Fungi

Fungi are vital soil inhabitants responsible for nutrient cycling, soil remediation, and linking vast swaths of soil (and plants) together. Within the fungi category are the mycorrhizal fungi. Mycorrhizae form a symbiotic relationship with plant roots. They connect with plants by growing directly into or between cells along plant roots and exchanging carbon (energy) for nutrients and water. The mycor-rhizal fungi extend a plant’s rooting area dramatically and funnel nutrients and water back to the plant. In exchange, the plant gives the fungus sugars (carbon) to use as an energy source, as fungi lack chlorophyll, the necessary green pigment in leaves that allows a plant to harvest the sun’s energy and convert it into sugars.

Protozoa

Protozoa are larger single-celled organisms, and analysis of them can indicate whether a soil is aerobic (containing oxygen) or anaerobic (lacking oxygen), depending on the type present. Protozoa are the amoeba-shaped animals that cruise through soil looking for bacteria to eat. The C:N ratio of bacteria is less than the C:N ratio of the amoeba. Because the C:N ratio is comparatively less in the bacteria, not all the nitrogen is required by the amoeba to live. The amoeba exudes excess soluble nitrogen absorbed from the bacteria through its cell wall. This watersoluble nitrogen can then be taken up by plant roots or used as food by other microbes.

Fishing Fungi

The safari doesn’t end with bacteria and amoeba! There are fungi that create loops as they grow, in the hopes that a nematode will swim through the loop. In a split second, the loop tightens around the nematode and traps it in the grasp of the fungus. The fungus produces enzymes that break down the nematode into nutrients. The fungus can then absorb the nutrients into its body and the cycle continues. Not all the nutrients are absorbed by the 'fishing' fungus, and some of the nutrients are absorbed by other soil-dwelling organisms, by nearby plant roots, or absorbed back into the soil nutrient bank.

Nematodes

Then there are the nematodes. Nematodes are microscopic organisms that are long and cylindrical in shape with a wormlike appearance (they are nonsegmented roundworms, technically). Nematodes can be beneficial or parasitic. Beneficial nematodes protect plants by infecting insects and eating pathogens. In essence, the process is something like this: a nematode enters a host insect through any given opening or directly through the cell walls. Its secret weapon is the bacteria that live in the nematode’s gut. The nematode 'pukes up' the bacteria while inside the host insect. The bacteria begin to multiply and produce compounds that poison the host and turn the host body to a hot mess of insect goo—which is in turn eaten by the nematode, which then proceeds to multiply over and over due to the abundance of food. The cycle continues until all the food is gone, then the new nematodes burst forth to enter the soil solution and repeat the cycle.

Composted animal manures are nutrient-rich soil amendments.

Compost is the duct tape of the garden. It fixes nearly any problem: poor drainage, dense structure, low nutrient availability. It’s always a good idea to add compost to a new garden bed.

Piles of compost at commercial operations heat up to temperatures high enough to kill disease pathogens and weed seeds, plus quickly produce compost.

Passive composting is a good way for home gardeners to make their own compost.