Building a Compost Heap

Building a compost heap should be done in light shade, on level and well-drained ground. If in full sun, the pile may heat up enough to kill bacteria near the surface. Considerable heat is developed in the composting process itself. In dry regions, the pile might well be made in a shallow depression to catch rainfall, but this basin should not be so deep as to risk "drowning" the lower layer of compost.

When building a compost heap, unless the soil in the pile site is naturally high in lime, sprinkle the area with ground limestone before applying the first layer. Each successive added layer should also be sprinkled with limestone: the processes of decay generate acids which will slow up bacteria while favoring fungi. If this happens the nitrogen products left behind will be ammonia nitrogen rather than the more desirable nitrate nitrogen forms. The addition of lime favors bacteria rather than fungi.

Begin building a compost heap like a giant sandwich of 4-inch alternate layers of organic matter and soil. If your soil is very heavy, it may pay to buy extra "black dirt" for this purpose. While ordinarily I advise against buying outside soil because it almost always is full of weed seed, composting destroys these seeds so they do not become a nuisance.

Between each layer when making compost sprinkle a little chemical fertilizer. Except for fish emulsion, dried blood and urine, organic fertilizers are not desirable: they, too, must be rotted down before they become useful as fertilizers; thus they add little to the action of the pile at first. The layers can be added one at a time or the entire pile built at once - whichever the available supply of organic matter dictates. As each layer is placed, it should be wet down enough to moisten it thoroughly but not so much that it is soggy.

Time To Turn

Whether all the layers are laid down at the same time or over a period of several weeks, the entire pile should be turned over and mixed one month after it is completed. The chief benefit of this is to release any excess carbon dioxide that may have accumulated in preliminary decomposition, as well as to give bacteria additional oxygen. The pile may have to be wetted down if it looks dry after turning. Turn it over again three or four weeks later. If the pile doesn't seem to be rotting down rapidly, add more fertilizer at this time.

Building a compost heap under ideal conditions - outdoor temperatures in the 70s or above - the compost should be ready to use in about three months. In estimating when a particular lot will be done, don't count any month when air temperatures average below 50 degrees. Under such cool conditions the inside of the pile stays warm but the decomposition of the outer layers slows up.

Absolutely any organic substance can be used when making compost (the previous chapter discussed fatty, greasy and oily materials). Dead animals, bones, table wastes, lawn clippings, leaves, weeds, plants pulled from flower and vegetable gardens, hair, wood shaving and sawdust, spoiled grain, clippings from wool goods and many other organic substances are all good raw material for building a compost heap.