Reducing "Pond Scum" - Don't Fertilize Too Much

Pond Scum

Is your neighborhood's stormwater retention basin growing a layer of pond scum similar to what you see in this photo? If so, it's quite possible that too many people are using too much fertilizer on their lawns in your neighborhood. Lawn fertilizers usually contain phosphorous and nitrogen, nutrients that plants need to grow. The downside to fertilizer is that feeding your lawn too many nutrients can cause "pond scum" in nearby water bodies. Pond scum is an indication of excessive nutrients in the water. When it rains, excess nutrients from fertilizer can run off your lawn and promote pond scum, which can cause odor problems and consume oxygen in the water, suffocating fish and other wildlife.

You can help fight this problem by using caution when fertilizing your lawn. Follow product label instructions carefully, apply the fertilizer accurately, and sweep excess fertilizer off of any hard surfaces back into your grass after application. Also, don't fertilize before rain is expected. A good idea is to test your soil to see what nutrients your lawn needs before fertilizing. The University of Missouri Extension office at 260 Brown Road in St. Peters provides a soil testing service that will give you fertilizer recommendations for a fee.

The extension office also can give you tips on what time of year to fertilize your lawn-for example, September is the best time for many cool-season grasses such as fescue.