Want to reduce waste and time? Try mowing leaves rather than removal
Published: October 4, 2013
When moving from Michigan to Missouri some years ago, Michigan State University Extension began promotion of mowing leaves as an alternative to
Want to reduce waste and time? Try mowing leaves rather than removal
Published: October 4, 2013
When moving from Michigan to Missouri some years ago, Michigan State University Extension began promotion of mowing leaves as an alternative to raking them. My Missouri home had a plentiful lawn relative to the amount of leaves dropped, so after practicing this for 10 years, I wondered- is this practice still suggested and have there been any follow up studies on the effects to the soil or turf quality?
Burning of leaves in cities and towns has declined dramatically since the 1970 passage of the Clean Air Act. In the late 1980’s concern developed over the amount of yard waste ending up in landfills, resulting in many states banning yard waste from landfills (e.g. Missouri 1992, Indiana, 1994; Michigan, 1995). While commercial or municipal compost sites developed in response to the situation, some cites have focused on how commercial sites and homeowners could reduce the amount of yard waste they send off their property.
Maintaining a regular mowing schedule in the fall was an idea that appeared to save time and reduce the volume of yard waste. For mowers with bagging units, collecting the chopped leaves and using them as mulch around trees and shrubs is a great option. But capturing the shredded leaves takes time, and many individuals do not have ‘bagging’ mowers. (Mowing the leaves and grass clippings into a ‘windrow’ and then raking them up is an acceptable compromise, but still takes more time.)
Studies in Michigan were conducted in the 90’s to evaluate the effects of leaf mulching on turf, under various conditions. The first study considered three different leaf application rates (none, 3 inches, and 6 inches) of mixed tree species, mulched in with a rotary mower using two passes in October. It also considered 2 different nitrogen applications (2 or 4 lbs of nitrogen/1,000 sq ft). A second study used leaves from maples or oaks. Both studies were done in full sun with Kentucky bluegrass lawns. Michigan State scientist did note that while the nitrogen application improved the turfgrass quality rating, it did not seem to speed the decomposition of the leaves. It was also pointed out that chopping leaves into small particles was important and allows them to filter into the turfgrass canopy making better soil contact.
What about soil quality? In a 1998 study at Michigan State, soil from these various plots were analyzed. Soil pH did not change, but organic matter did increase in response to the leaf mulching. Composition of the grass clippings was also affected; the percentages of carbon and nitrogen both increased with leaf mulching, but the ratio of carbon to nitrogen stayed constant, which is positive. If nitrogen had been reduced, a decline in turfgrass vigor or color may have occurred.
Purdue University also conducted a study considering the effects different leaf application rates may have on tur