A Novel Approach to Farm Waste Management

Originally published in the Winter 2000/2001 issue of Mushroom, The Journal

The news from the heartland is not good. Manure ponds bursting with fecal-rich effluent leach dangerously into the watersheds. River ecosystems are imperiled. Pfisteria, E. Coli, amoebic parasites and viruses are posing ever-increasing threats to our health as corporate farms place profit and production at the expense of environmental health.

As a nation we face a biological time bomb in yet another example that fact can be stranger than fiction. The successful practices of small farms are not replicable for industrial factory-farms which crowd ever-increasing populations of livestock—hogs, cattle, and chickens in particular—into tighter quarters for ease of feeding and slaughtering. The enormous consequence of the waste by-products stresses the health of human and environment alike.

Many believe we have exceeded the critical mass of what our habitats can absorb. Our waste streams literally runneth over, into the waterways of our nation, wreaking havoc which can be felt on every level of society. Scientists have publicly speculated on the ultimate consequence of such practices, but only cataclysms draw the public's immediate attention. Soon, for most citizens, an atmosphere of "all is well" prevails in absence of blatant, disastrous evidence to the contrary. We exist perilously close to the edge. The menace of manure overflows can spread diseases not yet known. As one friend ruefully warned me, we must be more careful, since "Nature bats last, and the bases are loaded".

As populations encroach upon once rural lands, the threat of biological disasters from untreated farm wastes represents a virulent threat to our personal and national well being. Corporate giants play political football, demonizing opponents, especially anyone supporting government regulations, pitting farmers against environmentalists. The game of who controls our biological future takes on a surreal atmosphere of a bad science fiction novel. Proposed solutions have been few and far between. In absence of a remedy, the theater of conflict features a growing cultural divide. Is there a solution? I think so. The opportunity lies, literally, underfoot.

Hog farms are particularly worrisome to environmental scientists for the enormous problems they cause. Recently, when hurricanes hit North Carolina with a vengeance, the monsoon rains caused dikes to burst, flooding thousands of acres with animal feces and causing incalculable health problems for both farm and non-farm residents. Residents in Charlotte, many of whom thought they were well removed from the threat of manure ponds, were rudely awakened to the enormity of the problem when it covered their doorsteps. Filth filled the streets, flooding basements. The collateral damage is still being calculated—the fouling of wells, the loss of fisheries, crops, livestock, the spread of diseases including mysterious illnesses, and not the least was a growing erosion of public confidence in farmers as good neighbors, etc.

The best of ideas are those which are self-evident. Our extended family (my cousin) farms wheat and barley in Eastern Washington on a several thousand-acre farm. First settled by my great grandfather, the Davis farm in the Palouse country is renowned for its thick and rich topsoil, a gift from the unrelenting winds over thousands of years that stripped eastern Oregon of its surface sediment and deposited its riches to the north. Once more than 100 feet deep, farming practices have steadily depleted the soil bank to a mere fraction of its original state in only a hundred years. Understandably, fertilizers have become increasingly important for sustaining crop yield. Several years ago, my cousin Jim Davis of St. John, Washington, adopted the no-till method of farming, much to the skepticism of neighbors. On a recent visit in October, he pointed to the family wheat fields adjacent to a neighbor who continued the practices of his predecessors. Our farmlands were rolling hills of chopped stubble that had been left for Nature to recycle—whereas the neighbor's fields were furrowed with deep grooves from erosion. The contrast in the loss of topsoil was dramatic, and a clear lesson to even the most uneducated.

The no-till method succeeds largely due to an unseen ally—beneficial fungal mycelia. Researchers at Montana State University have discovered that the resident mycoflora, particularly the "higher" fungi (sexual fungi which produce a fleshy reproductive structure, i.e. a mushroom) aggressively decomposes the stubble in no-till farms. These nearly invisible saprophytic allies extend their fine filaments of fungal cells, separating plant fibers, and through their enzymatic systems, break down plant cells into basic nutrients. The need for fertilizers is reduced. Soil is created. Soil structure improves. Erosion is minimized as water is slowed and absorbed into the sponge-like mycelial networks. The end result is a crop less demanding for external subsidies. The no-till method is the first major step agriculture has adopted on the road to greater sustainability. What I propose is the next logical step.

