The Dance of the Elements
Matt Drewno on How to Compost with the Carbon Cycle
by Torrey Douglass
If Matt Drewno could ask of you one thing, it would be to “Challenge yourself to grow your own soil as best as you can.” It’s easy to walk into a nursery, feed supply, or big box store’s garden center and walk out with a bag of high quality dirt, but Matt recommends against it. “People feel like they have to buy things to make it work, but that’s not necessary. You don’t need to spend $1,000 to grow a head of lettuce.”
Matt is the Vice President of Ecology Action, founder of Victory Gardens for Peace, and Director of Biointensive Community Garden Initiatives in Fort Bragg and The Stanford Inn Biointensive Research Garden in Mendocino—so he knows a thing or two about how to care for plants. Rather than buying soil, Matt encourages people to simply mimic how nature makes it. It’s arguably the best thing we can do for our food supply. As Matt puts it, we should “feed the soil, not the plant—a healthy soil will grow healthy plants.” To do so will deepen your relationship with nature as you connect with its cycles, harnessing the perpetual dance of our planet’s elements, a process both primordial and poetic.
The basis of all life on earth stems from the photosynthesis and respiration of plants—an ongoing reciprocation between a plant and the four elements. The sun (fire) provides warmth, air supplies CO2 and oxygen, earth offers its minerals, and water carries nourishment throughout the plant’s body, much like blood does within ours. The plant turns sunlight into sugar, and sugar into energy, then uses that energy to pull carbon (CO2) from the air and minerals from the soil to grow more of its plant body, while simultaneously breathing out the oxygen we humans are so fond of.
Matt describes topsoil as “where atmosphere meets earth,” continuing, “at that interface there’s a lot of transformation and dynamic processes that generate abundant, healthy soil that feeds the plants. [There are also] microbes and other organisms living in the soil, making paths and tunnels, and leaving their waste.” That waste adds nourishment while the tunnels allow air flow, an important benefit since the biological material can’t break down without it.
It takes 500 - 2,000 years to build an inch of topsoil naturally, and agriculture requires increased nutrient cycling, so it makes sense for humans to step in and help things along. Feeding the soil keeps land from becoming depleted, and when done correctly, that land can remain productive indefinitely. Matt points out that there are farms in Asia that have been producing food for over 4,000 years, yet in the United States, farmers often have to rely on inputs like chemical fertilizers to maintain productivity after just 40 years. And considering that we are headed toward a post-fossil fuel future where those toxic inputs may be less affordable and local food will be the default, maintaining rich, healthy soil to grow that food will be essential. Matt encourages, “You can grow your own soil—it’s cheap and easy and it’s one of the best things you can do now, and for the future.”
At the heart of growing soil is harnessing the carbon cycle— that dance between plants and the elements. Once moisture is removed, plants are roughly 50% carbon by dry weight, so the goal of composting is to create carbon-rich soil that can become future plant life. Carbon farming involves growing plants not just for the food they produce, but also for their biomass—the unused parts of the plants left over after harvest. Selecting crops that generate high volumes of biomass in addition to their edible output will increase the carbon removed from the atmosphere during their lifespan and give a gardener lots of raw material for soil building after it. Organic gardening pioneer Alan Chadwick was fond of saying “Life into death into life,” describing how plants grow, then die, then feed new life. This is the dance soil-building gardeners step into, learning the steps and feeling out the rhythms. And with an expert like Matt at the lead, you will be finding your groove in no time.
The key, according to Matt, is the balance between mature and immature plant material. In the past, composting advice has categorized the types of materials to add to your compost as brown/green, wet/dry, or carbon/nitrogen. A better approach is the mature/immature description. Immature materials come from plants before they’ve flowered, transitioning into mature materials once that process begins. Explains Matt, “once they begin flowering, their carbon structures transform, becoming more rigid to support the plant getting off the ground and into the air, resisting the wind and ultimately flowering and bearing the weight of seeds.” To find out if a part of a plant is mature or immature, test its rigidity—if it snaps when you break it, it is mature.
Matt continues, “Immature materials are soft and flimsy, and have simpler carbon structures which break down quickly. They help drive a more intense decomposition process with a greater degree of sugars and starches.” Examples can include garden cuttings, fresh cut grass, cut fresh flowers (provided they are organic and not treated with preservatives), cooked food waste, livestock manure, and pruned plants provided the stems and leaves are fresh green and pliable.
