By Perry Thomas and Michaela Lambert
As days shorten and temperatures drop, Kentuckians prepare lawns and gardens for winter. Whether fertilizing or raking, this is a great time to economize while protecting waterways from excess nutrient runoff.
Small steps taken by many of us can help speed progress toward meeting the goals of the Division of Water’s recently released Nutrient Reduction Strategy. Excess nutrients that run into our waterways spur faster algal growth and may lead to harmful algae blooms (HABs), either locally or downstream.
In a 2020 KYH2O podcast, Nutrient Management in Lawn Care, UK Assistant Professor of Plant and Soil Sciences Travis Shaddox emphasized the importance of knowing our soils well to optimize nutrient application.
“In Kentucky, we are very blessed to have extremely fertile native soils,” Shaddox said. “In most cases, we don’t need to apply phosphorus, potassium, magnesium, or calcium to any of our lawns.”
Adding extra nutrients will not improve grass or garden growth, and soil tests are strongly recommended to determine what nutrients, if any, are needed.
Local county extension agents can help by providing soil sample bags and interpreting results. Routine soil tests cost less than $10.
Applying only those nutrients needed may save money and reduce the possibility of excess nutrients entering our streams.
Timing of nutrient application is also important. UK Extension recommends applying fertilizer in the fall for cool season lawns (fescue and bluegrass), trees and shrubs. They suggest fertilizing before a rain event to help prevent fertilizer burn, but Shaddox warns that applying nutrients before an intense or prolonged storm may result in losing fertilizer downstream due to stormwater runoff.
Another way to prevent fertilizer burn is to consider using organic fertilizer or homemade compost.
Leaves and lawn clippings can be used as mulch or added to compost.
According to research by several land grant universities and documented by Kansas State University extension, mulching yards with leaves requires simply mowing when a thin layer of leaves accumulates and instead of capturing the clippings, returning them to the lawn.
Repeat this process during the fall until approximately six inches of leaves have been mulched into the lawn. Subsequently, mow to chop leaves and then take a second pass with a bag attached to capture them. It’s important not to rake leaves into streets, as they can then clog stormwater drains or contribute their nutrients to local streams.
The EPA recommends applying captured leaf matter and grass clippings directly as mulch in gardens or composting them for later application, and you can continue composting in winter. Using these amendments instead of store-bought mulch in our gardens and yards is another way to save money.
Synthetically treated lawns may not have the microbes needed to break down leaf matter or grass clippings. Collecting the leaves and clippings for compost works best in these cases. According to Oregon State University Extension, microbes play an important role in breaking down coarse nutrients to a form that is usable by plants. Practices for restoring and supporting healthy microbes include using organic compost, incorporating native vegetation into landscaping, and eventually adding leaf mulch.
For more information about healthy lawn management practices, visit the University of Kentucky’s Turf Management page.
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