The demand for green lawns in the dry summer months can take a heavy toll on local lakes and streams.Excess lawn fertilizer and nutrients can be carried by runoff into storm drains. These drains lead to local streams and Lake Superior. According to LakeSuperiorStreams.org, “The same nutrients that help grass grow also help algae and pond weeds grow, leading to algal blooms and excessive aquatic plants that are not only unpleasant to look at and to swim in, but also affect food quality and habitat for fish and other organisms.”By following these water friendly tips from LakeSuperiorStreams.org, we can prevent runoff, save money, and still maintain a beautiful yard all summer long.
How can I responsibly use fertilizer?
1. Start with a soil test. Make sure your lawn needs fertilizer, and find out how much you should be applying. The Soil Testing Laboratory of the University of Minnesota website provides information on how to collect a soil sample and where to mail it. Your test results will include recommendations on what nutrients you should add to your lawn.
2. Choose the correct product. If you had a soil test, be careful to read the labels and buy the correct fertilizer. If not, consider using phosphate-free fertilizer (and therefore phosphorus-free). WHY?
- Lakes and streams may be phosphorus limited. When excess phosphorus from lawn fertilizer and other sources enters streams and lakes, algae and other plants have all they need (read more about the role of phosphorus in your watershed below).
- Some cities, like Minneapolis MN, have enacted ordinances limiting the use of phosphorus fertilizer in efforts to protect water quality. More information about this ordinance and a lawn fertilizer reduction experiment can be found at Lake Access.
When you buy fertilizer the package will be labeled with three numbers.The first number indicates total nitrogen (N), the second indicates phosphorus (called available phosphate (P2O5) and the third, soluble potash (K2O). Look for a middle number of zero, which indicates phosphorus free fertilizer.
3. Apply the product correctly. The following tips are taken from Responsible Fertilizer Practices for Lawns.
- Fill granular fertilizer spreaders on a hard surface where any spills can be easily cleaned up. NEVER wash off fertilizer spills into the street or other hard-surface areas where they can easily enter storm sewers and ultimately surface water areas. Wash off granular fertilizer spreaders over turfed areas to prevent runoff of fertilizer from hard surfaces. Fill and clean liquid fertilizer applicators over turfed areas for similar reasons.
- Close the gate on the fertilizer spreader when crossing hard-surface areas or go back and sweep up the material. Reuse it another time or put it back into the spreader.
- Try to use a drop spreader, which is slower but more precise than a rotary type spreader near surface water. Next to shoreline areas, apply fertilizer around the perimeter of the property with a drop spreader to create a safety zone. The rest of the area farther away from the shoreline can be fertilized with a rotary spreader. Since the perimeter has already been done with the drop spreader, it is not necessary to hug the shore because fertilizer may get into the water. The same kinds of precautions should be taken when using liquid fertilizer.
- Avoid getting fertilizer into natural drainage areas or pathways on a property. These areas may not necessarily be hard-surface areas, but they can carry fertilizer directly into the surface water before having the chance to infiltrate into the surrounding turf/soil area.
- Leave grass clippings on the lawn area to decompose and recycle nutrients back to the turf area. They should not be blown or raked into street gutters or onto sidewalks and driveways where they may be carried with runoff water to surface water. Nutrients released in water through decomposition may cause undesirable algae and vegetative growth.
- NEVER apply nitrogen fertilizers to water resources directly or to frozen ground.
How much water should I use?
- Between irrigation and rainfall, grass should get about one inch of water per week.
- Apply water only when needed; over watering can promote diseases and cause unnecessary runoff into lakes and streams.
- It’s best to water once or twice a week to promote root growth. This makes grass more drought-tolerant.
When should I water?
- Water during the coolest part of the day to reduce water lost to evaporation (4 a.m. to 8 a.m.).
- Avoid watering on rainy or windy days.
What else can I do?
- Mow grass to a height of 2 1/2 to 3 inches to reduce the amount of water lost to evaporation and promote root growth.
- Reduce the size of mowed lawn where possible and replace with natural vegetation.
- If the weather is very dry, limit foot traffic on the lawn to reduce stress put on the turf.
- Be sure that sprinklers are watering only grassy areas and are directed away from roads, driveways and sidewalks.
- Perform regular maintenance checks on nozzles and hoses to be sure there are no wasteful leaks.
Do you have some water friendly lawn tips? Share them with the UMD Office of Sustainability onFacebook, Twitter or Instagram (at @UMDSustain).
Remember to hashtag #WaterWednesday.
Note: Water Wednesday posts are written by UMD Storm Water Assistant, Charlie Johnson, who works with Facilities Management and the Office of Sustainability to help implement the UMD Storm Water Pollution Prevention Plan (SWPPP).