Anyone who’s gone on a walk across the farm and made a couple wrong turns by the storage barn can tell you, the compost pile is no place for a picnic. Even before you catch sight of the pile you might catch a whiff of excess nitrogen evaporating into ammonia, bacteria producing any number of volatile organic chemicals as they break down complex sugars and cellulose, anaerobic respiration rotting away veggies and hay deep within the pile, or the musky, earthy smell of humus, the final and least odorous stage of composting. Even if the smells don’t bother you, the temperature might. Microbes produce heat as a by-product of respiration raising compost to such high temperatures that large piles can spontaneously combust! A well-managed pile can be transformed, with a little human ingenuity, into a heating device for water, houses, or greenhouses.
Although we might not want to eat a meal beside one, a compost pile is a critical step in producing organic lunches. A compost pile promises, with the help of microorganisms and management, to recycle nutrients from dead organic matter back into the soil and give rise to a new crop of veggies. Like a phoenix from the ashes, the lettuce piled high in compost bins this year will rise again! This closed loop system is emblematic of methods of sustainable farming which seek to not only add nutrients to the soil but to find ways of making those nutrients stick around year after year. Although all soils lose nutrients to the water and the air, soils that are densely packed with microbial and vegetative life are more resistant to nutrient leaching simply because more nutrients are ‘in-use’ at any given time.
Most of us only know of compost as a soil amendment but it has many other uses. Newly excavated land can be spread with a ‘compost blanket’ to prevent erosion, for example, due to compost’s large water-holding capacity and its ability to attract plant life. Even the process of creating compost has a useful by-product in heat. Jesica Clark, an urban farmer working in Kingston, New York, has devised a beautifully simple compost-heated greenhouse fueled by urban compost; coffee grinds and yard waste. The greenhouse has layered bays with compost on the bottom, a layer of newspaper topped with mulch as a barrier, and potting soil on top. When the compost starts to cool down, indicating the completion of the composting process, Jesica simply harvests the veggies on top and then the compost underneath to spread on fields. Here are her veggies in full bloom in the bitter cold of a New England December…
And so, with a lot of hard work and impeccable timing, we can get even more out of compost than we put in. As is the case with the mythological pheonix, composting resurrects what went in to in (i.e. nutrients) and provides a significant amount of heat energy. It may take a lot of investment and infrastructure, but harnessing compost-power seems like a promising, almost magical way to recycle nutrients and energy.