Composting is like cooking in that the ingredients selected for its composition determine its quality. Dedicated Rosarians are always on the hunt for the highest quality soil amendments for their prized darlings, so it follows that compost brewed with nutrient-rich materials is a most desirable commodity.

Anyone can purchase products labeled "compost" at the local garden center. But, what is it made of? Will it give your soil the vital nutrients needed to feed your roses? Time is one commodity that no one can purchase, so it is important to give your soil all the help you can in order to optimize rose growth and development. If you spend precious time working an average- to low-quality compost into your soil and your roses receive only minimal nutrients, they will not develop to their fullest potential. Translation: Fewer rewards at the Rose Show. Therefore, making compost in your own back yard ensures control of both ingredients and quality.

But what exactly is compost and how is it made? Compost is the end product produced by aerobic decomposition of biodegradable organic matter, such as leaves, grass clippings, animal manure, cardboard, and the like. It contains minerals and valuable trace elements. Properly made, compost is a dark, crumbly, rich, soil-like matter with the wonderful, lung-filling smell of a forest floor.

So, where to start? Four ingredients are necessary for composting: carbon, nitrogen, oxygen, and water. Common examples of carbon include leaves, sawdust, wood chips, straw or hay, paper, and cardboard (soy-based inks are optimum). Items high in nitrogen include grass clippings, vegetable matter, urine, animal manure, and coffee grounds (some coffee places have packaged coffee grounds for the taking). Generally speaking, use equal amounts of carbon and nitrogen, by volume (a bushel of lawn clippings to a bushel of shredded leaves). The beginning composter can start with building a small pile (about 3' x 3' x 3' is a good size) in a corner of the yard. A bin or enclosure is useful to keep all the elements tidily together but is not really necessary. A compost pile does not need to be in the sun, either. It can be built in the shadiest part of the yard, and Nature can be depended on to do her work of breaking down the organic materials into this wonderful soil amendment.

Start the pile on well-dampened ground with a 4-5-inch layer of carbon, such as shredded leaves, which have been wet to the consistency of a wrung-out sponge. If the leaves are not completely wet, there will be dry spots in the compost pile, which will result in patches of whitish dry rot. A reliable method of wetting the leaves is to dunk them in a tub of water and toss them by the handfuls on the ground until the pile is the desired size and shape. This "dunk and chunk" method ensures even moisture that is not excessive. Also, it is not necessary to shred the leaves, however, the smaller the pieces the quicker they will break down into compost.

The next layer is 4-5 inches of nitrogen, such as grass clippings, which also must be wetted, see above. Alternate layers of carbon and nitrogen to make the compost pile. Using this method, the materials will break down into compost without any further human effort, although they will decompose more quickly if the pile is turned with a pitchfork ever so often and more water is added.

So, how does this seemingly magical process of turning old leaves, sawdust, and turnip parings into a fantastic soil amendment work? Why, due to the activities of bacteria and other microorganisms, which eat and decompose this organic matter, generating heat as they do so. The hottest part of your compost heap will be the center, which should heat up to about 140 degrees, hot enough to kill most pathogens and weed seeds, burn your hand, and bake a potato. (Wrap the potato in foil and stick it in the center of the pile for a couple of hours. Talk about saving energy.)

Home composters must AVOID using any manure from dogs, cats, or other meat-eating animals, used cat box litter; grease or greasy food leftovers; meat scraps, or egg or dairy products, although crushed eggshells may be used. These substances will emit unpleasant odors as they decompose, attract vermin to your compost heap, and will not decompose at the same swift rate as the carbon and nitrogen sources suggested above. Further, with regard to the carnivore droppings, a home compost heap may not become hot enough to kill the pathogens and bacteria, thus running the risk of contaminating your soil with parasites or disease organisms that can be transmitted to humans.

Some common problems with a home compost pile include unpleasant odors or the compost not getting hot and breaking down. The unpleasant odor is caused by too much nitrogen, such as too much fresh, damp grass clumped together. The solution is to add carbon, such as shredded paper, sawdust or wood chips, dry leaves or straw evenly throughout the pile. This will balance the carbon-nitrogen ratio and eliminate the bad smell. If your pile stays cold and does not seem to be breaking down, the carbon ratio is too high. The solution is to add more nitrogen, such as grass clippings, vegetable scraps, or vegetarian animal manure, evenly throughout the pile, which will balance the carbon-nitrogen ratio, heat the pile up, and kick-start your process again.

Some common vegetarian animal manures include the by-products of horses, dairy cows, steers, pigs, sheep, goats, llamas, rabbits, and poultry. These manures work just fine in a compost pile and are rich in nutrients. Studies have shown that 75 to 90 percent of the plant nutrients fed to animals will be found in their manure, so it should be no surprise that compost made from this substance is an excellent soil amendment. Solid animal manure should be mixed 1:2 with carbon, such as dry leaves, straw, sawdust, etc., unless the manure is already mixed with about 1/3 animal bedding. This mixture is adequate for composting without adding any more carbon.

Here's the scoop on poop, along with approximate nutrient ratios:* Horse manure, at .70, .30, .60, provides both nitrogen and carbon but is low in phosphorus. Dairy cow manure, at .25, .15, .25, has low nutrient numbers, which makes it so versatile as either a soil amendment or top dressing. Steer manure, at .70, .30, .40, is high in nitrogen but may contain high salt content and weed seeds. Pig manure, at .60, .50, .40, has an unpleasant smell and may not be the best choice for the backyard composter. Sheep manure , at .70, .30, .90, is dry and very rich, especially if the sheep is fed hay and grain. Goat manure, at .70, .30, .60, is high in nitrogen and other nutrients to help build soil. Llama manure, at 1.7, .69, .66, is lower in organic matter content than manures of cows, horses, and sheep, but is very high in nitrogen. Rabbit manure, at 2.4, 1.4, .60, is higher in nitrogen than some poultry manures and contains a large amount of phosphorus, which aids in the formation of flowers. Poultry manure, at 1.1, .80, .50, is loaded with nitrogen, but has little carbon.

Studies have shown that on average, two pounds of raw material (manure plus a carbon source) will yield one pound of cured compost. So ... with this information, you can see that do-it-yourself compost can provide a healthy, plentiful, and cheap source of nutrients for your rosebushes. And if you know and trust your manure source, you can be confident that your rosebushes are receiving the best you can provide for them.

*Sources: Royale's All-New Encyclopedia of Organic Gardening, An Illustrated Guide to Organic Gardening, by Sunset Publishing; Royale Guide to Composting; Ecochem's Internet article, "Manure is an Excellent Fertilizer"; and High Desert Organic Gardener's Internet article, "Llama Manure Benefits."