reprinted with permission from Mycorrhizal Planet
Compost is not “any ol’ heap of organic matter” when you have biological perspective.
Bacterial compost results from a thermal process featuring a higher nitrogen charge and several turnings of the pile to aerate the microbe scene. Both of these actions rouse bacteria into action. The thermophilic phase in particular gets the pile cooking, thereby cleaning house of potential pathogens and weed seeds. The whole process generally takes six to ten weeks from start to finish. Commercial compost operations make this sort of “garden compost” for certified organic growers (adhering to federal restrictions) and home gardeners purchasing compost by the bag.
The carbon-to-nitrogen ratio of the materials to be composted expresses how nitrogen stands in relation to carbon content. Keeping the C:N ratio closer to 25:1 promotes rapid decomposition. A simple recipe for bacterial compost involves alternating layers of green (nitrogen-rich) and brown (carbon-rich) materials in equal proportion. Adding a charge of fresh manure from livestock or poultry to these piles ensures the proper nitrogen fix. Turning the pile weekly—as many as five times—allows bacteria to stay the course in all that biomass. Bacterial compost is just the ticket to help annual vegetables and flowers thrive.
Every compost pile of mine brings in a fungal element from the get-go. This “partial static approach” to thermal composting involves but one round of turning, and several months down the road at that. I steer the same course to start, layering nitrogen sources with carbon sources, and include dustings of kelp meal and Azomite for minerals. The inner core of a diligently made static pile heats up, while the outer edges take on a fungal imperative. Leaf litter from the forest floor brings a diverse fungal prospectus, in addition to making nice wadding to fill in against the stacked logs that enclose each pile. Fatty acid sprays (made whenever passing by to use the sprays on orchard runs) add a lipid boost for the decomposers working the periphery.
I typically start a new pile every spring, another by midsummer, and at least one fall pile that will carry through the winter months. The fixings come as we do garden work, mow grass, put up produce, rake leaves, press cider (thus creating pomace), and muck out animal bedding. Four to six months later comes reckoning time. This somewhat immature compost can be moved in one of two directions after taking away the stacked logs to provide access. Compost for garden use most often gets piled close to where a cover crop rotation is on deck or where garlic will be going in late fall. Bucket loading by tractor provides a rough-and-tumble mixing of the works. Give these field piles a few weeks to settle and cure. The resulting organism-rich compost is ready at that point to spread across field stubble.
Compost destined for orchard use faces another leg on its journey to application. Orchard piles consist of one part “rough-and-tumble compost” mixed throughout with one part ramial chipped wood, thereby upping the carbon-to-nitrogen ratio to more like 40:1. This is fungal sweet spot territory. Black gold. Texas tea. This woodsier pile will require another four to six months to come into its own . . . as the spot-on fungal compost craved by fruit trees and berries alike.
A few important distinctions should be made about what’s taking place at this juncture on the biological timeline. Fungi thrive on nondisturbance. Orchard compost will not be turned going forward in order to allow white mycelia to develop and spread throughout the bulked-up pile. That partial static variation on thermal composting makes possible a wider diversity of beneficial fungi than might otherwise occur. The ramial chipped wood helps create air passages that provide even more oxygen for those aerobic fungi to flourish. Soluble lignins in hardwood chips will begin the journey toward humification, ultimately forming macroaggregates. Conversely, using somewhat-aged softwood chips to create an orchard pile puts white rots at the helm in reclaiming more carbon than not. All organic matter has value in some form or another.
The passage of time is what’s key. Protozoa and nematodes reactivate during this maturation period. Microarthropods increase in number. In fact, once the pile has cooled down, diversity actually will continue to improve for the next six months. Orchard piles made in spring have additional potential if positioned along the forest edge. Tree roots reaching into the pile will leave behind mycorrhizal hyphae and spores by the time of late fall application.
Why fall? Compost applied toward the end of leaf abscission (detachment) furthers two orchard aims. The fall root flush continues to be at full bore—along with mycorrhizal outreach—and thus it is perfect timing for bioavailable nutrients from fungal compost to hit the ground running. Enhancing leaf decomposition ties in here as well. Compost anchoring down the fungal duff zone as the trees head into winter introduces yet more diversity. And should winter come early, take heart. Spreading fungal compost in the orchard and around berry plantings in early spring has virtue, too.