that time. Ranging from different species of bacteria, fungi, protozoa, and other microbial communities, this microbiological ecosystem serves different purposes in the soil and its capacity to interact symbiotically with plants and roots. The diversity among soil and its microorganisms are enormous, it has been said that a spoon full of soil has roughly the same number of microbes as people on Earth.
MIcroorganisms in the soil have been famous for different reasons over the last few years. Initially, they play an important role in maintaining fertility and cycling of nutrients along the food chain. As an example rhizobium bacteria have the capacity of fixing nitrogen from the outer atmosphere to transform it into a usable form of nitrogen for plants. This gram-negative type of bacteria provides this important nutrient to the plant and aid with the cycling of nutrients.
Additionally, there has also been important evidence regarding microfungi and their role in the soil. This biological creature aids in the decomposition of soil and its fertility, as well as controlling plagues; and certain bacterial and fungic growths. Firstly, the Bacillus genus of fungi helps significantly contribute to the decomposition of organic matter in the soil, to make it available for plants in energy cycling in the food chain. This genus is known as saprotrophic for its ability to secrete external digestive enzymes that break down large matter into smaller pieces. On the other hand, Trichoderma, another genus of fungi, works with its beneficial capacities to control plagues and other pathogenic fungi and bacteria to avoid certain plant diseases or death. Both types of fungi directly contribute to the fixation of nutrients and minerals from the soil to the plant. Providing crops with higher nutrient content and of better quality.
Nevertheless, as there are benefits from microorganisms in the soil, there are also a few (or rather a lot) of disadvantages; as multiple biological organisms are pathogenic or harmful to the soil´s fertility. For instance, fungi such as the Fusarium present in most soils affect plants by causing certain diseases or infections that end up with nutrient deficiencies or even the death of the plant. Additionally, phytopathogenic bacteria has also a harmful effect on plants, as they cause spots in the leaves, rotting stems, and death.
Ultimately, the effect of microorganisms in the soil has an impact that is yet widely unstudied. Its consequences on the efficiency, health, and success of crops are still unknown, but they have been known to have a positive effect. The mutualistic relationship involving plants and microorganisms, exchanging nutrients for carbohydrates and usable forms of energy has given scientists a clue as to how soil fertility works. And the adoption of strategies to implement microorganisms back into the soil could be the key to restoring a healthy growing land.
[Photo Credit: Kelsey Amelia Bates]
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