Managing Your Lawn for a Cleaner River

Steps you can take to protect the Assabet River and other local waterways.

Got topsoil? Check the depth and quality of your topsoil. A healthy lawn requires at least 4-6 inches of good topsoil. Deep, healthy soil is the foundation of a healthy, low-maintenance, non-polluting lawn. Adding organic matter such as compost by tilling or top-dressing is an excellent way to improve soil health and texture. In sandy soils, the addition of compost will improve water and nutrient retention; in heavier clay soils, it will improve drainage and aeration. Thoroughly mixing compost into the soil will also enhance and enlarge the root zone for grass plants. This is important for the long-term health of your grass plants because a deep and extensive root system will help grass to weather droughts and other stresses. Ideally, soils should contain about 10% organic matter.

Test your soil

Measure the pH of your lawn, how acidic or basic the soil is, and the amount of nutrients, such as phosphorus (P), and organic matter that it contains. UMass Extension offers low-cost soil tests; soil test results include recommendations for pH and nutrient adjustment. For more information, call the UMass Soil Testing Lab at (413) 545-2311, or find them on the web at www.umass.edu/plsoils/soiltest.

Apply only the type and quantity of nutrients your lawn needs, and adjust the soil pH if necessary
Bring your soil test with you when shopping for fertilizer. Click here for a list of garden centers and nurseries in the area that can help you interpret the UMass soil test results and select the right fertilizer for your lawn. Adjusting soil pH may also be necessary to help grasses grow better.

Keep fertilizer and water on your lawn where it is needed

Use Slow Release Fertilizers
Quick-release, water soluble (inorganic) fertilizers become available to plants almost as soon as they are applied to the lawn. The overall effects, however, are short-lived and sometimes harmful to the lawn's long-term health. For example, a water soluble (inorganic) nitrogen fertilizer will produce rapid leaf and shoot growth, but it may also cause excessive leaf and shoot growth, reduced root growth, and leaf burn, making the grass plants more susceptible to drought and disease. Moreover, these water soluble fertilizers are easily washed away by rain. Slow-release, water insoluble (organic) fertilizers produce green lawns without excessive leaf and shoot growth, or the risk of leaf burning. They are designed to provide a steady supply of nitrogen to the grass over a longer time period. And they are less likely to wash off lawns or down into groundwater because they are water insoluble.

What to Look for When Shopping for Fertilizer
Most lawn fertilizers contain a blend of the three major nutrients that plants typically need, nitrogen (N), phosphorus (P) and potassium (K). The amount of each nutrient in the fertilizer is printed on the bag as a ratio, for example, a "2-3-3" fertilizer contains 2% nitrogen (N), 3% phosphorus (P) and 3% potassium (K). In addition to the nutrient ratio, the bag will usually tell you the percent of each nutrient that is water soluble (inorganic) and water insoluble (organic). The amount of soluble versus insoluble fertilizer is important because water soluble or "quick-release" fertilizers are much more likely to wash off your lawn and down a stormdrain. Water insoluble or "slow-release" fertilizers, which depend on microbial and chemical action in the soil to make nutrients available to plants, take longer to become available to plants, but they sustain plants over a longer time period.

Organic fertilizers are water insoluble, slow-release fertilizers. Many organic fertilizers also contribute organic material and micronutrients to the soil. There are some synthetic (manufactured) slow-release fertilizers available as well. Grass plants, however, can only take up specific forms of phosphorus and nitrogen. Both water soluble and water insoluble fertilizers ultimately provide them with the same usable forms of nutrients to plants, but the water insoluble fertilizers are less likely to wash away and are longer lasting sources of nutrients.

For more detailed information about fertilizers, click here to find list of web sites.

Don't Let Your Fertilizer go Down the (Storm) Drain!
Do not fertilize before a heavy rain. The fertilizer will wash off into the street and enter the nearest waterway.

Vegetated Buffer Strips
Maintain a natural vegetated buffer strip between your lawn and your street and driveway to reduce soil erosion and the transport of fertilizer-enriched rainwater from your property. This buffer should be as wide as possible and planted with deep-rooted, shrubs and plants. Consider planting native shrubs and plants as they are well adapted to local soils and climate.

Mow High and Mow Often. Mow your grass 3 inches high or put your mower on its highest setting, and make sure your blades are sharp. Tall, dense grass shades out weeds. Tall grass is usually healthier than short grass because it has deeper roots and more stored sugars, which helps the grass to resist disease, pests, and drought and make more grass plants.

Recycle your grass crop. Leave grass clippings on your lawn. Grass cuttings are a cheap source of slow release nitrogen fertilizer that adds organic material to your soil. If you prefer to remove grass clippings from your lawn, compost them. Next time you need a mower, consider buying a mulching mower that chops grass into very small pieces. Don't dump grass clippings or other yard waste into wetlands or near ponds, lakes, streams or rivers. As the yard waste decays, rain will wash nutrients from the wastes into waterways.

Water infrequently, but deeply. Water only when needed, but water longer, so that water penetrates deeper into the soil allowing the roots of grasses to grow deeper into the soil. When there is a dry spell, these deeper roots will still be able to feed the grasses. Frequent, short watering causes grasses to grow shallow root systems that become easily stressed during a dry spell. Your lawn usually needs watering when the grass curls and/or when foot steps on the lawn leave visible impressions.

Plant lawn areas that aren't needed or used with low-maintenance woodland gardens, flowers or shrub borders. Ask yourself, how much lawn do you really want to maintain? Plant lawn areas that aren't needed or used with low-maintenance, native shrub and flower borders or woodland gardens. There are many alternatives to lawns that require less fertilizer and water. They will also enhance your landscape's beauty and natural plant diversity, and attract birds, butterflies and other wildlife.

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To learn about OAR's programs that target the Assabet's issues, check out OAR Programs.