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Is Your Yard Chemically Dependent?

by Lisa Dahlbacka

This article originally appeared in the July 1992 issue of the Wellspring newsletter, published by the MTU Regional Groundwater Education in Michigan (GEM) Center, now the Center for Science and Environmental Outreach at Michigan Technological University.

Summer is here, and people want their lawns to be green and weed free, and their gardens to produce large, healthy vegetables. Pesticides, which include herbicides, insecticides, fungicides, and rodenticides, are quick and easy to use for successful results but may be hazardous. Not only do they kill their target, they can also harm or kill other things, even humans. Publications of state and federal agencies caution that such chemicals may contaminate surface and groundwater supplies. Chemical fertilizers, although not meant to kill anything, sometimes contaminate water with nitrates.

Why organic?

"Organic" means derived from plants or animals. Organic gardening enhances the biological relationships among plants, pests, and predators in the garden, rather than disrupting them. It minimizes the use of fertilizers and pesticides, especially man-made ones. However, do not assume that "natural" or "organic" pesticides are necessarily safer than inorganic ones. According to the Michigan State Cooperative Extension Service, the plant-derived pesticide rotenone is more poisonous than many common man-made pesticides, such as malathion and Sevin. Caring for your lawn or garden without chemicals takes more effort. However, many people find the benefits to the environment and to their health, in terms of exposure to fewer chemicals, makes the added effort worthwhile.

The U.S. Department of Agriculture (1980) has found that, in some cases, organically grown plants are higher in quality and yield than chemically grown plants. These improvements, which may take several years to appear, depend largely on the type of crop and seasonal weather patterns.

Nip weeds in the bud!

Hand picking is the safest way to control weeds. Pull or hoe weeds early, before they flower (and reproduce). A sheet of plastic or garden fabric can be placed over a garden in the autumn to prevent weed seeds from germinating in the soil. Bark or rock areas can be lined with black plastic or other weed barriers. Herbicides with ammonium sulfamate or magnesium chloride are less toxic than most others, if you must use chemicals to control weeds.

Raise your gardenís defenses against pests

Healthy plants require healthy soil, and a good sign of rich, fertile soil is the presence of earthworms. You can fertilize your garden organically by using compost recycled from vegetable food waste, grass clippings, and ripped up leaves. Do not include diseased plants and weeds with seeds, as these items cause problems in your garden. Meat, bones, or fat, which attract rats and mice, should be left out. Compost can be created in a 20-gallon galvanized garbage can with a layer of gravel and soil in the bottom. Holes poked in the bottom and sides allow water to drain and air to circulate. Simply cover each new layer of waste with soil, keep it damp, but not saturated, and turn it occasionally. Turning is easily done by shoveling the material into an identical but empty can.

If you want to balance the pH of your soil or adjust the concentration of nutrients, such as phosphorus, potassium, or nitrogen, you can buy organic amendments from your local greenhouse. These additives are mixed in certain concentrations according to the needs of your soil. Common soil amendments include peat moss, manure, seaweed, blood meal, bone meal, and fish meal.

Garden crops should be rotated each season to keep pests from building up in the soil. Because mineral requirements vary by crop type, rotation also allows the soil to regain a balance in fertility.

Good companions

Crop plants may grow better with certain "companion" plants surrounding them. Two major benefits that a crop plant may receive from a companion plant are nutrients lacking in the crop plant, and protection from certain insect pests. For example, beans and peas release nitrogen into the soil, which is deficient in most other plants. Garlic and other members of the onion family produce a strong chemical that many pests canít stand, but their companion plants can! However, what may be a "companion" to one crop plant may be an "antagonist" to another. The table below shows some companions and antagonists of common garden crops grown in the U.P.

Companion insects that prey on most pest insectsóbut not on garden plantsóinclude ladybugs, damsel flies, assassin bugs, and harvestmen (daddy-longlegs). These helpful insects are killed easily with commercial pesticides. Hand picking pests like earwigs and grasshoppers is often the only way to control them without using pesticides. Some crops, such as potatoes, cabbage, cauliflower, broccoli, and lettuce, are best left unplanted if you don't want to hand pick pests or use chemicals. Crawling pests such as cabbage loopers ("inch worms"), army worms, slugs, and snails can be kept away from tomato plants and seedlings by partially burying a coffee can or other metal sleeve around the plant. Copper sleeves are effective against slugs and snails because their body slime reacts with the metal. Paper or cardboard sleeves are also effective barriers against creeping pests. A mild soap and water solution sprayed on garden plants washes insects off of plants and repels them for a while. Cheesecloth draped over seedlings keeps insects from chewing on them.

Send that bluegrass back to Kentucky!

Choosing a breed of hardy, disease- and pest-resistant grass that is compatible for U.P. climate and soil types reduces dependence on chemicals to keep lawns alive. Kentucky bluegrass may be the best-known variety of grass, but it is not particularly well suited to our area. Local greenhouses recommend a blend of fescues and ryegrasses for lawns in the U.P. Blends work better than individual grass types at covering all areas of a lawn, but they come only in seed form.

Sod is better at holding any lawn chemicals that are used. It also prevents soil erosion. The Meyer Z-52 zoysia hybrid, available only as sod or plugs, resists drought, disease, insects, and sub-zero temperatures (Gerard, 1991).

Grass can be kept healthy by mowing often and cutting no more than the top third of the grass blades. Grass clippings left on the lawn decompose quickly and act as natural fertilizer.

Organic gardening is a great way to have a productive garden or weed-free lawn without the risk of polluting surface water or groundwater with pesticides and chemical fertilizers.

Most of this article was adapted from:

Dalquist, D.; L. Dahlbacka; S. Manial; B. Pietz. 1991. Organic Gardening in the U.P. Made Easy! Project for Scientific/Technical Writing, MTU, 12 pp. Other references: Flynn, A.A. and R.E. Kessler. 1990. A Consumer Guide to Safer Alternatives for Household Hazardous Products. Hazardous Waste Management Program, Office of Toxics and Solid Waste Management, Department of Planning and Development, Santa Clara County, California.

Gerard, Claude. 1991. Non-toxic, weed-free lawns are not the impossible dream. Lawn and Garden, vol. 35.

Naegele, E.C., J.L. Taylor, and J. Cloutier. Organic Gardening. Extension Bulletin E-824 (25). Cooperative Extension Service, Michigan State University, Department of Horticulture.

Olson, K.M. 1991. Lawn chemicals and fertilizers. Lawn and Garden, vol.35.

Rudd, K. and P. Engelking. 1988. Urban agrichemical use: itís not just the farmerís problem. Journal of Freshwater, vol. 11.