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EAP Publication - 68
by Dr. Stuart Hill, Director and Barbara Walsh, Research Associate Ecological Agriculture Project
More and more people are wondering whether there is a way to have a lush lawn without chemicals (Rubin,1989). That is, without the sort of chemicals that one is confronted with in the garden centre or on a lawn care contract - chemicals like 2-4-D, a suspected carcinogen (Rainer and French, 1985), and Diazinon, which has been implicated to massive bird kills on golf courses (Tattersall,1991). Links have even been found with the level of pesticide use in the home and garden and the risk of children in that home developing leukaemia (Lowengart,l987). Don't panic, a healthy green lawn without chemicals is attainable. However, taking an ecological approach does require a little more work: the setting of realistic weed tolerance levels, diligent routine maintenance, and regular pest monitoring (Envir. Can., 1991a).
The most important element of this approach is to become familiar with your lawn and with your real needs. Set tolerance levels for weeds in accordance with the lawn's intended use. Some weeds can be beneficial, particularly white clover, which can fix nitrogen from the atmosphere and make it available to the grass. Even dandelion, with its long tap root, will aerate the soil and accumulate trace minerals, and its flowers, in addition to being attractive, will provide food for minute parasitic wasps that will control pests in the rest of the garden. Weeds also provide important information about soil conditions including pH, drainage, compaction, and trace mineral deficiencies (EAP). Remember, one person's weed is another's prized flower or ground cover. In fact, you might consider other mixed species ground covers as alternatives to the problematic grass monoculture.
A properly maintained lawn is less susceptible to weeds, insects, and diseases. Pest problems will decrease over the years as you improve the biological activity in your soil (by adding organic fertilizers), and as you develop an ecological maintenance regime. The following items are often part of a routine lawn care system.
Thatch is an undecomposed layer of roots and stems that accumulates at the soil surface. It prevents water and top dressed nutrients from reaching the soil. If this condition exists, it may indicate acid soil. Thatch can be removed, preferably in the fall, with a dethatching rake, and the pH can be corrected with lime (1 lb. for each 0.1 pH below the optimal pH of 6.5 for every 100 sq.ft. of lawn).
Soil compaction from heavy "traffic" reduces the pore spaces between the soil particles. This impedes drainage and prevents the roots of the plant from "breathing". A manual or power "coring tool" can be used to remove a small core of soil, which will allow the air to penetrate. This step should be followed by overseeding and a top dressing of sieved organic fertilizer.
This is the process of introducing competitive grass species that will grow in the openings created by dethatching and aerating. It is best done in the fall when conditions are cool and moist. A mixture of locally adaptable, competitive seed varieties, sieved compost, and sand can be broadcast over the lawn. Finally, the seeded area should be raked and well watered to insure proper seed germination. The use of a net or other device to repel birds will also be helpful.
Ecological lawn maintenance relies on slow release organic and crushed rock fertilizers and avoids the highly soluble synthetic formulations. Bags with numbers on them like 20-10-20 are likely to include the latter, whereas those with lower numbers such as 1-3-2 are more likely to be based on organic materials. Commercial services often use liquefied or powered seaweed, fish meal, animal manures, blood meal and compost (Beaubaire, 1992). If you really want to be "organic", do not be misled by commercial services that argue that their urea is "organic". It is not. It is synthesized artificially, using fossil fuels, and is a highly soluble source of nitrogen that may make the grass more attractive to certain pests. If you really want to be ecological, make your own fertilizer by establishing a compost heap (EAP). Fertilizing is an area where you can have some fun experimenting. Try different amendments on different parks of the lawn and, based on what happens, select the best treatment for your lawn. Remember, however, that the faster the grass grows, the more often you have to cut it!
Improper mowing is a common cause of weed and pest problems. Mowing height should be seasonally adjusted to minimize stressing the grass. During the summer months, the recommended height is 7.5 cm, to enable the grass to continue to shade out the weeds and protect the soil. In the spring and fall, cut the grass a little shorter (no shorter than 3.5 cm) to stimulate root growth. Because grass clippings provide a valuable source of nutrients, especially nitrogen, leave them on the ground. If they are not too long, they will soon disappear. Grass cuttings that are too long will contribute to the thatch layer and should be raked up and composted.
Shallow, frequent watering causes poor root growth and increases nutrient leaching. Deep, infrequent watering, on the other hand, will promote deep root growth. Water in the early morning to allow the lawn to dry before the evening. Excessive moisture during the night may encourage fungal growth.
A pest problem is a sure sign that something needs to be corrected in the system of lawn management. The key is to identify the cause and correct the problem. Emergency pest problems, such as a chinch bug or grass grub outbreak, can be treated safely (EAP; Envir. Can., 1991b). Avoid highly toxic, persistent, synthetic materials and choose natural products that break down quickly and are least toxic. The key is not to rush from one curative solution to another but to manage the lawn in such a way that it is not attractive to pests. A few insects should be tolerated because a world in which insects cannot survive is also one in which we cannot survive.
This season set realistic objectives and follow a routine maintenance plan based on the above suggestions. Monitor and evaluate your lawn for early warning signs of problems. Correct any unfavourable condition using an ecological strategy. Inform yourself rather than relying on a chemical salesperson. Once sound workable practices have been implemented, share them with your neighbours, thereby helping to provide a more natural, healthy, and less toxic neighbourhood. Happy gardening!
Beaubaire. N. 1992. "A buyer' guide to fertilizes." Fine Gardening, 23:34-37.
EAP publications that cover composting. woods as indicators, ecological pest control and lawn maintenance may be obtained by sending a self-addressed stamped envelope to Ecological Agriculture Project, Box 191, Macdonald Campus, 21 1111 Lakeshore, Ste-Anne-de-Bellevue, Quebec H9X-IC0.
Envir. Can. 1991a and b. "Green solutions fact-sheet-lawn care and lawn disorders." Environment Canada, Communications Branch, Quebec.
Lowengart, R.A. et al 1987. "Childhood leokeamia and parents occupational and home exposure." JNCI, 79(1):39-46.
Rainer, E.M. and French, C.T. 1985. Pesticides in Contract Lawn Maintenance. Rachel Carson Council, Chevy Chase, MD. 15pp
Rubin, C. 1989. How To Get Your Lawn and Garden Off Drugs. Friends of the Earth, Ottawa, Ontario. 97pp.
Tatersall, A. 1991. "How many dead birds are enough? Cancellation of diazinon's uses on golf courses" J. Post. Reform, 11(3):15-16,
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