Compost: The Most Important Organic Soil Amendment
J.I. Rodale, an organic farming pioneer and founder of the Rodale Institute, in the Encyclopedia of Organic Gardening wrote, “In the soft warm bosom of a decaying compost heap, a transformation from life to death and back again is taking place. Life is leaving the living plant of yesterday, but in their death these leaves and stalks pass on their vitality to the coming generation of future seasons.”
The process of composting is a form of biomimicry. Nature ultimately and systematically breaks down and decomposes all life’s substances transforming them into a resource for new growth. Composting creates ideal conditions to speed up that process and produce a high-quality input for soil and plant health in the farm and garden.
John Wick of the Carbon Farming Project – which demonstrated the role that compost plays in sequestering carbon in the soil – says, “When making compost, if you create the ideal conditions, naturally occurring bacteria populate that pile. They’re already there. They start building their bodies out of those ingredients and through their respiration, it gets warmer and warmer and warmer. Then only thermophilic bacteria can tolerate the high heats and in that environment, weed seeds and pathogens are destroyed.
“When you make thermophilic bacteria-based compost, you create a beautiful molecule, a little carbon-nitrogen molecule covered with life, and it turns out when you put that compost on top of the soil system, the soil knows exactly what to do with it.”
Compost made from leaves, grass clippings, kitchen waste, manure, weeds, twigs, agricultural waste, etc. supports soil fertility, creates a good environment for beneficial soil microbes, suppresses plant disease and can be good for the climate. According to Dr. Whendee Silver of UC Berkeley, “Composting manure actually decreases greenhouse gas emissions. We’re measuring greenhouse gas emissions from the composting process; it appears that composting, if you do it well, leads to relatively low emissions compared to allowing the material to naturally decompose, which can lead to carbon dioxide, methane and nitrous oxide emissions.
“If you put the material into a well-managed compost pile and keep that compost pile turned – weekly turning is sufficient – that results in relatively low methane emissions and very low, undetectable emissions from nitrous oxide [a greenhouse gas more potent that carbon dioxide and methane].”
The Multiple Methods of Composting
The multiple soil health benefits of compost have been known since ancient times. Today commercially produced compost is available by the bag or by the truck load, but can vary greatly in quality depending how the compost was made and what materials were used. Were they exposed to noxious inputs that have not properly degraded like antibiotics in chicken manure or herbicides in green waste? Those things are difficult to know. However, with some trial and error, it is relatively simple, whether you are a gardener or a farmer, to make your own. There are several different methods of composting so the process can be adapted to different scales, uses and preferences. All methods, when done properly have similar benefits with some notable differences.
Thermophilic composting, which can be done on a small or large scale, is an aerobic process in which microorganisms consume carbon and generate heat that can kill weed seeds. Vermicomposting, usually done at a small scale in a bin, uses red worms that eat kitchen scraps and plant residues, produces nutrient and microbial rich castings that have similar benefits to thermophilic compost, but doesn’t kill weed seeds. Vermicompost, unlike thermophilic compost, has naturally occurring plant growth hormones. Depending on how the compost will be used and applied, the two methods have their pros and cons.
Compost Tea, researched and popularized by Dr. Elaine Ingham of the Soil Food Web Inc., is a process in which quality compost is brewed into a tea that greatly increases the beneficial microbial population so that relatively small amounts of the tea can be sprayed on large acreage to increase soil biology and fertility. Sheet composting, popularized by permaculturists, is a low labor method that is done in place in the garden bed. In this brief podcast, ecological farmer Bob Cannard explains how to do sheet composting. Biodynamic (BD) compost has specially made BD preps and herbs embedded in it that attract cosmic forces into the compost pile that help harmonize the life force and energies of the farm. The latest breakthrough on compost has been made by Dr. David Johnson, of New Mexico State University and CSU Chico State, who has developed a unique composting process that results in a fungal-dominated compost that his research has shown to increase crop yields and dramatically increase soil carbon sequestration.
Compost is the single most important amendment for organic regenerative gardeners and farmers. It increases the health of the soil, which promotes healthy plant growth. Composting is an ideal way to turn food waste into a valuable resource and composting animal manure and other waste reduces greenhouse gas emissions. And as a tool to mitigate climate change, compost increases the soil’s capacity to sequester carbon from the atmosphere.