By Angie Hong
Reprinted from the blog East Metro Water, Tips and Tales about Keeping Water Clean, Nov. 1, 2016
It turns out that raking leaves off of your lawn can actually be counter-productive. “The leaves have organic matter in them,” Bauer said in an interview with the Washington Post. “You’re adding good organic matter to your soil when you’re not picking them up.” Instead of raking, Bauer recommends that you mow your lawn a few times as the leaves are falling to break them up into little pieces that decompose more rapidly. If you have a very heavy coating of leaves, you may need to remove some and add them to your gardens or compost pile, but the rest can be shredded and left where they are.
Leaves contain vital nutrients like phosphorus, nitrogen, and potassium that turf grass and other plants need to grow. In fact, these nutrients are the exact same ones found in compost and commercial fertilizers. Leaves, however, are free and readily available to most Minnesota homeowners. During the course of the winter, the leaves decompose under the snow and release nutrients into the soil. In addition, research at Michigan State University suggests that leaf litter can help to suppress weeds like dandelions from growing the next spring. On their own test plots at University of Minnesota, Extension experts like Bauer have found that mulching your leaves in the fall, as well as leaving grass clippings on the lawn during the rest of the year, provides enough nutrients to replace one standard application of fertilizer per year.
While the nutrients in leaves might be good for your lawn, they can still spell trouble for local wetlands, lakes, rivers and streams when they end up in the street. Leaves wash into storm drains that connect to local waterways, and the phosphorus and nitrogen released feeds algae in the water. This contributes to more algae blooms and poorer water quality the next summer. In addition, fall rains can turn leaves in the street into a soggy mess that clogs up storm drains and contributes to localized flooding. Some people make the mistake of dumping their leaves into nearby wetlands or ravines that drain to rivers and streams, because it seems like an easy and natural way to get rid of them. Instead, the leaves send a pulse of nutrients into the wetlands and streams and can make the water turn green and slimy in the spring. For this reason, most cities have ordinances that prohibit residents from dumping leaves and other yard waste into wetlands and buffer areas.
So why do so many people rake their lawns each fall if it’s actually better to leave the leaves there? According to Bauer, people tend to do things out of habit regardless of whether they’re actually useful. “Everyone thinks that your lawn needs to be watered every other day, too,” he said. My advice? Skip raking the lawn and use your energy to sweep the leaves off of the driveway and out of your street instead. Also, you still need to eat your broccoli.
Angie Hong is an educator for East Metro Water – www.mnwcd.org/emwrep – which includes Brown’s Creek, Carnelian Marine – St. Croix, Comfort Lake – Forest Lake, Middle St. Croix, Ramsey Washington-Metro, Rice Creek, South Washington and Valley Branch Watersheds, Cottage Grove, Dellwood, Forest Lake, Grant, Hugo, Lake Elmo, Newport, Oak Park Heights, Oakdale, Stillwater, St. Paul Park, West Lakeland, Willernie and Woodbury, Washington County and the Washington Conservation District. Contact her at 651-330-8220 x.35 or email@example.com.
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