STEP 2 Soil pH Testing

Tips on how to get your soil pH right for growing grass

We all want our lawns to have the best chance to thrive, yet it is very common for homeowners to skip the basic step of testing their soil's pH (the measure of how acidic or alkaline your soil is). Growing turf when the soil pH is far from the optimum will make it much more difficult for your lawn to use nutrients and establish robustness.

All plants have an optimum pH, for turf grasses, they grow best in slightly acidic conditions. Generally, most Long Island soils are too acidic and therefore require lime to be added to amend the soil for optimum turf health. However there is no way to know how much lime to add if you don't test your soil first.

The optimum pH for turf grass is from 6.0 to 6.5. If you have Kentucky bluegrass it is more important that your lawn be kept within that range. Tall fescue is more tolerant of a slightly wider span of pH levels, but also grows best in that optimum range.

A pH of 7.0 is neutral, distilled water for example is 7.0. Lower pH numbers indicate acidity and higher numbers alkalinity. The scale is not linear, each point on the scale indicates a factor of ten, so a pH of 5.5 is ten times more acidic than a pH of 6.5 and pH of 4.5 is 100 times more acidic than 6.5.

STEP 4: Soil pH TestingAll lawns will be healthier with the proper pH, but getting the pH near optimum is even more important for organic lawns. With organic lawns the goal is to establish a healthy turf ecosystem that only needs minimal inputs and which prevents most problems before they occur. For those who use chemical pesticides and quick release synthetic fertilizers, they will rely upon those chemicals to kill or suppress the weeds and other problems that are caused by the underlying unhealthy soil conditions. With organic lawn care, the approach is to prevent those problems from occurring by first establishing the healthy conditions for the turf.

Experienced organic landscapers consider getting the soil pH in the optimum range a key factor to growing a healthy organic lawn.

Acidic soil will make the nutrients in the fertilizer you apply less available to plants. At a pH level of 5.5, as much as one third of the fertilizer you apply will be wasted. Soil that is too acidic will affect the color of the turf, causing a yellow, wilted looking grass. Acidic soil is also associated with thin and bare patches in the turf, and is ideal for going weeds such as crabgrass, moss and plantain. If your turf shows these conditions, they could be indicators of soil that is too acidic.

Certain plants that are often grown near lawns prefer acidic soil, such as pine, spruce and fir trees, oaks, and rhododendrons. These plants both like acidic soil, and they will also make your soil more acidic as they drop leaves and needles, therefore, they can present challenges for a lawn if these trees hang over it.

You can buy pH test kits in garden centers and hardware stores and home centers across Long Island. They are inexpensive (about $13) and seemingly not hard to use. However, these tests can be a bit finicky and hard to interpret if you are not experienced in using them. Follow instructions carefully and be sure to use distilled water. Tap water can alter the results of the test. There are also inexpensive meters available that provide a digital readout, but they have gotten bad reviews for being unreliable. The best choice may be to take your soil sample to either a good garden center that provides tests, or drop it off or mail it to a Cornell Cooperative Extension location.
 
If your lawn's soil pH is below 6.0, you should add lime to raise it. Follow the instructions on the bag, based on the result of your pH test. You should target a pH of no higher than 6.5.

Lime is available in different forms and types. Pelletized lime is less dusty and easier to handle and apply than pulverized lime. Lime is generally slow acting; it can take a few months for it to fully affect the soil's pH. Dolomitic lime will add both calcium and magnesium to your soil. Calcitic lime adds calcium, but not magnesium. Most soils on Long Island are not deficient in magnesium, so unless detailed soil testing shows a lack of magnesium, calcitic lime is usually the better choice for Long Island.

The calcium in lime, will discourage the growth of dandelions. Improving the soil pH with lime not only sets the conditions for the turf to fill in better and prevent crabgrass, by also providing calcium, it helps to reduce the appearance of dandelions.

Since much of Long Island soil is highly acidic, you may not be applying enough lime for optimum growth and color for your lawn. The difference between 5.0-5.5 and 5.6-6.0 pH for a lawn is approximately double the amount of lime needed to amend the soil to get it to the optimum pH for a lawn. According to Rutgers, "if soil acidity is not corrected before establishment, deep root extension and development of grasses will be inhibited...prone to water stress...and require frequent watering". Additionally, nitrogen uptake by lawn grasses is dramatically impacted by the acidity of soil. (Managing Soil pH for Turfgrasses)

For pH testing and recommendations for the application rate of lime, you can mail or drop off a sample of your soil directly to Cornell Cooperative Extension of Suffolk in Riverhead (Extension Education Center at 423 Griffing Avenue, Riverhead). You can also drop off a sample at the Bayard Cutting Arboretum, where samples are transported to Riverhead once a week (Bayard Cutting Arboretum at Montauk Highway, Oakdale). Results can be conveniently delivered by mail or email. Whenever collecting soil for testing, be sure to follow all procedures outlined by the diagnostic lab. (Soil Testing Laboratory Information).

If you would like a more comprehensive test of your soil, that includes items such as the levels of organic matter and nutrients in your soil, along with Cornell recommendations, you can send a sample to AgroOne (http://dairyone.com/analytical-services/agronomy-services/soil-testing/). The cost is from $7 to $17, depending on the tests requested.

Soil Tests Available Online:

Where to get your soil tested:

  • Atlantic Nursery, Freeport
  • Chick's Southold Agway, Southold
  • Martin Viette Nursery, East Norwich
  • Olsens Garden Center, Nesconset
  • Hicks Nurseries, Westbury
  • Abby's Parkside, Wantagh
  • Stable's Garden Center, East Moriches

Long Island Organic Landscapers
Although it's easy for the average homeowner to maintain their lawn organically, some may too busy and wish to hire a professional. In that case there are thousands of landscapers on Long Island to choose from, but only a small but growing number of experts who can maintain your lawn and landscape without the use of chemical pesticides. They can be found here.

To see all the previous steps in the series, please visit 12 Steps to an Organic Lawn 

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