Watershed Notes

Janet Baldwin
Odessa

The Impact of Lawn Care on Water Quality

Over the past few months we have introduced the Appoquinimink Tributary Action Team and defined its purpose as studying the problems affecting water quality within our watershed and suggesting strategies for correcting those problems. Courts have mandated that the presence of certain nutrients be reduced within our watershed so that we are within the Total Maximum Daily Load (TMDL) that streams can handle and still maintain reasonable water quality. The first two nutrients that have been targeted for reductions are Nitrogen and Phosphorus, which are primary ingredients in lawn fertilizer. As the weather begins to warm, our thoughts turn to spring and how we can make sure our lawns look green, well cared for, and certainly free of pesky weeds. Some of the practices that we rely on to get those desired results can have a significantly negative impact on the quality of water in our watershed. Most of us don't think of adding the chemicals that we apply to our lawn directly to the water that we drink, but the end result may be just that.

What happens when we apply fertilizer to our lawns?

For most of us, the chores associated with home and yard maintenance, are compressed into precious few weekend hours and as a result we are always looking for ways of getting "the job done" quickly and with the least amount of pain and effort! We find ourselves at our favorite home supply store on Saturday morning trying to quickly pick up a bag of fertilizer/weed killer that will do everything to give us a perfect lawn with the least amount of effort in the shortest amount of time. Usually we think the higher the percentages of Nitrogen and Phosphorus, the quicker the results will come. And of course we will not have to reapply because our lawn will have everything it needs in one application! What we fail to realize is that following this line of thinking can lead to disastrous results in regards to our water quality.

Phosphorus is a nutrient that supports plant growth but that includes the growth algae and weeds in our lakes and ponds. If there is an over-abundance of algae, it depletes the oxygen supply in the water, which will injure or even kill fish. Nitrogen assists rapid growth in plants but it is soluble and not held by soil particles. That means that the nitrogen that is not taken up by plants will travel downwards and may enter the ground water supply. Excess nitrate in our ground water supply can pose a serious health risk. It is particularly dangerous for infants under six months of age who because of immature digestive systems, convert nitrate to nitrite which inhibits the blood's ability to carry enough oxygen. In addition, the groundwater eventually enters the surface water, contributing to its nutrient content.

When fertilizer is applied, there may be some that falls on the sidewalk, driveway or street. When it rains, the fertilizer is carried directly into streams and rivers effecting water quality. Also, if the fertilizer you use has more nutrients than the plants need, the excess nutrients enter the groundwater and follow the flow of the water table. These nutrients eventually find their way into the well water that we drink. With the concentration of people living in our area, the total accumulative effect can cause significant impairment to water quality.

What can a homeowner do to protect water quality?

The first step to take is to have your soil tested to determine your need for fertilizers. Soil testing is a service provided by the Delaware Cooperative Extension / New Castle County office at the University of Delaware. Soil test kits can be ordered by mail from:

Delaware Cooperative Extension / New Castle County Office
910 S. Chapel St.
Newark, DE 19716-1303
(302) 831-2667

The cost for a kit ordered by mail is $8.50 and checks should be made payable to the University of Delaware. If you stop by the Cooperative Extension Office to pick up your kit, the cost is $7.50. Their office is located on Rt. 72 across from the old Caldor store. They are also offer a workshop titled "I Hate my Lawn." Also you can obtain non-biased, science based information from Master Gardener volunteers by calling the Garden Line at (302) 831-8862 or online at garden-line@udel.edu.

Basic tips for a healthier lawn that will not release excessive nutrients into surface or ground water are:

• Fertilize only in the fall. Fertilizing in the spring pushes top growth at the expense of root growth. The roots system does not develop enough to support growth in the summer yielding very poor results.

• Grow turf type tall fescue grasses, which are pest resistant.

• Mow high.

• Don't bag clippings. Clippings can provide much of the nitrogen needed for plant growth.

• Don't water in the summer (allow your grass to go dormant).

• Plant new lawns in the fall.

Once you have had your soil test done, you will receive information specific to needs. This will help you choose the right course of action that will produce the results you are looking for, reduce your mowing and maintenance requirements, and protect our waters.

If you are interested in joining the Appoquinimink Tributary Action Team, please click here to ask for more information or contact Kathy Bunting-Howarth at (302) 739-4590.