In 1990, American landfills buried about 25 million tons of grass, leaves, and branches a year. By 2018, that figure had fallen to roughly 10.5 million tons, even though households and businesses were generating slightly more yard waste than they had three decades earlier, according to EPA’s material-specific data on yard trimmings.
Yard trimmings are the rare waste stream where the collection and reuse system mostly worked. Many municipal recycling programs have launched successful side businesses selling compost and soil made from recovered yard waste.
State landfill bans, a generation of municipal composting programs, and the simple act of leaving grass clippings on the lawn turned what had been the single largest organic material in the trash into one of the most-recovered. The country now composts or mulches 63 percent of its yard waste.
But “mostly worked” leaves an asterisk: the material still going to landfills is disproportionately the fast-rotting grass and leaves that generate methane faster than landfills can capture it.
A Quarter of the Landfill, Reclaimed
The scale of the yard-waste collection success is easy to miss because it happened slowly. In 2018, the U.S. generated 35.4 million tons of yard trimmings—grass, leaves, and tree and brush trimmings—12.1 percent of all municipal solid waste. Of that, 22.3 million tons were composted or mulched, which represents a 63 percent recovery rate. That is one of the highest diversion rates of any major material in the waste stream, and it represents a near-total reversal from 1990, when only 4.2 million tons were composted and more than 25 million tons went to landfills.
Three forces drove the change. Many states have restricted or banned yard trimmings from landfills, some for decades—Pennsylvania since 1990, Minnesota since 1994, and West Virginia since 1997, as the Institute for Local Self-Reliance documents—and California now requires yard materials to be diverted statewide under its organics law, SB 1383, which took full effect in 2022. Municipal composting and curbside collection gave residents somewhere to send yard debris when it is separated from other household waste.
And grasscycling, which means leaving clippings on the lawn instead of bagging them, quietly removed a large share of the material from the stream before it ever reached a truck.
The payoff is more than empty landfill space. Composting returns nutrients and carbon to the soil, and because it is a fundamentally local process—organic material is usually collected and processed in the same county, city, or neighborhood—it also supports local jobs, as EPA notes in its overview of composting.
The Methane Asterisk
Nevertheless, 10.5 million tons of yard trimmings are still landfilled each year, representing 7.2 percent of everything in U.S. landfills. They matter more than their tonnage suggests. Municipal solid waste landfills are the third-largest source of human-related methane emissions in the United States, responsible for about 14 percent of the national total in 2022. Organic materials, such as food waste, yard trimmings, wood, and paper combined, make up 51.4 percent of what gets landfilled, and when they decompose without oxygen, bacteria convert them into methane, a greenhouse gas 28 times more potent than carbon dioxide.
Yard waste’s particular problem is timing. It decomposes before landfill gas-collection systems are installed and activated as the space is filled and capped, often years later after organics are buried. Fast-decomposing, wet material like summer grass clippings largely breaks down before that capture equipment is running, which means much of its methane escapes uncollected.
“ If there is no immediate gas capture system, it is likely that all of the fresh wet materials will have significantly decomposed before the gas collection system gets turned on,” wrote University of Washington soil scientist Sally Brown in a BioCycle analysis of landfill gas environmental impacts.
Not all yard waste behaves the same way, and the difference changes how it should be handled. Woody material, including branches and wood chips, is high in cellulose and other slow-degrading compounds; in a dry sanitary landfill it can sit nearly inert, effectively storing its carbon rather than releasing methane. Grass and leaves are the methane drivers.
What It Costs Your Household
A household that bags yard waste and sets it at the curb often pays twice: once to haul the material away through bag fees, sticker tags, or collection charges, and again to buy back the same nutrients as fertilizer, mulch, and compost.
The avoided purchases add up at retail prices. A 40-to-45-pound bag of compost runs $3 to $10, bulk compost is $20 to $50 per cubic yard, and mulch is $15 to $65 per cubic yard before delivery, according to HomeGuide’s 2026 cost data. A household that composts its own leaves and clippings sidesteps much of that spending.
Grasscycling closes that loop on the lawn. Clippings left in place supply up to 25 percent of a lawn’s annual fertilizer needs and contain roughly four percent nitrogen, two percent potassium, and 1 percent phosphorus, according to University of Missouri Extension. Mowing a little taller to make grasscycling work also produces deeper roots and reduces watering.
For most households the direct dollar savings are modest—tens of dollars a year, not hundreds—and they depend on whether you garden enough to use what you make. The labor savings from skipping the bagging, and the soil and water benefits over time, are where the real value compounds. Leaving biomass in your yard means those nutrients don’t need to be replaced by synthetic fertilizers, which could save hundreds of dollars a year.
The Template Other Organics Haven’t Matched
The contrast with food waste shows how far the yard-waste model still has to travel across the rest of the organics stream. Food is the single most common material in U.S. landfills and is responsible for 58 percent of landfill methane emissions, yet only about 5 percent of wasted food is composted.
Yard trimmings, in other words, are the proof of concept. Landfill bans, accessible collection, and a behavior change as simple as leaving the clippings where they fall moved a major organic material from the dump to the soil in a single generation. The methane asterisk is a reminder that the job is not finished, and that the fastest-rotting share of what is left is the part most worth diverting first.
What You Can Do
- Leave clippings on the lawn. Mow when the grass is dry and remove no more than a third of the blade so small clippings fall to the ground and break down quickly.
- Mulch leaves in place. Run a mower over fallen leaves rather than bagging them; the shredded leaves feed the soil and suppress weeds.
- Compost at home. Check out our guide to the types of composters available and how to balance your compost with carbon-rich “browns” (dry leaves, wood chips) with nitrogen-rich “greens” (grass, food scraps) at roughly a 2:1 ratio of browns to greens, and keep the pile as moist as a wrung-out sponge.
- Use curbside or drop-off collection. Where it is offered, keep yard waste source-separated and out of plastic bags so it can actually be composted.
- Buy and use local compost. Closing the loop on the nutrients cuts both fertilizer and water use.
- Push for policy where composting is needed. If your state or city still landfills yard trimmings, support landfill bans and curbside organics programs, the policies that drove the national turnaround.
- Find a local option. Look up nearby composting and yard-waste drop-off through Earth911’s recycling search.
The post Yard Waste: Composting’s Success Story With a Methane Asterisk appeared first on Earth911.
- Source: https://earth911.com/how-to-recycle/yard-waste-compostings-success-story-with-a-methane-asterisk/
