Composting is the mark of a knowledgeable gardener, for it is an invaluable source of the vital humus that builds Gardener's Loam.
Anything organic can be added to a compost heap, and only a very few rules govern its operation. But composting waste is the best way to get one of the very best soil conditioners - whether used on top of or in the ground. And when it is entirely free, it is sheer folly to let it go to waste.
The compost pile or heap is the time-honored place for all organic refuse, the real gardener's source of humus for incorporation into the soil. The important thing to remember about composting waste is that it is a biological process, one that involves bacteria, fungi and other soil organisms. These organisms require food to do their work, which means you must supply the same elements that are needed by higher plants.
The one difference is that these organisms do not have chlorophyll and are not able to manufacture their own energy foods such as sugars and starches. They draw upon the organic matter for these foods, but in doing so use up large amounts of nitrogen, some phosphorus and potash and small amounts of other elements. For this reason, the application of fertilizers to the compost pile will allow the organisms to work at their best, provided temperatures are favorable for their growth and the pile is moist, without being so wet that air is excluded.
Any form of organic matter that will decay is suitable for composting. Some materials, such as peat moss, spent mushroom manure, spent hops and well-rotted manure, are already partially broken down. These can be applied directly to the soil. However, if a substance contains no cellulose, fiber or lignin, it will not produce humus.
Dried blood, perhaps the most valuable of organic fertilizers, is all but worthless as a source of humus, since it contains practically no fibrous material. Urine, a valuable source of nitrogen, urea and other fertilizer elements, is another organic substance which produces little or no humus. Fish emulsion fertilizer is another non-fibrous organic material that leaves very little residue for humus formation. This does not mean they are worthless: on the contrary these three materials are among the most valuable foods for the bacteria that work on compost. A little of any one of these will start the pile or get it working again whenever it begins to slow up.
Building a Compost Heap - the how to of building a compost
Compost Activators - get your composting off to a quick start
Composting Organic Waste - types of organic waste you can compost
Other Soil Conditioners:-
Sand and Soil - sand is a popular way to condition soil, but use enough
Plant Vermiculite - an effective if less popular alternative