IN THE GARDEN SPRING IS THE TIME FOR COMPOST-PILE CONSTRUCTION.

Byline: JOSHUA SISKIN

Even though it's only May, we are about to head into our extended warm season, and it makes sense to think about mulching and composting at this time. By adding compost to the soil when planting, and by applying mulch to the soil surface, watering can be reduced.

Decomposition of organic matter in the soil is nature's way of protecting plants from desiccation. The end product of this decomposition is humus, which consists of skeletons of microbes.

Humus is sweet-smelling and fluffy, dark brown in color, appearing to be the richest earth imaginable, even though, strictly speaking, it is nothing but the remnants of living organisms.

Humus has the peculiar ability to both hold water and allow it to drain through, as if it consisted of millions of microscopic sponges.

When you build a compost pile, you will have two types of material soon enough: rough or moderately decomposed organic material and completely decomposed material or humus. Speedy composting depends on keeping the pile moist and aerated since decomposing bacteria require moisture and oxygen to thrive. Therefore, you will want to keep a hose and a pitchfork or spading fork close to your pile - the hose for moisture and the fork to keep it loose and aerated.

One of the companies responsible for recycling the green waste we put at the side of the curb is Agromin, in Ventura. Since Agromin composts 20,000 tons of our lawn and garden clippings and trimmings each month, it might be instructive to follow their guidelines for composting. Keep in mind that the word compost means mixture, and refers to the approximately 50/50 ratio of green/brown or nitrogen/carbon materials that are mixed together in a well-constructed compost pile.

According to Agromin, green material should consist of grass clippings, fresh garden trimmings, weeds, coffee grounds, and kitchen scraps (primarily fruit and vegetable cores and peels). Brown material should consist of dry leaves, straw, twigs, sawdust and wood chips.

Excessive green material will create a pile that can become slimy and foul smelling, while too much brown material will break down slowly. Don't include the following in your compost pile: weeds with seeds, ivy, Bermuda grass or perennial weeds, plants treated with herbicides, manure from meat-eating animals (dogs and cats), meats, fats, oils, dairy products, charcoal ash. You can build a container to store your compost, purchase one, or just make a pile on open ground. A compost pile should not exceed 4 feet in height or width so that air can circulate.

When creating a pile, start with a thick layer of coarse material at the bottom (such as twigs or straw) so that air can move freely inside of the pile. Then, alternate even layers of green and brown materials and mix them together. When you have the proper combination and there is adequate moisture and oxygen available, the pile will heat up considerably, a sign of active microbial life and decomposition.

A successful compost pile will heat up to a minimum of 140 degrees. The pile should be watered and forked through at least once a week. If you are diligent in these practices, you will see humus form in two to three months. Meanwhile, you can remove rough compost for mulch.

In addition to saving water as soil amendment and mulch, compost reduces supplemental fertilization and retards soil erosion.

Responding to last week's column on synthetic grass, Duane Ruth, who installs SYNlawn (www.synlawn.com), defended his product by pointing out its wide use, aesthetic appeal and improvement over earlier types of synthetic grass. SYNlawn has been installed on the grounds of several Las Vegas hotels, as well as in virtually every Southern California community. He took issue with the word ``artificial'' as a negative quality, citing the use of rock and other types of mulch that are no more lifelike than his nylon grass.

TIP OF THE WEEK: To prepare a lawn for summer, punch holes in it with an aerator, available at most rental equipment yards. The next time you mow, the cores of soil unearthed by the aerator can be picked up with the grass and thrown on the compost pile. Aeration opens up your lawn so that roots can more easily put out new growth and water and fertilizer can be more readily absorbed. A thin layer of aged compost or Nitrohumus over the top of an aerated lawn provides a nice finishing touch.