What’s Brewing is a podcast all about compost tea hosted by Troy Hinke.
Troy Hinke served as Rodale’s Compost Research Specialist alongside the founder of Soil Foodweb Inc., Dr. Elaine Ingham. Troy now runs Living Roots Compost Tea, where he offers several services including consultations, compost sprays, and compost brewing, among others.
Episode two of a 10-episode series on compost teas, host Troy Hinke talks about the soil food web: what it is, who’s involved, and how it works.
What is the Soil Food Web? (01:35)
The soil food web is the very beginning of the food chain, all made possible by microorganisms. The soil food web is built upon the symbiotic relationship between plants and microorganisms. Plants photosynthesize, turning sunlight into energy, and feed microorganisms, which will then provide nutrients to future plants.
Bacteria, mostly rods and cocci, play a role in the soil food web by decomposing low carbon and nitrogen material—green waste that are easy to decompose such as grasses, small green weeds, food waste, and hay.
Saprophytic and mycorrhizal fungi also have a place in the soil food web, as they decompose higher carbon and nitrogen material such as sticks, paper, leaves, cardboard, and straw. Mycorrhizal fungi also form symbiotic relationships with 90-95% of terrestrial plants.
Protozoa, which include testate and naked amoeba and flagellates, are predators that eat bacteria, which then release the nutrients stored in the bacteria’s bodies. Ciliates are also a type of protozoa, but their presence indicates low oxygen or anaerobic conditions—which we try to avoid when brewing compost tea.
Despite attaining a bad reputation due to root-feeding nematodes, nematodes still have a valuable place in the soil food web as predators that eat bacteria, fungi, or other nematodes, which helps cycle the nutrients from the bacteria into the soil in a plant-available form in the rhizosphere. Root-feeding nematodes are parasitic nematodes that feed on plants’ roots. Luckily, there is a type of nematodes called the predatory nematodes, which are commercially available and prey on these root-feeding nematodes.
Then, we have the bigger insects such as mites, springtails, arthropods, moving up to worms and up even further to larger organisms like birds. These larger organisms chew on organic matter to decrease their size, making them more available and accessible for microorganisms to decompose them further.
“Plants know how to take care of their needs. It’s just a matter of having the biological components in place for these interactions to happen.”Troy Hinke
How Can Plants Take Care of Themselves? (13:36)
Plants photosynthesize sunlight and release anywhere between 30 to 80% of the energy they produce through their roots as exudates, which are made of proteins, carbohydrates, and sugars, to feed soil microorganisms.
Plants are able to manage their own needs by releasing certain exudates into the soil to attract microorganisms that will bring the nutrients, micronutrients, and minerals that they need. Through the predator-prey relationship, these nutrients are released into the rhizosphere in a plant-available form to be readily taken up by the roots. Plants feed microorganisms and the microorganisms feed the plants through this symbiosis.
“It’s a matter of us as humans managing the soil and providing the soil with what it needs so that the plants and microorganisms can have the proper habitat for this [symbiotic] biochemical reaction to take place in the soil, negating the need for any synthetic chemicals to be used on the soil.”Troy Hinke
Getting Life Back into the Soil (15:13)
We have lost life in the soil due to conventional agriculture and land management practices that have had a drastic effect on life in the soil. The main components that have had a negative effect on beneficial soil life are compaction, tillage, and chemical use.
Compaction happens when heavy machinery are driven across fields. This compaction creates anaerobic dead zones where pathogenic fungi and bacteria that are harmful to plants begin to breed.
Tillage tears through the soil and rips through miles and miles of fungal hyphae, disrupting and killing populations of beneficial microorganisms. Reducing tillage practices and going no-till prevent this disruption of beneficial flora in the soil.
Chemicals reduce the population of beneficial microorganisms in the soil, and overuse sterilizes the soil. When herbicides and pesticides are sprayed onto the soil, these have an effect on more than just the intended insect or weed. They also kill the biology in the soil and more often than not, make plants chemically dependent.
Succession is moving from bare soil to weeds to grasses, all the way up to coniferous and deciduous forests. At the very beginning of soil succession with bare soil and weeds, the soil is bacterial dominant. In the middle stage of succession with row crops, tall grasses, shrubs, and bushes, the soil becomes equally bacterial and fungal dominant. Finally, as the land moves into deciduous and coniferous forests, the system then becomes fungal dominant.
Bacteria dominant soils are more alkaline because of the enzymes and exudates they release, while fungi-dominated soils are more acidic.
Setting Up the Land for More Weeds (24:30)
When we’re talking about bacteria dominant soil in succession, the plants that predominate the land are weeds, and plants that predominate fungi dominant soils are trees.
Looking at it logically, conventional agricultural practices like compaction, tillage, and chemicals are killing more of the fungi in the soil. And if the fungi in the soil are getting killed, that leaves the soil more bacteria dominant.
This means that when people are tilling and using herbicides to try and get rid of weeds, they’re actually setting themselves up to have more weeds. But if the biology in the soil is right, and there are more fungi in the soil than bacteria, the biology can do the work for us, and there would be no need for chemicals.
Important Takeaways (27:28)
Plants photosynthesize sunlight and turn it into carbon and energy. That energy is released through the roots as exudates, which attract bacteria and fungi. Bacteria and fungi decompose organic material and hold excess nutrients in their bodies, and when their predators come along to consume them, those excess nutrients are then released in forms readily available to plants.
Through compost and compost tea, we are creating these biological inoculants to get life back into the soils.