Page:Popular Science Monthly Volume 75.djvu/216

212 methods of sewage disposal. No treachery to the land can be so great as that which sends out into the sea the highly concentrated nitrogenous products which have with toil been wrung from a soil which is becoming poor in capacity for crops. In this primitive riddance of valuable matter we accomplish a further loss by polluting the waters and if we do not thus endanger human life, we destroy the fields in which a certain important amount of aquatic food can be produced.

A further gain can be had on soils already in use by expert management in the direction of proper succession of crops and a thoroughness of occupation and tillage often seen in Italy, France or Belgium, but only exceptionally found as yet in our own land. We need not only better directed labor, but more labor on the same soil. In the regions of sufficient rainfall, which comprise nearly the eastern half of the United States, we shall find, or did find in 1900, seven men per average square mile, tilling the soil, or one to each lot of 91.4 acres. Making generous allowance for ground not in tillage, we still find the working force far too small to bring maximum quantities of food out of the ground. We need also on much plow land and meadow east of the arid belt supplementary irrigation for many seasons and for some crops, and with abundant water resources, there is no good reason why nature should not thus be helped to her best. Some areas, many, it would doubtless be better to say, would be doubled in productive worth by more effective drainage than has yet been applied. The barest inspection of crop averages per acre, or of half the ripening harvests that fall under the eye of the traveler, supports the belief that a vast increment of food can be won from lands that are not now given a full chance.

Further inquiry leads us to lands not now cultivated, which might and will be made productive. Here some of our largest reserves appear. Lands of an arid or semi-arid character embrace about two fifths of our territory. In these great fields, and in small patches now improved, crops can not be expected unless water is applied by man. There is doubtless force in the claim that these soils are potentially marked by exceptional richness, due not only to the fact that they are virgin soils as related to man, but because they have not suffered the leaching and waste of important elements which have affected soils in lands of large rainfall. It is cited by Hilgard that Nile lands have for centuries supported an average population of more than one and one half persons per square acre, which means a density of about 1,000 per square mile. Without questioning the accuracy of this claim, it may be urged that we do not know whether flooding by the Cordilleran irrigator would be as favorable to fertility as the flooding of the Nile. Nor may we forget comparative standards of living any more than in the case of China.

We must also keep in sight the inevitable condition that there is water enough in the west to make fertile but a small fraction of the dry area. If we accept this at one fifteenth and receive without discount