Friday, August 16, 2002
An all-weather strategy for coping with suburban drought
Conventional lawn care can be the single most environmentally damaging thing many suburban homeowners do, and in most cases, less is more. That is, less water, less fertilizer and less pesticide use is healthier for us and for the environment (especially our ponds, streams and rivers). There is an alternative system of lawn care that uses a more healthful approach to produce better looking turf without severe environmental damage: organic lawn care.
What's this, you might ask. We want to look at the stuff, not eat it. And although you could eat organically grown grass, it wouldn't be very nutritious. But at least it wouldn't poison you or the environment.
Think back to grade school geography, when you learned about the Great Plains. Remember the thousands of square miles of lush grasslands where the buffalo roamed? Guess what? Nobody fertilized or watered them, and the plains states get much less rainfall than New England.
Organic lawn care takes lessons from nature. One of the things that distinguishes the natural grasslands of the plains from most New England yards is incredibly rich soil. The soil is many feet deep and full of life: insects, worms, nematodes and fungi. It sucks up and holds moisture like a sponge. So grass roots grow very deep as much as one to two feet and have an endless supply of nutrients. They can draw on the water stored in the sponge-like soil for many weeks between rains. Organic lawn care, therefore, has one major focus: build up the soil.
Unfortunately, housing developers tend to finish their work by spreading only a few inches of topsoil on the new yard, just enough to get grass started and let it grow until the house is sold. It falls to the homeowner to build the soil up to the proper depth of 6 to 8 inches minimum more is better. This can be done by buying large quantities of topsoil and starting a new lawn from scratch, or by spreading compost on the existing lawn in 1/4 to 1/2 inch thick layers in spring and fall. Over several years the compost will mix with the existing soil and deepen it. The process is accelerated by aerating the lawn first making holes that the compost can fill and rental machines are available for this purpose. After these initial few years of investment, the homeowner has a lawn that will not only look good, but pretty much take care of itself.
The second lesson from the Great Plains pertains to species of grasses. The traditional grass used in northern lawns is Kentucky Bluegrass. It needs more water and more fertilizer than any other species, and is especially susceptible to heat and drought. So why is it used? It is the only grass that forms sod. This allows developers to lay a lawn down like a blanket, and instantly call the job done. The homeowner pays the price for this expediency in the form of endless maintenance. What grows on the Plains are naturally occurring grasses, adatpted to their environment, not Kentucky Bluegrass. In the last few years a species called Tall Fescue has been developed which seems especially successful in this area when combined with several other species. It's important to use a mixture so that the species most adapted to a particular spot will take it over.
A third lesson from the Great Plains addresses pesticides. Nobody was there to use any, and as a result, nothing killed the rich soup-of-life in the soil. As a result of that, no one species of pest got out of balance. Suburban homeowners often obsess about chinch bugs and other beetle larva, and spread poisons willy-nilly to kill these supposed horrors. But they often wind up killing much of the other life in the soil that would naturally eat the beetle eggs and limit the problem. There are organic insecticides that can be used as a last resort (milky spore disease and beneficial nematodes), but usually the best solution to apply is benign neglect. Most of the time, the small number of grass-eating larva in the soil will simply not do enough damage to be noticeable. Weeds can be discouraged by use of a natural, pre-emergent herbicide called corn gluten in the early spring. But remember, healthy thick grass will naturally crowd out weeds.
A fourth lesson from the Plains regards mowing. The higher the grass leaves are allowed to grow, the deeper the grass roots will grow, and the stronger the plant will be. While no one wants a 10-foot-high lawn, most suburban lawns are mowed much too short. Three inches should be the minimum, and as much as four inches is even better. The roots grow roughly twice as deep as the leaves are tall, so three- to four-inch cutting height means six- to eight-inch roots, just enough to use the soil depth you should have established. In contrast, if you try to make your lawn look like a putting green and cut it to a half inch, the resulting one-inch roots will be hard pressed to find any water or nutrients, unless given artificial life-support in the form of constant watering and fertilizing. By the way, when you mow your grass high, leave the clippings on the grass. They decompose and act as natural fertilizer.
Finally, regarding fertilizer: the buffalo manure that naturally fertilized the plains grass is no longer readily available. You can replace it with organic fertilizer purchased from the garden shop around Labor Day. An annual appilcation of pure organic fertilizer is plenty not once a month, and forget the four-step plans.
Tom Sciacca is a member of the Sudbury, Assabet, and Concord Wild and Scenic River Stewardship Council
© 2002 The Carlisle Mosquito