When people think about solutions to food waste, composting is often one of the first ideas that comes to mind. And for good reason — composting plays an important role in reducing what ends up in landfills and returning nutrients back to the soil.
But composting is only one piece of a larger system. Understanding what composting is, what it is not, and where it fits within the broader food waste conversation helps communities make more informed decisions about how to reduce waste effectively.
That matters in Memphis, where approximately 1.7 million tons of waste are produced across Memphis and Shelby County each year. About 38% of landfill waste locally is food waste, and the average resident generates roughly 1,800 pounds of waste annually.
Many of those materials that are thrown out are compostable — the question then becomes, how do we handle them before they reach the landfill?
What composting is
Composting is the natural process of breaking down organic material into a stable, nutrient-rich soil amendment known as compost. This process relies on oxygen, moisture, microorganisms, and time to transform food scraps, leaves, grass clippings, and other compostable materials into something that can improve soil health and support future plant growth.
There are several common composting methods, including:
- Backyard or home composting, often used for fruit and vegetable scraps, leaves, and yard waste
- Commercial composting, which operates at a larger scale and can process a broader range of materials
- Vermicomposting, which uses worms to help break down organic matter
- Aerated compost systems, which speed up decomposition by increasing airflow
When done properly, composting helps divert organic material from landfills while creating a useful product that can support local soil health.
What composting isn’t
As interest in waste diversion grows, many technologies and processes are marketed as “composting,” even though they function differently. For example, material that has simply been ground up, dehydrated, or liquified through devices like residential food dehydrators or commercial biodigesters is not considered compost. While these technologies may reduce volume, the resulting material is often still biologically active and has not completed the process required to become finished compost.
Similarly, material created through anaerobic digestion, a process that breaks down organic matter without oxygen, is different from composting. Anaerobic digestion can generate energy and reduce waste, but it produces materials like digestate or biosolids rather than finished compost.
That distinction matters because compost is specifically defined as a stable product created through aerobic decomposition. Some of these byproducts can still be valuable; digestate and biosolids, for example, may later be composted or treated before being applied to land. When managed properly, they can help offset the need for synthetic fertilizers and support healthier soils. The key is understanding that not all waste diversion processes are interchangeable.
When composting helps
Composting is most effective when it is used for materials that can no longer serve a higher purpose. The EPA’s Wasted Food Scale outlines the preferred order for reducing the environmental impacts of wasted food.
At the top of the scale are strategies like preventing waste in the first place and donating surplus food to feed people. Feeding animals and repurposing food for other uses also rank above composting. That’s because composting still represents food that was not fully utilized.
A tray of prepared food that can feed people has more value as a meal than as compost. Likewise, surplus produce that can be donated or redistributed to those in need should remain in circulation whenever possible.
Composting becomes especially valuable for:
- Food scraps that are no longer edible
- Coffee grounds, eggshells, and produce trimmings
- Yard waste and landscaping materials
- Organic materials that cannot realistically be rescued or donated
In these cases, composting keeps organic material out of landfills and helps reduce methane emissions created by decomposition in oxygen-limited landfill conditions.
Part of a bigger system
The most effective systems prioritize using food for its highest possible purpose first: Feeding people whenever possible, then finding productive uses for remaining materials before they become waste.
That’s why food rescue, donation, composting, and prevention all work best together. Reducing food waste is centered on building systems that keep resources in circulation longer, reduce unnecessary landfill disposal, and help communities make better use of the food they already have.
