If this process is repeated for a year or two, an amazing amount of organic matter, which finally breaks down into humus, will be added to the soil. Winter rye is particularly useful for this purpose because if sown in fall it will continue to grow every time the soil thaws in winter. After winter rye is plowed under in spring, a crop of buckwheat or vetch can be seeded, giving a double supply of green matter for sheet composting.
Do not, however, try to squeeze out too much growth the year the property is to be put into lawn or garden areas. If these areas are to be planted in spring, the winter crop of rye should be plowed under at the earliest possible date in late winter or early spring to allow for initial decomposition before seed is sown. If the lawn is to be seeded in August, plowing should be done some time in July. Be sure to apply fertilizer to the cover crop before turning it under, whether this is done in spring or in fall.
THANKS TO SYNTHETICS
The roles of lime, marl and ground limestone in flocculating clay and silt have already been mentioned. Synthetic chemical soil conditioners, introduced with such a fanfare of publicity in 1952, are disappearing from the market. But they should be mentioned because of the contribution they made in calling attention to the need for soil amendment. To no small extent, awareness of this subject may be said to stem from this publicity.
Partly because of their high cost, the products introduced are not likely to come back in their present form. But with the idea once started, who knows what combination of science and commercial enterprise may find a way to make new forms of such materials practical and economical?
Another method of improving soils is to add minerals which increase porosity by mechanically opening soils to air and water. One of the oldest materials used for this purpose, a favorite with British gardeners, is ordinary sand. The addition of enough sand to a stiff clay soil should, in theory, separate the particles so that air and moisture can move in freely and thus "correct" the soil so it will crumble readily when squeezed into a ball. Sand should also provide pore spaces in which bacteria and fungi can thrive. This in turn would gradually improve the humus content so that a clay soil would turn into a clay loam. Unfortunately, this end is not always reached when sand is added to clay.