RESTORING SOIL BIOLOGY: THE JOHNSON-SU BIOREACTOR YIELDS KOMBUCHA FOR SOIL
“What we humans must always keep in mind as we go about making sure there is enough food to go around is that this body of material we call manure, or compost, is neither factory machine nor barren waste, but a lovely, intertwining jungle flock of living things to be fed and managed lovingly, much like we manage the other livestock on our farms. Our most important livestock, in fact, are invisible to the naked eye.” —Gene Logsdon BY JOEL JOHNSON
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f your hometown is anything like mine, it has been swept up in the recent kombucha craze. The simple fermented beverage, now on tap in corner stores, coffee houses and breweries, offers a number of benefits, the most widely touted of which is jumpstarting the gut microbiome by introducing beneficial bacteria. While kombucha’s rise may be in part a pop culture fad, it is also a response to the reality that the American stomach is in crisis. Studies like the Immigrant Microbiome Project have confirmed that individual gut microbiomes lose diversity almost immediately upon arrival in the United States. “[The] modern lifestyle in the U.S. may be causing each generation to lose more of their ancestral microbes… [and] The obvious explanation for all of these changes is diet,” University of Minnesota scientists Dan Knights and Pajau Vangay wrote for The Conversation. In short, a homogenized food system translates to a more homogenized gut microbiome, which may have negative effects on immune system strength and correlate to susceptibility to a myriad of diseases, including obesity. Amazingly, a nearly identical process has been occurring in the soil beneath our feet. The soil food web contains billions of bacteria, fungi, and microorganisms that process nutrients into plant available forms (among many other functions). But decades of plowing, synthetic fertilizer applications, and homogenized monoculture plantings have weakened the microbial community that ultimately sustains agriculture, resulting in compromised soil immunity and weakened crops. “It’s just like us,” Dr. David Johnson of New Mexico State University’s Institute for Sustainable Agriculture Research PG. 8 :: SPRING 2020
explained at the Soil Carbon Trading Roadshow, “If our stomach is out of order, we’re a mess. We’re not functional. We take this for granted much of the time, but when it’s out of order, we’re on our knees. And I think soils are not much different.” To restore the functionality of soil microbial communities, Johnson and a team of other collaborators, including his wife Hui-Chun Su, have been reimagining compost. It all started when David was tasked with determining a method of composting dairy manure that would decrease its salinity. While he employed traditional methods of windrow composting, day after day he came home in compost-stained clothing. Hui-Chun decided there must be a way to compost that achieved better results, and required less laundry. Together, they developed one. The Johnson-Su bioreactor is essentially a wire cylinder interspersed with piping, centered on a wood pallet base. The piping allows oxygen to penetrate every square inch of the compost—rather than only the top foot—without turning it at all. This makes the composting process aerobic (read: less smelly and more effective) without disturbing the fungal communities that populate the pile. Those fungi turn out to be key to the desalinizing. They excrete oxalic acid, which can bind to metal ions
like sodium, tying up salts and reducing the salinity—a must for dairy manures and desert soils. And all of this can be started with a half-day of labor and between $4085 of material. The next step, however, requires a little more patience. Letting the compost sit for a full year in the reactor results in a clay-like substance, demonstrating that the organic material has been broken into its most basic elements and the fungi and microbes are ready to reproduce. The resulting compost is like kombucha for the soil—a microbiological inoculant for crop fields, pastures, and gardens. Mixed with water, the compost can be used as a foliar crop spray, or a slurry of milk, molasses, and compost can be used to inoculate seeds. It also makes a rich compost for amending soil or using as a direct planting medium. Pat DeSimio, co-founder of Cruces Creatives makerspace and the MESA Project (Meetings for Sustainable Agriculture), has worked with Dr. Johnson since 2013. He has helped facilitate bioreactor workshops, as well as working on technical manual and training materials to accompany the bioreactor. “One of the really great things about the system is that it [yields] amazing results for soil health and plant health by cultivating the microbial communities, and it is relatively low-effort to implement,” DeSimio says. In trials of the compost as an inoculant, “I observed a doubling in crop productivity over the average yields in this county for both cotton and chile,” Dr. Johnson adds. Julie Shedko, of Lettuce Grow Farms and Educational Center in Taos, NM, attended a bioreactor building workshop with Dr. Johnson in 2017. The following Earth Day, she hosted a community workshop to build a reactor and place it in a greenhouse she managed. “We watered it one minute a day, and then we opened it
