By Dana Little, June 6, 2010
What could be more beautiful than a healthy green lawn? Let me suggest some alternatives: a garden of flowers, a collection of attractive bushes and a buffer strip of untouched land next to the lake for the wildlife. Why do we worry about lawns running right up to the lake? Because lawns are the major source of phosphorous run-off into the lake. In a buffer strip the rain water slowly percolates through the soil which naturally cleanses it of phosphorus. A lawn maintained right up to the pond’s edge allows rain to wash phosphorous off the surface of the soil directly into the pond. Fertilizers applied to the lawn provide another source of phosphorous run-off. Phosphorous in fertilizers is seldom needed and yet, is widely used. Maine Law now makes it illegal to sell phosphorous- containing fertilizers without notifying customers of the issue. Fertilizers with no phosphorous can be bought in all local stores and will not harm the lake.
So, if you must have a lawn, here are the experts’ top 10 recommendations:
- Fertilize only if necessary, once or twice, best in late August or September and then only on new or young lawns less than 10 years old. Only one-quarter to half the usual recommended amount is necessary. Pesticides and herbicides can run off into the pond hurting fish and water quality. Fertilizers that contain pesticides and herbicides increase the problem that can occur with “fertilizing” the lawn.
- Perform a soil test to determine which nutrients are needed. Seldom in Maine do you need phosphorous or potassium. Nitrogen is the only common nutrient needed and then not on lawns over 10 years of age. Mulching the lawn clippings on the lawn and mixing clover into your lawn seed provide all the nitrogen most lawns need.
- Mow high, at least 3 inches, for vigorous roots and to shade out weeds
- Use a mulching mower that will leave the grass clippings on the lawn for a high-quality, phosphorous-free fertilizer
- Plant the right species of grass. Avoid Kentucky Bluegrass which requires high levels of fertilizer and water and use turf-type tall and fine-leaf fescues. Grass seed mixtures ideally should include herbs such as chamomile, yarrow and clover. These “weeds”, often killed off with pesticide applications, take nitrogen from the atmosphere and make it available to the grass.
- Keep the grass dense. Higher density means fewer weeds. At the first sign of thinning, loosen the soil with a rake and apply an appropriate grass mixture.
- On older lawns that have been heavily fertilized thatch can build up. If the thatch is thicker than ¾ inch it can be reduced by a core aerator that punches holes in the ground or by applying 1/8 inch of compost over the entire lawn which will cause the thatch to decompose.
- Water your lawn only if it has rained less than an inch in the last week. Watering daily encourages shallow roots and an unhealthy lawn. Water once a week to provide for one inch over the entire lawn using a rain gauge to measure your sprinkler’s output.
- Keep fertilizers and clippings off sidewalks and driveways where rain can wash them into the pond.
- Keep mower blades sharp to prevent tearing of the grass which promotes disease.