Page:Popular Science Monthly Volume 67.djvu/692

686 received at the surface all the water given them, while 2 and 4 were subirrigated by means of a three-fourth-inch glass tube which extended some three inches vertically into the soil.

These plants started all alike, and in every other respect except water-supply had an even chance, so that the difference in their development, as seen two months after the seeds were sown, is highly instructive. The thing which at once strikes the eye is the hopeless condition of the plants numbered 3, which, having had a meager supply of water, applied wholly at surface, had been left behind in the race at an early day and were now drying up. The plants numbered 4 had received exactly the same amount of water, but it was placed, by the simple method of subirrigation already described, where it would be utilized with a minimum loss by evaporation.

A comparison of numbers 1 and 2 indicates that there is no virtue in subirrigation, in itself considered. It is merely a means of preventing waste. Both of these had received a large quantity of water, the former at the surface, and the latter by way of subirrigation. As far as this experiment goes, then, it appears that aside from alkaline or other conditions requiring special treatment, which it is not the purpose of this article to discuss, water may be applied indifferently at or below the surface, if there is only enough of it. It is simply a matter of supplying the roots of the plant with all the water it requires. But if it only needs about half as much when applied in the simple way that has been described, the fact is of sufficient importance to engage the attention of horticulturists from Colorado to California. It is true that reports on the results of subirrigation, thus far, have not been encouraging in all respects, and the application of such methods on a large scale would necessarily involve a rather large initial outlay; but when one considers the great expense involved in preparing for the irrigation of an orange grove, say, in southern California, and the continual outlay of time, labor and money required by the present wasteful methods of applying water, it may well be asked whether some simple method of subirrigation may not be developed which, when once the practical difficulties have been overcome, will prove in the end more economical as regards cash outlay, and at the same time make it possible for the available water to do double duty.

It is to be borne in mind that with very few apparent exceptions, such, for example, as the areas bordering upon the lower Colorado, the arid states and territories are nowhere possessed of an unlimited watersupply; in most cases there is a fixed limit, beyond which no amount of 'development' will produce more water. If, then, by economical methods, a given quantity of water—all that can be depended upon for a certain area—can be made to irrigate satisfactorily twice as many acres as by wasteful methods, he who shows how this can best be done, and inaugurates the doing of it, will deserve well of his country.