Humus, Composts and Mulches
How You Can Produce Humus
An easy old-time method of increasing soil organic content was to grow ryegrass or soybeans, and then plow them under as a green manure. You can do this in between harvests if you grow a winter cover crop. Much the same effect can be obtained by mixing purchased organic materials--such as peat--into the soil. But avoid introducing weed seeds. This will be a hazard if you obtain manure from a local barnlot. There may be weed seeds in the hay, or even in piles of sawdust left to rot at the mills.
Such organics yield humus when they decompose, but they should be mostly decomposed when
you use them. If organic materials high in carbohydrate (such as sawdust or straw) are
mixed fresh into soil, a temporary imbalance of fertility results until decay has
progressed. The little organisms which cause rotting compete with garden plants for
nitrogen. If you are mixing incompletely decomposed organics into your soil, you should
add at least a pound of actual nitrogen to each 1,000 square feet or your plants may
starve at the very time you think you are helping to nourish them.
Many gardeners prefer to have a compost pile where they dump weeds, fallen autumn leaves,
and grass clippings, and allow them to decompose into humus. Practically anything that was
once alive can be added, including garbage from the kitchen such as non-meat table scraps,
egg cartons, paper towels, eggshells, coffee grounds, shredded paper from the office, etc.
Various techniques are used, but the main objective is to encourage the microorganisms to
attack the organics. These little organisms need moisture and air in order to flourish. So
a compost heap should be arranged to drain adequately, but it should be dished out at the
top to trap water rather than shed it. In some instances, purchased bacteria or earthworms
are added, but usually nature supplies these adequately.