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Fig. 19 Clear water Humus or top soil Heavy loam Clay Gravel Knowledge of what the soil in your grounds is like can be obtained very simply. Fill some milk bottles half full of water. Trowel into them samples of soil taken down to the two-foot level at various spots. Shake well. Let the bottles stand a day or so. Out will settle your soil's components—gravel at the bottom, then clay, then the loams, then the humus or topsoil, then a layer of clear water. {See Fig. 19.) Before any planting is done, the chemical character of your ground should be determined and adjusted. Soil chemistry is for the farmer, not the home owner, except in one important particular: the pH index. This refers to the amount of free acid (H) or alkaline (OH) molecules in the soil. At pH 7 the soil is said to be neutral. The acid scale runs down to pH o, the alkaline up to pH 14, each degree in the scale indicating a tenfold change. Most trees like slightly acid soils ranging from pH 5.5 to pH 7. Above pH 7 most trees have difficulty absorbing some of the trace minerals they need—iron, manganese, zinc, copper, boron. A few species are acid-lovers, like sourwood and yellowwood. To find out what your soil reads, get your County Agent to test it, or test it yourself with a cheap litmus kit which your drugstore will sell you, with directions for its use. If the pH of your soil reads low, raise it by spreading lime. Where it is too high, lower it with aluminum sulfate. |
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