NATURAL Plant Cover and Soil Potentialities

The use of vegetation as an aid in forecasting the agricultural possibilities of unimproved lands originated with primitive man and was used to some extent by the early settlers in our own country. Primitive man, with plenty of land on which to locate his fields, chose only the best. He was guided in his choice largely by the natural plant growth and the wealth of accumulated experience as to the type of crop to be grown on land characterized by different types of native vegetation.  This method was also used in the older Farming sections of our own country, but without scientific study it could only be used successfully where there was accumulated experience to serve as a guide.  With our rapid migration into new and unknown territory in many cases having no agricultural history, the choice of land fell either on chance or was directed by exploiting agencies. It thus happens that in the newer settlements farms will frequently be found located on types of land least suited to crop production, or, again, equal settlements in regions of very unequal potentiality.

By a careful study of the types of natural vegetation and the type of soil and climate associated with each, and by the use of all available agricultural history, it has been possible to assign to each type of vegetation a value in terms of agricultural potentiality. Intensive studies of this kind have been made on the high plains, in the Great Basin, the Colorado Desert, and more extended but less intensive investigations in other portions of the United States. Practical application of these studies has been made by the Geological Survey in the classification of the 640-acre homesteads. Many of these homesteads, located in regions with little or no agricultural history and no climatic data, were readily classified on the basis of the natural plant cover.

One can easily estimate the relative worth of an acre of land covered with cat-tails as against an acre of oak and hickory; an acre of willows as against the same of hard maple; sagebrush as against seep weed. It is more difficult to distinguish between the value of an acre of land covered with hard maple and one of white oak, or an acre of sagebrush and one of shad scale. In the case of sagebrush and shad scale, studies have made it possible to give the two types separate values. A good, healthy, uniform stand of sagebrush indicates land well adapted to dry farming. However, dry farming on shad-scale land is not advisable, as it involves too great a risk.  Again, sagebrush land is well adapted to irrigation farming. Shadscale land, even under irrigation, requires careful handling and especially where it borders greasewood or is mixed with greasewood there is much chance of future alkali trouble.

In the southwestern deserts the lands covered with a good stand of desert sage will be farmed wherever there is water available for irrigation. gThe bulk of the best land farmed at the present time is of this type. Although creosote bush indicates land with a lower salt content, it is more often sandy or stony, not so level and less fertile, so that a smaller percentage is fit for farming.

On the other hand, lands covered with good growths of seep weed, saltbush, pickleweed or salt grass are mostly unfit for farming or hazardous at best. The high water table and the high salt content call for reclamation and for intelligent and special handling.

That the native vegetation can be used as a criterion in making estimates of the crop possibilities of land still unimproved is substantiated in comparisons of the large agricultural or nonagricultural areas of the United States with the areas of native vegetation.

The greatest block of agricultural land in the United States was that originally covered by the tall-grass prairies. As we pass westward, the tall grass gives way to short grass and there is a corresponding change in agriculture. Farms give way to ranches; with the increase in size of farms goes a decrease in land in crops and an increase in grazing land as crop production becomes less certain and the land becomes better adapted to grazing. Within the tall-grass area the type of farming is indicated to some extent by the type of vegetation.

The great Corn Belt lies in the central portion of the tall-grass area, the area characterized by bluestem sod grasses. The spring-wheat area is largely in the wheat-grass area. The best of the shortgrass lands is the grama-stipa portion lying in the Northeast, whereas the poorest, from this point of view, is the Muhlenbergia lying in the Southwest. Crops can be produced with fair certainty on grama-stipa land or grama-buffalo-grass land, but are very doubtful on Muhlenbergia land. In the Northwest the wheat-grass sod lands of Washington and Oregon are now given over largely to the production of spring wheat. The only forest area of the west which is giving way to agriculture is the cedar-hemlock forest of western Washington and Oregon.

One of the areas showing practically no agricultural development is the spruce-fir area, covering the higher altitudes of the Rocky Mountains, of the West Coast Range, and of the northeastern highlands of New York and the New England States. The spruce- tamarack area of the Great Lakes region, which has no agricultural value in its original state but is capable of reclamation, shows slight agricultural development.

Contrasted with the spruce-fir, which has no agricultural value, the cypress, tupelo, and red gum of the southern lowlands has been largely turned to agricultural land. In its original state, like the spruce-tamarack, it has no agricultural value though its capabilities after reclaiming are high.

The natural vegetation can also serve a very useful purpose in indicating the limits of the region over which any experimental data, climatic data, or agricultural history can be applied with a reasonable degree of safety. Often the results of an experiment station nearest: the local farm should not be applied, but preferably those of a station located in a region showing the same type of vegetation even though it might be more distant. It may, therefore, serve as a useful guide to agriculturists in the application of agricultural history or tge results of scientific experimentation.

If rightly understood, the natural plant cover indicates the suitability of land for crop production, either with or without irrigation, and offers an important indicator not only of the kind of crop but also of the most desirable type of culture. A large economic waste might be prevented by correctly determining the future use of land.  The natural vegetation affords a sound basis for such a determination.