Look Closely At Compost

Nathan Rutz is our Director of Soil, and he's brimming with know-how when it comes to questions like, how is compost made? He's intimately aware of what goes into the making of organic growing mediums, because he's studied the masters like Karl Hammer of Vermont Soil and he works at his craft daily. 

In this season of renewal, Nathan appreciates the mysteries like microorganisms that seem to magically appear in a compost pile even as it reaches 131 degrees Fahrenheit. He explains how colonies of bacteria and fungi tuck in to a feast of food waste. Armed only with the reactive qualities of air, moisture, heat (and some elbow grease to turn the pile) and time, it becomes compost.  Compost that gets worked into a "soilless mix" (he can explain that, too). In the case of Tilth's Grow, our bedding mix, it is a living soil blend.

He starts with a definition - Compost is not soil. Soil is sand, silt, clay and organic matter (which may contain finished compost). If you dig a field or backyard, you'll find soil in layers. Layers that scientists have identified based on their composition. The "O" layer is at the top and is where leaf litter and decomposers like earthworms meet. Next is the "A" layer of mineral and organic matter. Then, the layer of weathered parent material and, finally, bedrock. 

In a forest, the feast and resulting compost happens in situ or where the leaves fall.  Us mere mortals rely on a process of mixing materials like nitrogen-rich food waste and carbon-rich leaves and wood chips together. 

"We are creating the conditions for an explosion of microbial life, and that explosion does the decomposition," Nathan explains. "I’m a Christian, I believe in impossible things, so for me, one of the great mysteries of life (is) we have thermophilic bacteria floating around. They thrive above 131 F and multiply enough once they get to that temperature. What are they doing most of the time?”



Assembling the nitrogen and carbon in the correct ratio and turning the compost pile five times when it reaches 131 F kills weed seeds and pathogens like eColi (and it’s what makes  our products National Organic Program-compliant). During that time, microbes are eating, discarding nutrient-rich waste (all those apple cores, banana peels and coffee grounds contains nutrients like potassium which is needed for healthy plant growth) and eventually expire to form a "necromass."

“At the end of the process, the stuff is made delicious through the corpses of microbes (necromass).”

“The fact that this process can be done anywhere on the planet with any trash around and the result is clean and safe and it’s free strikes me as providential”.

That is just the beginning of compost. After cooling, fungi set up shop and eat the lignin or woody parts of the compost pile. 

Compost helps the planet because it avoids the release of methane, a potent greenhouse gas, into the atmosphere, which is what happens in landfills. The other benefit to compost is to improve the photosynthetic capacity of plants. Healthy soil comes from plants providing more nutrients and attracting microbial partners. 

We make potting soils -- technically it's soilless medium (remember, soil is a sand, silt and clay mix). Grow is compost mixed with organic material like peat moss. We acknowledge that peat moss harvested from Canada and trucked 1,128 miles to Cleveland is not sustainable, even if only 0.03% of Canada's peat lands are harvested. (Neither are the other options: mono-cropped pine bark or coconut coir from clear cuts in Southeast Asia). There's no other way around building the ideal growing media; ideal because it achieves the perfect pH balance that seedlings need to grow. No other way until the day that soil scientists like Dr. John Biernbaum, a horticulture professor at Michigan State University, succeeds in figuring out how to make compost a complete growing medium. 

The addition of peat to the living microbial community in compost is a boon for plants. The nutrients are available and are taken up through the roots into the structure of the plant and soil plays an important part in this exchange. 

"You want holes and pores and solids because you’re striving to have air filled and water filled pores. Roots are mostly aerobic. If you think about a nice soil, it’s like chocolate cakey."

It should also smell nice and woodsy, like that favorite forest of yours.

* * * *

Bed prep season is upon us, and some of the tree trimmings we typically find in cleaning up our yards can be used to build up new beds. Sticks and leaves piled into a bed bordered by larger branches or trees that have fallen over the winter are free, natural, raised bed (or hugelkultur as they say in German) material. Form the borders of your bed with the logs and big branches and pile the yard waste in --  sticks on bottom and leaves on top. Pile it high because when it's settled a bit from the rain and your boots, it will be ready for a top off of bedding mix. 

Interested in learning more? Stay tuned for our raised bed workshop in partnership with Michael Bartunik at Ohio City Farm later this month.

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