What is a “green” lawn?

“Geist residents need to stop using fertilizer” was the opening salvo on local news broadcast following last Friday’s community meeting to inform homeowners about the toxic levels of blue green algae in Geist Reservoir.

Actually, what was said by Dr. Lenore Tedesco, director of the Center for Earth and Environmental Science at IUPUI, was, “Everyone has a responsibility to be very, very conservative with fertilizer use.”

There’s a big difference in these two statements.

So how do you separate fact from fiction? Can you have a positive impact on this problem and still have a great looking lawn? Well, that depends on who you ask.

I asked several local and national lawn service companies and garden supply retailers about their fertilizers and services—and I got many different answers (more on that later). The answers were analogous to: “That depends on what the definition of ‘is’ is.”

Lawn fertilizer doesn’t just fertilize lawns.
Lawn fertilizer, especially when applied incorrectly, fertilizes a lot more than just your lawn. Excess nutrients are carried by runoff into ponds and lakes. The same nutrients that help grass grow also help algae and pond weeds grow, leading to algae blooms and excessive aquatic plants that are not only unpleasant to look at and to swim in, but also affect food quality, habitat for fish and other organisms—and can become toxic.

Does this mean environmentally aware citizens are doomed to have unattractive lawns? No. By being informed and following a few simple recommendations, you can make sure that your lawn looks great and you’re not contributing excess nutrients to our water supply.

According to the Agricultural Extension websites of several universities (Texas, Minnesota and Purdue), most lawn and turf fertilizers contain phosphorous, which is rich in the nutrient that cause algae to grow. Understanding the compounds in the fertilizers you use is essential. Chemical and organic fertilizers show their nutrient content with three bold numbers on the package: N-P-K. These numbers represent three different compounds: Nitrogen, Phosphorous and Potash (Potassium). The three numbers listed on fertilizer labels correspond to the percentage of these materials found in the fertilizer. When looking at both chemical and organic fertilizer labels, you’ll notice that the NPK numbers don’t add up to 100 percent.

So, what is the rest of your fertilizer made up of? That depends on the fertilizer.

Chemical fertilizers can have any number of additional ingredients including dirt, sand and even materials that are potentially hazardous to your health and to the environment. Organic fertilizers primarily consists of, well, pulverized chicken poop.

What does each nutrient do? In addition to other properties, nitrogen helps plant foliage to grow strong. Phosphorous helps roots and flowers grow and develop. Potassium (Potash) is important for overall plant health. Yet phosphorus (the P) is an essential nutrient that is already contained in every living grass plant cell, and the amount of phosphorus generally needed by the grass plant is significantly less than nitrogen or potassium.

Okay, so what can I do?
Many garden and lawn care professionals say that little to no additional potassium and phosphorus are needed in our soils, as these elements are present already. However, they say we need to liberate these elements with proper soil aeration, soil drainage, beneficial soil organisms, etc.

What this means is that if you properly aerate the soil, earthworms, beneficial microbes, and other critters found underneath your lawn will have better access to the oxygen they need to thrive. As they live and digest organic matter, they help to create soil that is healthy and fertile. Proper watering of your lawn is essential as well. Healthy soil is the backbone of a healthy lawn.

For the average homeowner, this means that chemical or organic fertilizers with NPK labels that show low numbers or even zero for potassium and phosphorus are perfectly adequate for your lawn and garden as long as you’re properly caring for your soil.

And the thing about fertilizers is that without proper soil aeration, mineral nutrients and other factors, your plants may not be able to absorb phosphorous and potassium anyway. So loading up your soil with high levels of phosphorous and potassium may not make much difference with the health of your lawn.

“Once a lawn is established, phosphorus in fertilizer isn’t generally needed,” according to Josh Halstead, marketing manager for Indianapolis-based LawnPride. “Most homeowners don’t aerate enough. If you employed a twice-a-year aeration schedule, over-seeded with grass seed and properly watered your lawn, you could actually limit the amount of fertilizing treatments.”

A local representative of TruGreen Chemlawn, the nation’s largest lawn care company, indicated that the products they currently use in their lawn care service applications are manufactured by Purdue University, but they generally contain the same active ingredients as found in products sold at retail garden and hardware stores.

Home Depot has a special section of their website known as ECO Options. Its claim is that it is designed to educate and inform consumers about “reducing negative environmental impacts every day.” The site offers advice, online clinics, videos and more. One of the relevant products found there is the Vigoro brand of lawn care products. Vigoro’s Ultra-Turf Phos Free product category offers consumers an environmentally friendly choice with several zero phosphate fertilizers, weed and insect controls, and winterizers that are specially formulated for lawns near lakes and streams. Moreover, their garden center manager was knowledgeable and enthusiastic about stocking these products to meet those needs.

Representatives at the local Lowe’s, Menards and Ace Hardware stores were not as informative, nor were their websites. Many of their associates weren’t even aware of the local blue-green algae problems at Geist. All said they do not stock any fertilizers that were phosphorus-free.

And while Dr. Tedesco urged a long-term watershed management plan to reduce the amount of fertilizer that runs into the lake when it rains, she stated: “If you don’t start now, it is only going to get worse,” adding that we may not see the positive results of our efforts for five to 10 years.

However we can change our behavior today. I’m not a scientist nor do I live on Geist Reservoir, but I’m going to change the way I treat my lawn. Heck, I might even save a little money and get some exercise. Besides, after this summer, my lawn needs a fresh start anyway.

So is your lawn “green” or is it green? With a little knowledge, a few informed decisions, and little bit of effort, it can be both.