In contrast, “Mature materials break down slower, often require a diversity of microbes and host a small ecosystem to break down completely. This slows down the carbon cycle.” These materials can include dried leaves, sticks, and branches from cleared land, corn cobs, rigid vegetable cuttings like a broccoli stalk, and raw potatoes, celery, or carrots.If it takes some effort to chew, you can consider it a mature material.
The balance between the two types of materials is essential to quality compost. Says Matt, “Compost derived from immature materials tends to be rapidly utilized and doesn’t persist as long in the soil. Compost derived from mature materials tends to break down slower, cooler, and is less rapidly available and more persistent in the soil. Having a mix of both helps generate organic matter (compost) which is both available in the short and long term throughout the year.”
Matt continues, “The carbon cycle is CO2 from atmosphere absorbed into plants as carbon, then broken down by microbes and transformed into organic matter. Organic matter is largely carbon-based organic materials undergoing various stages of decomposition, dead microbial bodies, living microbes, carbon chains, and complexes—all of which have a spongy character that can hold moisture, nutrients, life, and fertility.”
A home compost pile should be a minimum of 36” high, wide, and long. If it’s in a container, creating a frame with walls of hardware cloth or old fencing is ideal since it will allow air in while keeping critters out. Start with a 3” bed of dry sticks. This will keep the rest of the pile off the ground and will also aid air flow. Follow that with 3” of mature material, 3” of immature material, and a sprinkling of soil followed by water. Continue to add alternate pairs of layers of the two materials along with the intervening soil sprinkling until the pile is 36” high.
It’s important to “build the pile with as many different materials as you can, and no more than one third of any one material,” according to Matt. “Keep the pile straight and vertical—not tapering, not leaning—build it as if you were building the foundation of a house, nice and sturdy.”
Turning the pile will speed decomposition but will also release carbon into the air, thus removing it from your future soil. For a more carbon-rich compost, resist the urge to turn over your pile and just let it be, occasionally adding water to keep conditions moist. Matt calls this “cold composting,” describing how the process “heats up at first, but has a slow cooling off period without the drastic booms and busts in microbial populations produced by turning. This slow cool off curve represents a dynamic and complex ecological succession, resulting in a richer and more complex end product. Think a good cave-aged wine or cheese that are set in the right direction and minimally interfered with, vs. pasteurized products which lack the complexity and character which defines quality in nature.” And if you build that pile on a vegetable bed, once the resulting compost has been removed to feed other areas, any fertility that has leached from the pile into the soil will benefit whatever you choose to plant there. Matt recommends potatoes or sunflowers as excellent options for a post-compost-pile garden bed.
Ultimately, Matt advises that you think of your compost pile as “an organ of digestion for microbes to transform once living organisms from death into the raw materials for life again. The more diversity of materials in the pile, the more diversity of life breaking down those things, the more diverse and complex the compost end-product.”
When your soil is rich with complex organic matter, it has a robustness and resilience it will transfer to the plants it feeds. Matt reflects, “Many important antibiotics and other medicines come from microbes which inhabit compost piles, like penicillin! Quality compost is like a “farmacy” for the soil and helps plants resist disease and pest outbreaks, while promoting good health and balanced nutrition.”
Adapting to whatever the future holds will require looking at things with a fresh perspective. The ingredients for a thriving compost pile are materials often seen as waste, yet with a revised outlook and a willingness to learn the rhythms of the carbon cycle, that waste can be transformed into biologically rich organic matter, pulling life from death and preserving the valuable topsoil that we rely on for our food.
Register for Matt’s fall Sustainable Agriculture Course at the Mendocino College Coast
Campus at www.mendocino.edu.
To find out more about composting, Matt recommends:
growbiointensive.org/PDF/FarmersHandbook.pdf (pgs. 3-6)
Victory Gardens for Peace is a project of Ecology Action. They offer a free seedbank with 1500+ varieties, affordable soil testing and analysis, free sustainable gardening resources and growing guides, internships, apprenticeships, and classes covering sustainable agriculture. www.victorygardensforpeace.com (Passcode for the seed bank: saveseeds!)