The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Small Home Landscaping

To improve porosity, spread any one of the gritty materials obtainable over the surface to a thickness of one to three inches; the amount will depend upon how heavy the soil is. Dig, plow or otherwise incorporate this with the upper twelve inches. If sand is the only material you can get, see that it is coarse; fine sand on a heavy soil will make it more binding than before.

Gritty materials like the above will last almost indefinitely in the soil. But they add nothing whatever as fertilizer or food materials. Their action, though valuable, is purely mechanical. These fertilizer foods are supplied by several forms of organic matter as they are reduced to humus and by fertilizers themselves. Now it is quite possible, by the use of gritty materials combined with any of the fertilizers to be discussed, to grow plants without the aid of humus but you will find that the latter maintains the soil in better balance and result in better growth of plants. The ideal way to handle a heavy soil in order to gain the maximum from it is to combine gritty materials, organic matter and fertilizers. Organic matter and fertilizers are all you require for the maintenance of the sandy or lighter soils. Organic matter must be applied periodically. This does not last in the soil. It undergoes constant change until it finally disappears somewhat like feeding a fire.

The most valuable materials, from the standpoint of plant nutrition, are animal manures, well-made compost, green manures and vegetable wastes. These rot down very readily in the soil much faster in a sandy soil because of its open structure, more slowly in a heavy soil. Leaf mold (decayed leaves) or half-rotted leaves come next. But peat moss, sawdust and the commercial forms of humus contain little or no fertilizer whatever. Their action in the soil is much like the gritty materials, quite mechanical. Also they rot down very slowly. But they have an excellent effect on promoting root growth. For this alone they are valuable. In addition to supplying food materials, organic matter helps soil condition, increases the ability of a light soil to hold on to moisture and increases the efficiency in the use of fertilizer. Organic matter stimulates the soil organisms, bacteria and other microscopic life within the soil, without which there is no fertility.

So far, we have been concerned with the topsoil or that layer on the surface. Depending on the particular soil, the top layer may be a few inches deep or—as in the case of some farm soils—several feet deep. Normally, in most of our gardens, it runs between six to twelve inches. In this case, there would be little use improving the topsoil without improving the subsoil, that layer beneath the topsoil. Deep-rooting plants penetrate through the subsoil. If this is not improved, roots either cannot penetrate it or, if they do, are mostly starved.