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Turning the Pile : Part II of a New Year's Tradition


Sarah E. Photography

After finishing our field peas and greens to bring the fortune of coins and paper monies in the new year, it’s time to turn - those compost piles! Thinking of the year in retrospect I like to look at how I / we have transformed obstacles into opportunities. It takes work, but with dedication and maintenance, we

succeed and grow, learn and heal from the opportunity.

Similarly, the idea of viewing something as ‘waste’ has the potential to be transformed into viewing that same thing as “merely a resource misused”. Our food scraps, garden waste and animal droppings may seem like a smelly, burdensome and potentially harmful waste, but when cared for, these burdens transform into the nourishment that keeps our garden growing, microbial community rich and it holds onto that precious water resource so essential to all life.

Waste is but a resource misused

Composting is not hard. We hope to one day scale up to some beautiful sizable wind rows once we have a skid steer or bucket tractor in our tool barn, but for now we turn with shovels. We go slowly, steadily and purposefully, with the warm heat in our hearts and gentle beads of sweat reminding us that it takes effort to transform something.

Compost is the systematic thermal decomposition of organic matter. The systematic part implies that it requires effort, order and discipline to maintain the complex process of microbial succession and pathogen-reducing thermophilic (heat-loving) decomposition. The beginning stage of setting up the right recipe takes the most effort. A thick layer of wood chips and wood slag, then a layer of organic material, then a cap of more woody material.

A 3:1 ratio of wood waste to food and poo scraps (by bulk volume) generally does the trick. We then grab that spade, shovel or pitch fork and mix it into a nice conical pile. The bulky wood chips on the bottom allow air to enter the pile, where the oxygen feeds the indigenous organic acid-producing bacteria like lactobacillus and acetobacter that kick the process into motion. Respiration from these tiny microbes begins to generate warmth and an upward draft, that makes the pile act like a chimney. Drawing air in from the bottom as the warming air rises and pushes out the top of the pile. This in turn creates the perpetual draft that keeps the air cycle in motion, supplying O2 to the microbes, lowering the pH of the environment and driving off excess moisture. This first phase of the microbial succession is referred to as the mesophilic – or “medium heat-loving” phase. Over the next 15 days material can be added and mixed similarly, mixing at least 5 times thoroughly. Temperatures will rise over 100F as the pile and microbial

community transform!

After the initial 15 days, we transfer the pile into the next bay. More shoveling, more sweating! I keep telling myself this is how you make 40 years of age look good! In this middle compost bay we stop adding new material, but we continue the process of mixing 5 times over 15 days and maintain our chimney structure. Watch, and the temps will quickly shoot up to 130-180F as the second phase of microbial succession takes over, entering the thermophilic phase as the substrate is transformed, and new

players enter and proliferate in this journey of digestion and transformation.

Particularly, there is a rise in population of gram + bacteria, such as Bacillales and Symbiobacterium, that munch up the digestate transformed by the mesophilic bacteria. Keeping the process aerobic, with plenty of air flow, as well as keeping it moist, is key to this essential function of this phase, pathogen reduction (chimney piles have a tendency to dry out in this phase, as microbial activity accelerates and drives off moisture).

Maintaining this pile at 130F or above for 15 days has been proven to reduce and even eliminate harmful pathogenic bacteria like E. coli and Clostridium, as well as destroying germination potential for unwanted seeds in the compost that could later sprout in the finished compost and wreak havoc in your neatly groomed garden beds. No need to add any heat in this phase; the heat generated by the rapid growth and respiration of the microbial cells does all the work for you!

As we surpass day 30 in this compost journey we once again dawn our shovel or pitch fork and flip the pile, this time into the final curing bay. The “cure” is the final stage of microbial succession, where heavy lifting is transferred from the fast munching bacteria to a host of new players that clean up the scraps and reduce the overall microbial activity, leading to the temperature cooling of the piles. This team of “finishers” is from everyone’s favorite kingdom: FUNGI!

Fungi are present throughout the entire process from beginning (mainly cellulose degrading yeasts) to end (where white rot mycelial fungi thrive), but they really thrive here. Using their arsenal of acids and enzymes, they can breakdown complex lignin and cellulose structures into smaller digestible substrates that the bacteria can consume. Eventually, over 30 to 90 days, the substrates are consumed, the munching slows and the pile stabilizes at an ambient temperature.

To check for a finished cure, we mix up the pile and check the temperature the next day. If the pile has heated up, that implies there’s still work to do for team microbe. It is important to have a complete cure so that the process of heating and acidification does not continue in your garden when you spread your compost. These characteristics can lead to poor germination of seeds, and can even kill transplants. A key indicator to cured or nearly cured compost is the visual inspection of a white ash dusted through the pile. This is the product of a fascinating bacteria, actinomycetes, a gram positive aerobic bacteria with antimicrobial properties, that grows in mycelial patterns (like a fungus!). The ashy trails are remnants of indigestible salts like alkaline earth metals, along the pathways where the filamentous mycelial structures of this bacteria were present. If you think it looks like ash, you aren’t too far off. Chemically, this metabolic product is similar in structure to ash!

So, why does finished compost never get sick? Because it’s already been cured!

As we stand back and reflect on how we've transformed waste into a nurturing addition to our garden, we plan to apply the same effort, discipline, and patience to our own lives in the coming year, knowing that it will give rise to many new cycles of growth and enjoyment. Thank you to all the visitors, human, animal and microbial, to our home, farm and brewery, that sustain this cycle of transformation. As we like to often relish with our friend Ellen Kochansky, founder of the Rensing Center for the Arts, compost is metaphor for so much of life. I invite you to take the time to consider what lessons compost has to offer you.


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