Around the roots of plants, there is a tiny world called the rhizosphere. While it may be small, it is not insignificant. In fact, the rhizosphere plays an important role in cycling carbon and nitrogen between bacteria, protozoa such as amoebae, nematodes (round worms), and the plant roots themselves. The easiest way to see the rhizosphere is by collecting water that drips out of the bottom of a flower pot and putting it under the microscope. You don’t need anything more than about 100x magnification to see all the players (except the bacteria, you won’t be able to see them at that magnification).

Naked Amoeba: One of the most important bacterial grazers. Its squishy body and pseudopods allow it to graze in the biofilm.

How does this little ecosystem work? Let’s start with the bacteria. Plants will release precious organic carbon (glucose or some sort of sugar) from their roots to feed the bacteria. As a result, the increase in bacteria population is controlled by grazers, microorganisms such as amoeba and nematodes that eat the bacteria. The consumption of bacteria increases the amount of nitrogen (in the form of nitrates and nitrites) in the soil. Since plants are able to utilize this form of nitrogen to grow their roots, it is in the best interest of the plants to feed the bacteria.

What is the significance of learning about the rhizosphere? In order to work towards more sustainable agricultural practices, it is important for farmers and agriculturalists to understand what happens when the rhizosphere is disrupted; perhaps there are ways to build a stronger or more resilient rhizosphere. Plants are also able to distinguish between beneficial versus harmful microorganisms and just to throw in an added layer of complexity into all this, fungus also play a role in the rhizosphere. The more we understand this micro-ecosystem, the better chance we have of finding ways to grow crops with less pesticides, insecticides, and fungicides.

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