1. Functional Groups
Soil microorganisms can be classified into functional groups according to the biological function they take on in a given ecosystem. For example, “all microorganisms that act in the N cycle (e.g., diazotrophic, nitrifying, denitrifying, ammonifying and proteolytic bacteria, etc.) and C cycle (e.g., cellulolytics, amilolytics, proteolytics, etc.) are examples of functional groups''. Here, the focus is not the individual species themselves, but the role they play collectively in an environment. Regardless, all of the biological components or biological communities of soil such as plants, animals, insects, earthworms, nematodes, arthropods, protozoa, fungi, and bacteria, are crucial components of soil health.
2. Microbial Community
Because the microbial community or microbiome are responsible for much of the recycling and transport of nutrients and water that occurs in the soil, they too are essential for overall soil health and productivity. According to Cardosa et al., “a teaspoon of soil can contain a billion bacterial cells, several to hundreds of yards of fungal hyphae, thousands of protozoa, and 10-20 nematodes (Ingham, 2018).”. As an example of some of the benefits of this microbial community, Rhizobium bacteria fixes nitrogen in legumes such as soybeans. Arbuscular mycorrhizal fungi (AMF), a group of beneficial fungi, form close bonds with plants and help them absorb nutrients.
3. Soil Biological Buffering
Contrary to chemical and physical properties, soil biological components can help with resistance, which is the ability of communities or populations to remain unchanged when stressed by a disturbance. Because “soil with high microbial diversity has more chance to keep the ecological processes after a disturbance.”.
4. Biochemical Indicators
Besides microbial activity and biomass, biochemical indicators i.e. soil enzymes, are another useful indicator of soil health. They are similarly responsive to changes in soil use and management. During carbon and nutrient cycling in soil, enzymes act as catalysts in different reactions. Additionally, soil respiration, production of carbon dioxide via soil organisms, has also been used widely as a bioindicator of soil health.
5. Importance of Biological Properties
“Biological properties” as expressed by one noted agronomist “are a forgotten and neglected dimension during more than a century of intensive agriculture practises.” But now that biological properties have gained more and more scientific evidence to support their importance, we can arrive at the conclusion that a combination of all three properties will ultimately lead to ideal soil health and productivity.
A Symbiotic Network
This key passage sums up the interactivity of the three components brilliantly: “The soil microbiome is truly a very dynamic, active, and diverse community. The microbial community performs much of the activities of breaking up and recycling plant residues, and capturing nutrients and water. The bacteria and fungi form close interactions with plants, creating symbiotic relationships that benefit both the plants and the microbes. The microbes mine nutrients and water from the soil and transfer these to the plants. In turn, the plants release sugars (carbohydrates) that the microbes need for an energy source. This dense, symbiotic network is the key to soil health.”
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