Roots and Shoots: Healthy Soil = Healthy Grass

And that means less environmental lawn-care damage

By Pamela Doan

Once again, reach for the soil test before the bag of chemicals when it comes to fertilizing lawns. The optimal pH for grass is 6.0-7.0, similar to many vegetables and flowers. If your lawn is above or below that level, the grass has a harder time getting the nutrients it needs from the soil.

Take soil samples from several areas for large lawns to get the best results. Free pH soil tests are available at the Master Gardener Plant Sale on Saturday, May 17, in Brewster. Otherwise, for a modest $10 fee, soil samples can be taken to the Cornell Cooperative Extension Office in Putnam County. They’ll recommend the proper amount of lime that can be applied to your lawn if the pH is less than 6.0.

If a soil test comes back with a perfect mid-range 6.5 pH level, but you’re dissatisfied with its appearance, first identify problem areas. Is the grass stunted? Discolored? Are there patches where it doesn’t grow well?

Low maintenance lawn practices leave time for appreciating a hammock on a summer day. (Photo by P. Doan)

Low maintenance lawn practices leave time for appreciating a hammock on a summer day. (Photo by P. Doan)

Many factors affect turf grass health and appearance. Fertilizer isn’t necessarily the answer, though. Disease, insects, and weather conditions like ice, frost, snow and drought are all possibilities that cause grass to look poorly. Other conditions like shade, high-traffic, compacted soil, weeds, and burning from salt or other chemicals also impact a lawn’s appearance and should be evaluated separately. The only thing that fertilizer changes is a nutrient deficiency. (After listing these possible lawn problems, I do wonder why bother trying to maintain a lawn at all.)

Some signs of lacking nutrients are clear. If the lawn needs nitrogen, the grass has a yellow cast and the grass looks thin. Too little phosphorus in the lawn can present as dark green to purplish color leaf blades in established grass. A potassium deficiency appears as yellowing and browning of older grass. Again, the only method to define this for certain is to further test the soil, however. Visual signs are only a clue that nutrients might be the underlying problem and indicate further testing is warranted. If the pH test comes up in the right range, but the lawn has characteristics of nutrient deficiencies, test for that next.

Organic options for adjusting the nutrients in the soil are available at landscape centers and big box stores, as well as online. The ratio of nutrients is represented on the bag as N for nitrogen, P for phosphorus and K for potassium.

Due to the many environmental problems caused by lawn fertilizers, New York issued new regulations in 2010. In brief, phosphorus application is forbidden on home lawns unless a soil test indicates it is necessary; fertilizer can’t be applied to lawns between Dec. 1 to April 1; and fertilizer use is restricted within 20 feet of a waterway. Additionally, any fertilizer that is spilled on a hard surface must be cleaned up to prevent runoff. Many counties have other restrictions, but I’m not aware of others in Putnam.

Organic fertilizers should be applied with just as much care as synthetic options. Everything has a consequence and too much is not better. Following the package instructions is essential. The main point here is to improve the soil, which will lead to better looking grass, in theory. The qualifier here is that only if you’ve managed other problems affecting the lawn, like disease, insects, etc.

Feather meal is a common ingredient in organic lawn fertilizers. It’s a source of nitrogen and usually that’s the main nutrient that could be lacking. A bag might use the designation 8-0-0, which means it contains 8 parts nitrogen, 0 phosphorus and 0 potassium. N-P-K is the corresponding designation for decoding commercial fertilizer bags.

Seaweed is a source of potassium and bone meal is a source of phosphorus. Even though it’s organic material, not synthetic, the same rules cover applications. Milorganite is made from wastewater solids and while many gardeners won’t use it on vegetables, it’s another source of nitrogen for lawns. It’s regulated by the Environmental Protection Agency for safety. I found a good list of organic materials online with their N-P-K values and recommended application levels.

Creating a sustainable lawn that uses fewer resources and requires little maintenance starts with creating healthy soil and builds on that base with turf grass varieties appropriate for the particular landscape’s conditions, usage, and climate. Consider native grasses and even reducing the size of a lawn for easy maintenance and less environmental consequences.


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