As the mycelium decomposes the crop stubble, an extensive network of fine cells is projected. This cellular network is literally a food web for the fungus. Not only is the mycelial network exquisitely efficient in recycling plant debris, but it is also efficient in another surprising arena. The mycelium can gobble up bacteria and sequester nitrogen, slowing the passage of water (and effluent), and in doing so becomes a biological filter. I call the use of mycelium in this fashionmycofiltration. The beauty of this method is that it is Nature-designed and proven in the laboratory of life. How to maximize the beneficial properties of mycelia is the challenge we face. The technological expertise, however, is surprisingly simple and readily adaptable to current farm practices.

Farms are generally well equipped for rapidly adopting the fungal solution to pollution, especially those using an abundance of wood chips and straw, and those growing cereal grains, such as wheat and corn. Corncobs are perfectly structured for hosting mushroom mycelia, with a combination of fiber and microcavities allowing aeration and food for rapid colonization. Mushroom mycelium is highly adaptive, and is far easier to grow than actual mushrooms.

Example of a mycofiltered manure holding pond

Gently sloped land below a feeding lot or manure pond is an ideal site for locating a mycofilter. The key is the continual seepage of effluent from the pond into an above-ground constructed organic "drainfield". What this means is that a crude mixture of waste straw, sawdust and/or wood chips, and a wide assortment of farm wastes are loosely scattered on the ground to a depth of 12 inches, in layers. In fact, you are creating a shallow compost pile. The first layer should be sawdust or wood chips spread to a depth of 3-4 inches. The next layer, about 4 inches deep, containing corncobs and sawdust mushroom spawn, is applied on top. The spawn can be applied by hand, or by using a silage spreader. Spawn is applied at the rate of .25 lbs to .5 lbs per square foot. The final layer is loose straw laid to a depth of 4-6 inches. The straw layer provides shade, aeration, and allows moisture to flow to the central layer. The surface area of the mycofilter should be at least equal to several times the surface area of the manure pond/field, depending upon depths, slope and flows. Each mycofilter has to be customized to every location.

If living in an area of high wind, where evaporation is a problem, placing waste cardboard over the top, but underneath the straw, will greatly aid the underlying mushroom mycelia. Once built, preferably in the spring, sprinklers are set up for the first two weeks until the system becomes charged with mycelia. Once established, the mycofilter will mature in a few months, and can become resident for years, provided that organic debris is periodically added to the top layer, and then recovered with straw. Red worms quickly proliferate and transform the mycelium, cardboard and residue into rich soil. On a two year cycle, the newly emerging earth berm can be broken down using a front loader-tractor, scooped up, and used as soil. The exact cycle will depend upon many factors, as the farm manager goes up the learning curve. Incidentally, gourmet mushrooms will form coinciding with spring, summer and fall rains. These mushrooms "re-seed" the beds, provided there is enough food for them to digest. For more information on project mycelium into outdoor settings, please refer to my book, Growing Gourmet & Medicinal Mushrooms, Ten Speed Press.

This idea came to me when, after moving to a waterfront farm on Skookum Inlet, Washington State, I installed outdoor mushroom beds in two gently sloping sections of my property which eventually became ravines leading to the beach where my neighbor commercially grows shellfish. I had inherited a small herd of 6 Black Angus cows, and a program to monitor upland sources of fecal coliform found my property was a source of pollution. One year after installing beds of mushroom mycelium, out-flowing water quality dramatically improved, gaining the attention of local officials. A series of further studies ensued, which later got the attention of researchers at the Battelle Marine Science Laboratories in Sequim, Washington. To make a long story short, we have applied for a patent for the destruction of targeted pollutants—both chemical and biological—but essentially the concept is the same.

I encourage farmers to try this method. The amount of time for installation a "mycoberm" is minimal, taking a day in most cases. The cost of spawn is probably the biggest expense, but once established and cared for, the mycelium can re-generate itself until the debris base has been reduced to soil. As the berms mature, they usually become covered with native grasses, which also have bioremediative properties. A universe of compatible organisms matures in this habitat, with mushroom mycelium being the keystone organism, opening the door to biological complexity, and ecological fortitude. I have a sense of personal pride in having come up with this idea, as I come from a family of farmers and scientists, conservatives and liberals. The mushroom mycelium is both an ideological and practical bridge between two extremes, harmonizing the activities of humans with nature.