Tuesday, May 1, 2018

Play by the Rules when Fertilizing Your Lawn




If you live in VA, follow the rules when you are feeding your lawn!


Virginia Tech and the Commonwealth of Virginia Department of Conservation and Recreation have established restrictions on fertilizing lawns that, if followed, will provide for a nice, thick, green lawn and at the same time help protect our surface waters. Whether you fertilize the lawn yourself or hire a firm to do it for you, making sure these guidelines are followed should be on your spring to do list.

Nutrient enrichment, along with sedimentation, are the two biggest problems facing the Chesapeake Bay. Excessive amounts of nitrogen (N) and phosphorus (P) get carried off by storm water and stimulate algal blooms which deplete the water of oxygen and cause aquatic plants and animals to die.

Homeowners can help in two ways. First, if you have a lawn, maintain it! Folks who let their lawns go in the name 'helping the environment' don't! Weedy, thin stands of grass have more erosion problems and increase storm water runoff. In fact, nothing helps protect soil from erosion (limiting sedimentation), improves water infiltration (limiting run off) and cleans tainted water (filtering out unwanted chemicals) better then a nice thick stand of grass. Secondly, maintain your lawn in a responsible manner. Avoid excess use of pesticides, properly manage your lawn clippings and, most importantly, fertilize wisely.

Managing phosphorus is actually pretty easy. Since 2013, phosphorus in lawn maintenance fertilizers has been banned in the Virginia. The exception is when a soil test shows there is a need. So secure a proper sample of soil from your lawn (see our Bio Green blog post on soil testing). Submit it to Virginia Tech and follow the recommendations for applying the phosphorus your lawn needs (if any). Test the soil every 3-6 years thereafter to see if any additional phosphorus (P) is needed.

Nitrogen is a little more complicated and requires a little math. For total nitrogen applied each year to a cool season grass (most lawns in NOVA are cool season), you should not exceed 3.5 pounds of nitrogen (N) per 1,000 square feet of lawn area.

That total amount of nitrogen needs to be broken up into multiple applications timed to when the turf needs them the most and avoided when the turf is dormant and/or the ground is frozen. If you are using a slow release form of nitrogen (it will say so on the label), these individual applications can be no greater the .9 lbs/1,000 square feet. If all fast release nitrogen is used, the limit is .7 lbs/1,000 square feet.

Do not assume that the lawn care company you hired or the pre-mixed 4-step fertilizer you apply yourself follows these guidelines. Most do not. For example, the popular brandname 4-step program applies over 40%  more nitrogen then the state recommends.

If you would like to avoid the math but still make sure you are not contributing to the problem every time you feed your lawn, feel free to contact me directly at this address (click here). Let me know the fertilizer blend you or your lawn care provider will be using (list the amount of N, P and K and the percentage that is slow release or simply snap a picture of the label) and I will tell you the maximum rate at which it should be applied. If you like, we can outline a lawn feeding program for the entire year.

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