Compost is often touted in the gardening books as an excellent soil amendment with all kinds of wonderful benefits, and much of that publicity is true. What is not noted is that compost is already decomposed organic matter and so to use compost as a mulch, you may be giving the plants some minor nutrients and growth activators, but you are not feeding the earthworms and the soil microbes.
Another problem is that compost is seldom available in large quantities from the home based compost bin, because most of us don’t make compost at home. You can buy bags of compost at the garden center, but when you need a bunch, the price becomes an obstacle.
So while compost is not really a good source of organic content for your soil, it still offers many benefits. We use compost when we are planting or transplanting plants; it helps the plant adjust to its new home with less stress. We mix compost with our potting mixes in outdoor containers. We include compost, when we have it, with any organic materials we use to amend soil that is being dug or worked up for a new bed.
If you wish to make your own compost there are complete instructions in the file Composting
Here are a number of sources of compost that are often free.
Because so many states have passed legislation prohibiting yard waste from landfills, many communities across America are setting up municipal based or county based leaf composting operations. Leaves are still collected by the community trash pickup system as before, but instead of taking the leaves to the landfill, those leaves go to a community composting site. In most cases, they are laid out in huge windrows hundreds of yards long. Large machines, designed to turn compost, move down the windrows every few days turning the pile to get more oxygen into the decomposition process. Usually by June or July, the leaf compost is finished and ready to distribute.
Much of this valuable compost is used on public areas including parks, athletic fields, and landscaped areas around public buildings. The professional nursery industry also takes a lot of this compost, since the cost is usually reasonable. In most cases, there is still compost left over for use by residents in the community. Many community composting systems offer compost to residents free for pickup in plastic bags, pails and trucks.
Community leaf compost is excellent compost and if it is available to you, include it in your landscape maintenance plans. Your own compost bin will conveniently handle your own leaves and any yard waste that is not accepted at the community composting site, but this virtually unlimited municipal supply provides all the extra you might need.
Municipal Composted Sludge
Another very serious waste disposal problem in North America is sewage, the liquid effluent from industry and the toilets of private residences. Again, composting has come to the rescue and promises to solve the sewage disposal problems of many cities across the continent. By early 1991, 133 cities in the United States and Canada had undertaken a program to compost sludge, the solid residue from liquid waste into a dark, rich, humus that is ideal for use in residential landscapes. In the coming years many more cities will be instituting similar programs.
When the liquefied waste arrives at the sewage treatment facility, the water is removed leaving a rather odiforous damp material called "sludge cake". This sludge cake is then mixed with wood chips and composted for about 30 days. Then the larger wood chips are screened out and the remaining material is composted further for another 30 days. The final composted sludge is sifted once more and is then ready to use. By this time it has only a mild odor which disappears within two days of application on the soil. This procedure varies somewhat from city to city, but the basic approach is pretty uniform across the country.
For many years, this composted sludge was not considered safe for use in home applications because of the concern about the occasional high concentration of heavy metals that might prove toxic if used in home settings. In most cases, that problem has been solved and the heavy metal content of most composted sludges is quite safe for all home uses. People may wish to avoid using it on vegetable gardens just to be absolutely sure, but in most cities the heavy metal content of their composted sludge is well below safe tolerances for all home applications.
Municipal composted sludge is sometimes sold through retail outlets such as garden centers and nurseries. Most of the communities that produce it allow residents to have as much composted sludge as they can haul away for no fee at all. This is a marvelous opportunity for getting a very high quality soil amendment costing only the time it takes you to pick it up and take it home. You should check to see if a city near you has such a program.
Composted sludge tends to have a higher organic content than compost made in the home compost bin. Consequently, its value lasts several years longer than normal homemade compost. If you spread municipal composted sludge about 1/2 inch thick over your lawn, you will get benefits of that application for 2 to 3 years. If you have a new home sitting on subsoil because the contractor took away the layer of topsoil, municipal composted sludge is the perfect antidote to the problem. A few truckfuls of sludge will turn subsoil into topsoil and will support all kinds of plants extremely well.
Some folks in certain areas of North America have access to another excellent source of humus and that is composted mushroom soil. Mushrooms are grown in composting straw and manure. After the composting process is over, the material is no longer any good for growing mushrooms. This ``spent'' mushroom soil is an excellent soil conditioner and is usually sold by mushroom farmers at a very reasonable price. Let the mushroom soil age for at least six weeks before using it in your garden, because the manure may not be sufficiently aged to be safe for the food crops. If mushroom soil is put through a shredder with homemade compost or with peat moss, it makes a wonderful, soft, uniform material that can be used anywhere on the landscape.
There is no doubt that compost offers a multitude of benefits to residential yards and gardens. The next best thing to mother nature's own humus, it is indispensable as a soil conditioner, plant fertilizer supplement, and plant protector. Compost made in the backyard has the added virtues of being both environmentally sensible as a method to recycle yard waste and spare diminishing landfill space, and of being virtually free, after you build your bin. There is also another benefit to be found in compost, that is the benefit it offers to the person who is engaged in producing it and using it. The investment in energy and time that results in a valuable product, the satisfaction of accomplishing physical work and enjoying the outdoors through the seasons, the feelings of satisfaction about returning something to the earth rather than just taking from it--these things are not easily measured. However, they are nonetheless important benefits.