After Kathy Sykes, a certified Master Gardener, submitted her opinion piece calling for a pesticides ban in DC, we had some questions for her, including: Are weeds in a grass lawn the main target of herbicides? Is lawn fertilizer harmful to humans? And what are some alternatives? Here are her answers.
Herbicides are a type of chemical pesticide designed to control or destroy plants, weeds, or grasses. They are not needed for healthy lawn. And they can be a detriment to our health.
Herbicides tend to have wide-ranging effects and can eliminate beneficial insects such as earthworms that are important to maintaining healthy soil and in turn healthy grass. And while the pesticides used in our country must be registered by the Environmental Protection Agency, there is no guarantee that they are safe to humans or the environment.
The EPA believes that no pesticide can ever be considered perfectly safe. In fact, of the 36 lawn pesticides, 14 are probable or possible carcinogens, 15 are linked to birth defects, 21 have reproductive effects, 24 have neurotoxicity effects and 22 can cause liver damage. Moreover, 34 have irritant properties.
Fertilizer can also be irritating if it gets into your eyes, nose, or mouth. It can cause stomach upset if swallowed. Usually, there are no other problems with the types of fertilizers sold for home use. But – and this is a big "but" – some fertilizer products also contain herbicides and insecticides.
Also: “The element phosphorus is an important component in fertilizers, and helps plants grow. Today we know that runoff from phosphorus-containing fertilizer used on land can also affect the ocean and contribute to algae blooms.” These algae blooms deplete oxygen levels, harming humans and aquatic life. For example, they are responsible for poor water quality negatively affecting blue crabs, oysters and fish.
Here are some steps you can take to create a healthy lawn without such chemicals.
Aerate the lawn. Compacted soil is an invitation for weeds. If you can’t stick a screwdriver into your soil, it is likely too compacted. You can rent an aerator together with your neighbors and once aerated, Mother Nature will take over. Earthworms will return, and birds will peck at your soil and aerate your lawn for free.
Don’t cut your grass too short. At least one and a half and one and quarter inches is ideal. Cutting the grass shorter kills the root system and opens up opportunities for weeds. Never mow more than a third of the blade of grass at a time, and ensure that the lawn mower has sharp blades.
Get the soil tested. Contact an extension service to test the pH of your soil and perform an organic content analysis. A soil test is the best way to understand the levels of nutrients available to plants. UDC CAUSES offers such testing starting in September.
Usually a soil test should be taken every three years to keep on top of changes in nutrient levels and soil conditions. Lawn soil should be slightly alkaline – between 6.5 and 7.0. And you should have organic content above five percent.
The test results will determine the kinds of fertilizers your lawn will need. Look for slow release organic fertilizers. The most common nutrient in lawn fertilizers is nitrogen, which promotes root development and growth. However, adding too much nitrogen or quick release fertilizers will change the pH of the soil, weaken the grass, and promote disease and insects and thatch buildup. (Thatch builds up when grass produces organic debris faster than it can break it down.)
Watch the watering. Overwatering, lightly watering too frequently, and poor drainage can also invite weeds. While watering needs are site specific, usually deep watering once a week in the early morning is best. The good news is once a yard has a deep root system from mowing high (not cutting the blades below one and three-quarter inches) the yard will need less water.
Make friends with weeds. A chart in this document from Beyond Pesticides lists common weeds and the conditions in which they take root on lawns. However, many of the weeds have beneficial qualities. For example, clover thrives in soil with low nitrogen levels. Clover captures nitrogen from the air and distributes it to the grass, promoting its growth. Crabgrass assists with erosion control.
Ditch the lawn altogether. Plant a pollinator garden! Ecologist Doug Tallamay stated in his book Nature’s Best Hope, “We need a new conservation toolbox… a cultural recognition that conservation is everyone’s responsibility, not just those few who make it their profession.”
He recommends that we convert at least half of the area now in lawn “to attractive landscapes packed from the ground to canopy with plants that will sustain complex food webs, store carbon, manage our watersheds, rebuild our soils, and support a diversity of pollinators and natural enemies.”
Much of this piece is drawn from the work of Beyond Pesticides, a DC-based nonprofit. You’ll find more information on lawn care hazards and alternatives on this page. And here’s a fact sheet on the eight steps to a pesticide-free lawn.