Fertilization services can strengthen turf roots by providing them with the nutrients they need.

But concerns about runoff, watershed contamination and soil health have made some question this sometimes-automatic practice. Evaluating what products you use and how you use them is always smart business.

1. Test the soil

When’s the last time you ran a soil test on a client’s property? If you’re like most contractors, it was a long time ago or never. Soil testing can give you a clear picture of the nutrients turfgrass needs to thrive. Running tests will help you avoid runoff and leaching. It can also save you money by requiring less product.

As you probably know, the three main nutrients needed for optimum plant health are nitrogen (N), phosphorus (P) and potassium (K). Secondary nutrients (sulfur, calcium and magnesium) are needed in smaller amounts for normal plant growth. Micronutrients are also needed, but in even smaller quantities.

Plants need all of these for optimum health, but many are readily available in the soil, air and even rainwater and snow. Some might not be available because of soil pH, which should be on the top of your list for testing. For example, in arid climates, a high soil pH ties up iron, which leads to yellowing leaves. All the nitrogen in the world won’t green up an iron-starved turf.

Like most plants, turfgrass uses nitrogen more than any other nutrient to grow sturdy roots, stems and leaves. In many parts of the country, there is plenty of phosphorus in the soil. Other soils may be rich in potassium. Plus, if you have been fertilizing regularly for several years, some nutrients can actually build up, and nitrogen might be all you need to apply. But you won’t know until you test the soil.

“A thorough soil analysis is recommended for best results on all landscape sites,” says David Diehl, manager at Gro-Power fertilizer in Chino, California. “We offer a commercial soil analysis with interpretation and recommendations. We include texture, organic matter, estimated nitrogen release, phosphorus, potassium, magnesium, calcium, soil pH, hydrogen, cation exchange capacity, percent base saturation, soluble salts, excess lime rate, sodium and boron.”

Independent soil laboratories are available in every part of the country, and many manufacturers and distributors offer services as well. In addition, check with your local cooperative extension or colleges and universities with agriculture and/or horticulture programs for this service.

2. Read the label

Sounds simple, but somehow this important step gets overlooked. All fertilizers will have three numbers indicating the N-P-K. So if your soil doesn’t need phosphorus, be sure that the middle number reads “zero.”

The label will also tell you if the fertilizer is quick-release, slow-release or both. Quick-release fertilizers contain high rates of nitrogen and should be applied carefully. Too much nitrogen can burn turfgrass. Plus, nitrogen moves quickly through the soil. If the turfgrass does not absorb applied quick-release nitrogen, it will simply leach away, possibly contaminating watersheds, streams and lakes.

Different turf types require different rates. In general, cool-season grasses, such as Kentucky bluegrass, fine fescue, tall fescue and perennial ryegrass, require 2.5 to 3 pounds of N per 1,000 square feet per year, while warm-season grasses, such as bahiagrass and bermudagrass require 5 to 10 pounds of N per 1,000 square feet per year. The application rate needs to be adjusted depending on your fertilization frequency.

3. Calibrate your equipment

Fertilizer spreaders should be calibrated before use and periodically throughout the season. It’s a simple procedure. The amount of fertilizer to cover a specific area (usually 100 or 1,000 square feet, since that is how fertilizer application rates are measured) is weighed out and applied, and then results are noted. Detailed calibration instructions are available from manufacturers or online at many sites, including Penn State at plantscience.psu.edu/research/centers/turf/extension/factshedts/calibrating-spreader.

If you are using a broadcast spreader and fertilizer lands on sidewalks or streets, be sure to sweep it up. Otherwise, it will run off and become a contaminant. Any materials that are applied to a property should remain on the property.

4. Use proper rates

Be sure to follow label rates to avoid runoff and leaching. In fact, it will generally do no harm to use less than the label rate—never use more.

The Global Soil Survey, a program for golf course superintendents by Pace Turf, is dedicated to determining the minimum amount of fertilizer needed to maintain healthy turf, and has found that rates can be dialed back to astonishingly low levels. For example, Superintendent Jason Haines (www.turfhacker.com) cut fertilizer costs from more than $12,000 to about $2,000 a year by using the lowest rates possible at Pender Harbour Golf Club in British Columbia.

5. Consider organics and compost

Organic fertilizers and compost are naturally slow-release and, used properly, can greatly reduce runoff and leaching. Plus, compost actually improves the soil, which can lead to less fertilizer and pesticide use down the line.

You can make your own compost using materials that would normally go to the landfill with relative ease. Or you can purchase finished compost in most areas of the country.

“If you are purchasing compost, make sure that it is from a reputable source and that it is mature, nutritionally well balanced and does not contain heavy metals, pathogens or other toxic substances,” says Robert Morris, consultant with ViraGrow in Las Vegas, Nevada. “It should be dark brown when moist. You should not be able to discern or see any of the products used to make the compost. Leaves and stems should not be discernible. It should be screened so that larger materials have been filtered out.”

Fertilizers laced with compost, humic acids, amino acids and other soil-beneficial substances can also shrink your ecological footprint. Humus-based fertilizers and soil conditioner products contain humus, humic acids and beneficial soil bacteria, Diehl says. “These increase the soil’s fertility by adding high-quality organic matter and beneficial microorganisms back into the soil,” he explains.

6. Watch the water

Be sure to water in fertilizer thoroughly after application if rain isn’t predicted. If heavy rains are on tap, delay applications, as too much rain can lead to runoff and leaching.

If the soil is soaked and soggy, delay applications until it dries out a bit. Working on saturated soils can lead to compaction, which will in turn lead to runoff. For safety’s sake, skip fertilization within 25 feet of any bodies of water.

7. Record your results

Keeping detailed records of application rates, timing and materials will help you plan for the future and save both guesswork and money. If you are experimenting with lower rates, note the results. If your lawns are still looking terrific with a lower rate, you might try dropping it a bit lower next time. If you are trying a new product, keeping detailed records can help you compare results and costs.

Fertilization is a service that can ensure your clients’ lawns stay green, as well as keep your bottom line in the black. By taking a few simple steps, you can also be confident that your practices are green as well.