WASHINGTON — New Year's resolutions are opportunities to do something you have always wanted to do, often for self-improvement. In the spirit of the season, here are some that will help you improve the environment, too.

Resolve to:

• Recycle. A mature tree will produce just 14 newspapers. The energy saved by recycling one aluminum container will run a television for three hours. Recycling one glass bottle will save enough energy to light a 100-watt bulb for four hours.

• Cut air-conditioning use by planting trees around your house. One estimate is that three mature trees around a house can cut air-conditioning needs by 10 to 50 percent. If 100 million trees were planted around homes and businesses, the nonprofit conservation group American Forests estimates, $4 billion would be saved in energy costs. Planting trees anywhere will also help remove carbon dioxide from the atmosphere, helping to offset the damage from burning fossil fuels.

• Help trees establish a balance with their growing medium. Drastic changes to the root system of a tree will severely stunt its growth or kill it. Don't change the grade over roots of trees, not even by one inch, and don't drive over roots with tractors or trucks. Just one time can crush enough absorption roots to hinder a tree's ability to renew.

• Save mature trees. They remove particulate pollution and, according to the U.S. Department of Agriculture, increase property value. Trees can boost a property 's value 10 percent to 20 percent, depending on the siting and variety, the government says. The U.S. Forest Service estimates that in 50 years, one tree generates $30,000 in oxygen, recycles $35,000 in water and removes $60,000 worth of air pollution.

• Consider the soil's needs before planting. One of the most difficult ingredients to retain in soil is organic material. In a natural world, trees drop leaves. Smaller plants, grasses and wildflowers die, providing stems and leaves that decay and leave a rich layer of humus. Most plants depend on humus, or compost-rich soil, for air, moisture and nutrients. The Friends of the National Zoo reports that we discard 24 million tons of leaves and grass annually. Compost your landscape debris.

• Replenish the mantle of topsoil with compost. It takes about 1,000 years for nature to make just an inch with the precisely right mix of minerals and organic materials. But we can make that in a day. Test your soil pH and correct as needed for more acid or alkaline conditions. Amend earth with three to four inches of compost on the surface, and more dug into the top 10 to 12 inches of soil. Lay two inches of compost over trees' root systems, and let gravity do the rest.

• Consider every plant's longevity. Install trees far enough apart that they can mature into specimens in 12 to 15 years. Encourage healthy biodiversity.

• Use less pesticide. Start with safe alternatives, and use the more toxic material only if absolutely necessary.

• Design native plants into gardens. Indigenous wildlife depends on them for food and shelter.

• Ensure that plant roots get oxygen, from air space in earth that has been deeply dug and amended with compost, facilitating drainage and air circulation. Install plants in moist, well-drained soil. Drought-tolerant plants must have well-drained, moist but not soggy conditions. Plants will suffocate in perpetually wet soil.

• Conserve natural resources. Use drip irrigation for trees, shrubs and flowers. For lawns, a low spray in early morning on a day without wind is best. Collect rain and the water from your dehumidifier for indoor and outdoor plants. Irrigate with bath and dishwashing water as long as there are no phosphates in it.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md.

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