As the fall colors start to fade and leaves drop to the ground, it's a common habit to bag them up – but those leaves can be very beneficial to the environment.
Leaves contain nutrients and organic material. When they decompose, they act as a natural mulch, as those nutrients go back into the soil and improve it for future plants and grasses. The U.S. Department of Agriculture also reports that leaves can help prevent weeds.
“It makes a healthier, looser, more open soil,” said Susan Barton, a professor of plant and soil sciences at the University of Delaware.
They also provide a home for many insects and pollinators over the winter – which, in turn, creates a food source for birds. For the ones that make it through the winter, they help keep unwanted pests out of gardens in the spring and summer.
“We need to be landscaping our properties in a way that provides ecosystem services, you know, we’re not going to get it (the nutrients/leaves) from a shopping mall,” Barton said. “It's really important to maximize the carbon sequestration and the air quality improvement and the water infiltration and the wildlife support and all of those things that a rich layer of leaves provide.”
She added that even in places with heavier, clay-based soil, like Colorado and New Mexico, leaves can help improve the soil structure, providing better drainage and aeration.
All that is needed is a light scattering of leaves. If the covering is too thick, it can actually block the grass and plants underneath from receiving sun.
Bagging them up does a lot more harm. The Environmental Protection Agency reports that yard trimmings accounted for 10.5 million tons of waste in landfills in 2018. When leaves and other organic waste decompose, methane is emitted, causing further pollution to the atmosphere.
“We need people to think about leaves as a resource, not something to get rid of,” Barton said.
There are some compromises for those who do not want tons of leaves on their yard. Raking the leaves to other areas of the property or into a garden can help other soil areas besides lawns. It’s important to remove them early before the insects start to make their home in them.
Another solution is to use a mulching mower to chop up the leaves to lessen the covering and help them decompose faster. Or, some homeowners might choose to compost the leaves in a big pile or donate them to an official composter. The EPA also reported that 22.3 million tons of yard trimmings were composted in 2018.
Barton said we need to start viewing leaves as an important part of the natural process on the landscape.
“Nobody's raking up those leaves in a forest or in a meadow or a prairie,” she said. “In a forest, the leaves fall and they get recycled into the ground, and that's the healthiest soil that there is … letting those leaves decompose and go back to the soil system is a really important process that we need to encourage.”
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
