Dear Jay,
Those little green clippings seem innocent enough, and you'd think they'd just break down nicely like the fruit rinds in your backyard composter, but landfilling grass clippings, yard waste, and other organic items like food waste and paper actually contributes to global warming. (I know, you thought it was just a matter of adding to the landfill and now you learn you're warming the globe. Stay with me, there's better news coming.)
The reason these materials contribute to global warming is that in a densely packed and covered landfill they don't have access to the elements -especially oxygen-that help them break down in an aerobic process (unlike a well-functioning compost pile). In the absence of air, sun and rain, organic materials like grass clippings decompose anaerobically (without oxygen) and create methane, a potent greenhouse gas 21 times more effective at trapping radiant heat than carbon dioxide. According to the Union of Concerned Scientists, the number-one source of human-caused methane emissions to the atmosphere is buried waste. In fact, landfills contribute 10% of the gases that are warming the globe. For this reason, many countries around the world and some U.S. communities have made it illegal to landfill yard waste and paper.
The good news (I told you it would get better!) is that it's incredibly easy to avoid landfilling grass clippings while at the same time reaping the happy side effects of doing less work, saving on water usage, paying less for lawn maintenance and getting a healthier lawn! T he secret is to leave the clippings on the lawn, or to "grasscycle." Here's how: Every time you cut the grass, follow the "one third" rule. Mow often enough to cut only one-third of the length of the grass blade in any one mowing. T his strengthens the grass plant by reducing shock to the lawn's root system and creates a denser, healthier root system. Once you've mowed, let the clippings do their stuff. By leaving them on the lawn, you'll reduce your need for fertilizer. Grass clippings are 80-85% water and contain 2-4% nitrogen, phosphorus, potassium and other nutrients. According to the University of Colorado , grasscycling can reduce fertilization needs by 25 percent or more. You'll also see your water bill shrink because grasscycling provides an umbrella for your grass roots and keeps our harsh Colorado sun from drying them out. And of course you'll save your back and time since there'll be no raking and bagging.
Some worry that leaving grass clippings on the lawn will cause thatch, but thatch is an accumulation of the "woody" parts of the grass plant (stems and roots), not the clippings. T hatch is most often caused by over-watering and over-fertilizing. Grasscycling can actually make your lawn look healthier; many golf courses and parks have been grasscycling for years. Plus, you don't need a mulching mower, any mower will work if you simply remove the collection bag. Many mower manufacturers will sell mulching blades and adapter kits, that can improve your mower's grasscycling performance. You'll get your best grasscycling results when you mow more often and only when your lawn is dry.
There you have it. You go from mowing and bagging to saving money and time while preventing global warming. Not bad for a Saturday afternoon's work. Of course you can always go one step further and plant your yard with xeriscape plants and grasses. But that's another column for another day.
