🗑️ Composting: Turning Trash into Treasure
Policy: Composting is an ancient practice, mentioned twice in Cato’s On Agriculture, that has been used for millennia in different forms to turn organic waste materials into rich fertilizer. Project Drawdown estimates that composting can reduce the CO2 equivalent of 2.14-3.13 gigatons between 2020-2050 simply by diverting compostable materials from landfills, which does not include the carbon that can be sequestered from applying compost to the soil. On top of these environmental benefits, composting can improve crop yields when applied in appropriate circumstances. The dual win on waste reduction and soil health presents the opportunity for a systems-level panacea, but the immediate incentives to individual actors remain murky.
At its core, composting mixes greens - materials rich in nitrogen - with browns - materials rich in carbon - and wets them in a confined environment for at least roughly two months until they are broken down into humus by bacteria, fungi, and, at times, worms and black soldier flies. This process, especially at an industrial scale, is closely monitored and balanced to ensure a strict carbon:nitrogen balance, oxygenation, and controlled decomposition process. Animal waste is an effective compost, especially in on-farm systems, while “Night Soil” (human excreta) has long been historically used as an organic fertilizer in different systems - though composting toilets provide a new twist. In particular, as Josh Tickell notes in Kiss the Ground, cow manure on soil is much more available compared to city-derived compost (2.4 million tons a day v. 106,000 tons, respectively) and methanotrophic bacteria in a healthy soil system that takes apart methane in said manure.
Various environmental benefits for composting exist, especially for farm-quality compost:
Water: Compost can act as a natural “sponge” for water, retaining up to 5-20x its mass in water, leading to erosion prevention, soil purification, and nutrient runoff prevention. This increases farm and ranch resiliency to extreme weather events. Compost can filter urban stormwater pollutants by 60-95% too.
Soil Carbon: various studies - most notably a 19-year UC Davis study - point towards the carbon sequestration potential of compost in regenerative agriculture. This study, which showed an increase of soil organic carbon of 0.7% yearly (the U.N. 's moonshot goal is 0.4% for context) also stored carbon in the more permanent soil layers between one and two meters deep. This also extends to the application of compost on grasslands.
Reduced stress on waste system: As the United States landfill capacity shortage grows, composting provides an alternative and productive flow for food and other organic waste (46% of the solid waste produced globally is organic or biodegradable - in line with USA EPA data). As of 2018, the EPA estimates only 4.1% of all food waste was composted while 56% was landfilled, and food is the largest single component inside US landfills, making up 24.1% of municipal solid waste. Landfill gas also represents 15% of enteric methane emissions in the United States. Composting presents the last-ditch attempt before placing organic waste in landfills.
However, composting presents several logistical and financial challenges as to why it has not effectively scaled in the United States beyond a 38% composting rate. For starters, the investment does not guarantee a favorable return, as it costs more to operate than landfills over time and 87% of all composting operations in the US did not survive after five years without government subsidies as of 2012. In addition, it can be a risky investment for a farmer as a soil amendment given specific yield predictions and the sheer amount of compost needed, which is between five to 20 tons of compost per acre according to the USDA. Complex composting systems also require expertise, be it in order to avoid spontaneous combustion or pathogens in compost, and careful political navigation of NIMBYism regarding smell, space, and unsavory wildlife.
In the US, we waste ~30% of our total food supply, equating to roughly $161 billion worth of food wasted every year. Composting provides a resurrection to such profligacy. The recently introduced COMPOST Act would build out a $2 Billion composting infrastructure and create USDA conservation programs centered around compost production and application on farms. Innovations like Dr. David Johnson’s fungal compost bioreactor and Malaysian startup Maeko demonstrate that the efficacy of composting can be improved.
Various cities and community initiatives have also built out successful composting projects (which can be partially found between here or here). Funding composting programs with immense environmental and social externalities, be it from patient private capital who can bear the high startup costs and foresee a future in ecosystem services or from a more robust federal public policy program on composting, will help us close the gap in our circular food system and lead to constant - and material - soil regeneration.
Listen: In this episode of the In Search of Soil Podcast, permaculturalist Diego Footer speaks with Randy Ritchie, CEO and founder of Malibu Compost, the makers of the first certified Biodynamic compost in the United States. This episode explores what makes high-quality compost and how the composting business works. This inside look at the composting can empower producers and consumers alike to take a fresh perspective when purchasing compost and soil amendments, as well as diving into compost teas, the importance of compost to farm self-sufficiency, and the greater story that led Randy to the composting world. If you find this episode interesting, I might also recommend Diego’s interview with Dr. David Johnson exploring microbes and fungal-dominated compost.
Dine: Zero Foodprint (ZFP) is a nonprofit organization mobilizing the food world around agricultural climate solutions. ZFP members crowd-fund grants for farmers to switch to regenerative farming practices—proven to be the most impactful initiative yet towards solving global warming. By committing 1% of their revenue, along with consumers contributing 1% of their bills, a few cents from each meal creates a Table-to-Farm Movement, helping farmers implement regenerative practices and build healthy soil. Local independent conservation experts help implement and verify each carbon farming project. ZFP restaurants are tackling the climate crisis with better food. Find a list of ZFP restaurants here and listen to this interview with Anthony Myint, director of partnerships at ZFP, to learn more.
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