Mowing – Grasscycling
Grasscycling is the act of allowing grass clippings to remain on the lawn after mowing to return nutrients back to the soil.
The fertilizer content of typical grass clippings (by percent of weight) is: Nitrogen (N) = 4%, Potassium (P) = 2%, and Phosphorus (K) = 0.5%. Grasscycling throughout the mowing season can actually reduce your need for fertilizers by as much as 25%. Grass clippings are thus too valuable to throw away.
A standard discharge lawn mower, with either rotary or reel type blade configurations, can be used for grasscycling without problems as long as you follow the one-third rule. Mulching (grasscycling or recycling) mowers are specifically designed to finely chop grass clippings and return them to the lawn to return nutrients to the soil.
Some rotary mowers offer multiple options, allowing you to use standard discharge, to mulch clippings, or to collect clippings in a bagging unit for disposal.
Grasscycling also saves the labor of collecting and bagging clippings and it reduces the “yard waste” component in landfills.
Based on a 1992 study, the U.S. Environmental Protection Agency (US EPA) estimated that “yard trimmings” including grass clippings, leaves, branches, brush and other plant materials, accounted for 17.9% of the total municipal solid waste, by percent of weight.
Since 1960, when yard trimmings accounted for 22.8% of the total, this percentage has declined each decade, as follows: 1970 - 19.0%; 1980 - 18.2%; 1990 - 17.9%. Grasscycling is the primary reason these percentages have dropped – and continue to drop.
Most, if not all, studies of municipal solid waste are based on curb-side or landfill destination truck weights. Accordingly, 100 pounds of grass clippings weigh the same as a 100-pound refrigerator and they would be considered “equal” contributors to a landfill.
However, grass clippings are 90% water. The remaining 10% is very degradable, unlike the refrigerator and many other landfill components such as plastics, metals, glass, construction debris, etc.
If calculated at their dry weight, grass clippings would not be more than 2% of the total landfill volume and this volume will biodegrade very rapidly, helping to improve landfill soils and assist in degrading other organic matter.
Mowing 1,000 square feet (92.9 square meters) of lawn will generate 200 pounds (90.718 kg) of clippings annually. One ton (.9 metric ton) of clippings will contribute only 200 pounds (90.718 kg) of decayed matter to a landfill.
But why would you want to expend the time and labor to collect and dispose of grass clippings, when grasscycling is such an obvious benefit to your lawn – and the environment? Grasscycling saves cents and makes good sense.