Most of us in Hawai'i are becoming more environmentally conscious and willing to pitch in to help the environment in our own way. More of us are recycling aluminum cans, glass and plastic containers, and paper products to reduce the amount of waste going into our diminishing landfills. We are also making a greater effort to buy products made from recycled materials and energy-efficient appliances for our home. This truly is becoming the age of environmental consumerism and can have a big impact on improving our environment.

So why am I mentioning all of this when I'm supposed to be writing about your yard? Well, if you are one of the thousands of Hawai'i homeowners trying your best to maintain a healthy lawn and landscape, you're a better environmental steward than you may have thought. Even with all of Hawai'i's open green space, home landscapes with our trees, shrubs and lawns are major environmental helpers that are often overlooked.

Let's just focus on the environmental benefits of grass. The Lawn Institute of America estimates there is more than 31 million acres of managed grass in the U.S. — more than 50,000 square miles of it — and more than 60 percent of it is found in lawns like yours. One of the main benefits of a healthy lawn is in the dense leaf area and amazing root structure. The root zone (the depth of the roots in the soil) of most warm-season grasses we have in Hawai'i is about 12 to 18 inches, depending on soil type and water availability.

According to the Lawn Institute, a healthy lawn has 6 grass plants per square inch, and each individual plant produces 387 miles of roots! That means the average lawn contains 8.5 million turfgrass plants, which produce 3 billion miles of roots! Wow! Next time it rains, notice where the water that fills the gutters and storm sewers comes from. You'll see that very little comes from your lawn. That's because dense, healthy sod grass is the best natural surface we have for trapping and storing rainwater and at the same time reducing soil erosion. A healthy 10,000-square-foot lawn can absorb more than 6,000 gallons of rainwater without noticeable runoff. The root system also acts as a natural filtering system for the water, absorbing excess fertilizers and other chemicals before it reaches the ground water that is the source of our drinking water.

The leaves of those millions of grass plants also help clean our air, collecting dust and dirt and absorbing various types of harmful atmospheric gasses. One acre of grass can absorb and assimilate hundreds of pounds of sulfur dioxide created by automobile exhaust. In addition, grass and all other green plants absorb carbon dioxide and give off oxygen through the process of photosynthesis. This is one of the main processes that remove carbon dioxide, one of the main "greenhouse gases," from the air. More importantly, it is the only natural process that produces the oxygen we breathe in the air. Believe it or not, your home landscape is an important oxygen producer just by itself. A 50-foot by 50-foot area can produce enough oxygen to sustain a family of four. It is estimated that the trees and grass along the U.S. interstate highway system release enough oxygen to support 22 million people annually.

Grass is one of the major producers of new soil. Your lawn is continuously making topsoil by developing, dying off, decomposing and redeveloping. All of this adds to the organic matter in the soil. An average-size home lawn in Hawai'i can generate more than a ton of grass clippings annually. By leaving clippings on the lawn and allowing them to decay naturally, you return a significant amount of the nutrients that help it grow and avoid possible pollution of the ground water caused by excessive applications of chemical fertilizers. If you do decide to collect and dispose of clippings and other green waste, using our new green waste curbside recycling pickup can reduce the total amount of rubbish going to the landfill by up to 25 percent.

And finally, let's talk about increasing energy costs. The greenery around us is nature's air conditioner. A well-maintained lawn and landscape keeps your home significantly cooler by reducing surface temperatures by 30 to 40 degrees compared to bare soil, and 50 to 70 degrees cooler than streets and sidewalks. Don't believe it? On the next hot, sunny day go stand barefoot in your lawn for a few minutes and then see how long you can stand in the street or sidewalk. Researchers have estimated an average home landscape provides the cooling-effect equivalent to 10 tons of air conditioning, compared to the 3- to 4-ton capacity of the average air-conditioning unit.

Just as aluminum and plastic recycling helps the environment, one family can make another positive contribution by creating and properly caring for a quality lawn — not to mention adding 10 percent to 15 percent to the value of your home.

Jay Deputy is an education specialist in landscape horticulture and turf at University of Hawai'i-Manoa's Department of Tropical Plant & Soil Sciences, and state administrator for the Certified Landscape Technician Program sponsored by the Landscape Industry Council of Hawaii. Got a lawn-care question? Write to deputy@hawaii.edu or call 956-2150 during working hours.