Urban Composting: A Complete Guide

Urban Composting: Food waste, and the handling of other types of organic waste, represents a serious problem. Around the world, several cities are taking steps to address these concerns. Success varies, but is nonetheless inspiring. With luck and determination, this is a movement that will catch on and spread.

By S. Mathur

Urban Composting: Introduction

One of the things I miss most about living on a farm is feeding most of my kitchen scraps to the chickens and tossing the rest on the compost heap. There’s no waste, very little trash, and you close the loop with a neat, natural solution. Urban dwellers, however, don’t have this handy barnyard option, and have to work at it if they want to recycle their organic waste.

There are kitchen countertop composters, but these are not always practical. Most apartment dwellers are short of kitchen space, and they may not even have a use for the compost they generate. Which is why so much organic waste ends up in the trash, and eventually in landfills or incinerators. But this is not just a small matter of inconvenience for city dwellers.

In landfills, organic matter decays and releases methane, one of the strongest greenhouse gases. So it’s not just our methods of disposing of inorganic non-biodegradable plastics that pollute the environment. The disposal of organic, biodegradable waste too creates a host of problems.

The solution is actually quite simple. In a few locations across the US, residential organic waste is being turned into soil- enriching compost. Some cities and commercial trash management companies have started curbside pickup of organic compostables in separate containers from trash and recycling. The compost generated from this organic waste is sold for use by area farmers, with multiple benefits in terms of food quality and a reduction of chemical inputs in agriculture.

The Problem: Getting Rid of Organic Waste

It’s not just putting non-biodegradable materials in the trash that creates massive environmental problems; the disposal of organic biodegradable waste in the trash also has a negative impact on the environment. Most households produce quantities of organic waste like kitchen scraps, paper, and yard trimmings. When these are dumped in landfills, without access to light or air, they decay and produce the greenhouse gas methane. Methane is one of the strongest greenhouse gases and, according to the EPA, landfills are the third largest source of methane emissions in the country.

Compostable organic waste makes up as much as 30% of the total material sent to landfills and incinerators in the US (more info: the science of composting). If these materials were composted instead, they would decompose to form a nutrient-rich mixture that can be used by farmers to raise organic produce. Many cities and towns already have laws requiring household and commercial organic waste to be disposed of in separate containers from trash and recycling, so it can be brought to composing centers.

Mobile chicken shed, with farmer feeding free ranging chickens
Spring Creek Farms Pastured Livestock
Credit: Cynthia van Elk
A red farm building at dusk: Farms are the key to urban composting
Midwest Organic Center at Eztel Sugar Grove Farm
Credit: Rodale Institute

On The Way To Zero Waste

Perhaps unsurprisingly, San Francisco leads the way, and had a municipal composting law in place in 2009, requiring residents to sort their residential waste into three bins instead of the two to which most people have become accustomed. Besides bins for trash and recycling, there’s a green bin for compostables, which actually account for most domestic waste. The compostables are taken to a sorting and composting facility by Recology, the private trash collection company that manages the city’s waste.

The facility produces around 350 tons of compost every day, which is available for area farmers who want an alternative to synthetic fertilizers. This has brought San Francisco within reach of its goal of going zero waste by 2020. Other cities too have similar program, including Portland, Boston, New York and Nantucket Island in Massachusetts.

Besides municipal services, some private waste management companies have also started collecting compostables along with residential trash and recyclables in urban neighborhoods.

Bringing It Back To The Farm

Zero waste is an ambitious enough goal, but the payoff from urban composting can be even bigger. There is the possibility of closing the loop by making cities part of the natural cycle, by producing enough compost for large-scale agricultural use. And then there are the environmental benefits of using organic compost instead of synthetic fertilizers, including better soil quality, less soil erosion and less nitrogen and phosphorous pollution in water bodies due to runoff from fields.

Turning urban trash into compost follows the way nature works, using waste materials to fertilize plants and enrich the soil. Compost-rich soil is dramatically different from soils depleted by decades of chemical inputs, and its potential can move strong men to poetry. It contains the nutrients and microbes that make up the rich humus needed to raise healthy crops. Recology’s San Francisco Mix is bought by area farmers, who can choose from several different varieties depending on the crops they’re planting, or even ask for custom-made compost.

Commercial farms have also discovered the hard way that soil fertility declines even with heavy chemical inputs. Fertilizer inputs reach the point of diminishing returns in a few years, and the depleted soil is also more prone to erosion by air and water. Commercial farms already have to bring in compost needs to restore soil quality and maintain crop yields. Using locally-produced compost closes the loop on a societal scale, turning waste into nutrition in a manner that mimics natural processes.

Large-scale urban composting could potentially transform the chemical dependence of American agriculture, by supplying enough rich, natural compost to support organic farming nationwide. Transitioning to natural compost instead of synthetic fertilizers will produce food that is healthier; it will also cut down on air and water pollution.

Supporting Organic Agriculture

Skeptics who question the viability of organic agriculture can look at the long-running study at the Rodale Institute that compares agricultural outputs using organic versus conventional methods. Its findings include the following: crop yields are comparable within five years of going organic; organic agriculture yields are 40% higher under drought conditions; organic systems produce 40% lower carbon emissions than conventional systems; and organic inputs don’t leave behind harmful chemicals in the soil, air and water.

Better soil health results in better water retention in the soil, and less runoff into water bodies. This helps to reduce the problem of excess nitrogen and phosphorous from fertilizer ending up in water bodies and producing algae blooms – some of which can be toxic – and eventually dead zones. Using compost actually reverses the cycle of air pollution as well, by fixing excess nitrogen and carbon in the soil, removing them from the atmosphere. The Rodale Institute study found that when combined with cover crops, just one acre of land under compost made from urban scraps can pull 12,000 pounds of carbon out of the air and into the soil in a single year.

farm in distance with green fields
Rodale Institute
Credit: Rodale Institute
comparison of organic and conventional soil
Organic and Conventional Soils from the Farming Systems Trial
Credit: Rodale Institute

Why Doesn’t My City Compost?

With so many benefits from urban composting, there’s just one more question left to ask, and it’s the obvious one. Why isn’t everyone doing it? As of 2019, a US PIRG report counts 150 locations in 16 states that have some kind of urban composting programs. So what about the rest?

Setting up large-scale composting pick-up and processing systems can be expensive and requires commitment of resources, people and land. Local governments can be slow to learn and clunky to move. However, a number of startups and waste management companies have also started their own urban composting pick up programs, which operate on a smaller scale than municipal composting. There may be one near you. And if there isn’t, what a great idea for a start-up!

Urban Composting chart
Image source: https://www.recology.com/recology-cleanscapes/issaquah/sorting-guides/