American agriculture is peculiarly soil destructive. Three of our greatest money crops—corn, cotton and tobacco—require that the earth shall, throughout the summer, be loose and even furrowed with the cultivator, which prepares the ground for washing away, and by its furrow starts the gully. The second factor in this peculiarly destructive agriculture is the fact of our emphasis of rainfall in summer. Third in the list of factors of destruction is the rainfall unit, the thunder shower, which dumps water, hundreds of tons per hour on every hillside acre. A little examination of the facts and careful inclusion of the time element will show that the old-world saying, "After man the desert" is quite as true in the United States as in Europe and Asia, where it has been so fearfully proven in the seats of ancient empire.
This soil resource destruction from erosion leads to the destruction of other valuable resources. We appear to be upon the eve of an epoch of waterway construction and experiment. The greatest injury to waterways is channel filling by down-washed mud. Pittsburgh has been praised highly for the energetic action of her Chamber of Commerce and citizens in appropriating money for the careful survey of drainage basins above the river, with the idea of obtaining knowledge preparatory to the building of reservoirs to check floods. They have forty-three reservoir sites, and the early construction of nineteen of these reservoirs is recommended.
A part of the reservoir plan, however, is that the land above it shall not be cultivated; otherwise the erosion from the tilled fields will promptly fill up the reservoirs, as the present condition of many eastern mill dams so emphatically attests. The carrying out, therefore, of the Pittsburgh reservoir plan necessitates the exodus of hundreds of thousands of farmers and the restriction of many farming communities to forest or a new type of agriculture.
We cannot spare all this land from tillage. But fortunately, there are other ways of using it. Land east of the 100th meridian may be divided into three classes: First, which in the absence of better estimate covers one third of the area, is hopeless for agriculture because of hills and rocks. This is mostly now in rather poor forests. The second class, also covering one third—by the same estimate—has been cleared for agriculture, but is so hilly and eroded as to be in a low state of fertility and production. The third class, the remaining third of the land, is suited to the plow and should be plowed and cultivated much more intensively than it now is.
For the first and second classes of land we need a new type of agriculture, the crop-yielding trees. Our agriculture, which depends so largely now upon those members of the grass family which we call grains, is the result of accident, not the result of science. At the dawn of history man had practically all of these small grains, which have probably resulted from the selection and seed saving of the primitive woman, as the race came up from savagery into agriculture. This primitive woman in selecting plants for her garden and little field, did not pick out the best of nature, or the most productive, or the ultimately most promising; she picked annuals because they gave the quickest return. And man has left alone and practically unimproved for all these thousands of years nearly all the great engines of nature, the crop-yielding trees, such as the walnut, hickory, pecan, acorn yielding oak, chestnut, beech, pinenut, hazel, honey locust, mesquite, screw bean, carob, mulberry, persimmon, paw-paw, etc., because their slow growth has deterred us from any attempts at improving them. We have depended upon and greatly improved the quick growing grains, which spend most of their short life in putting up a frame work which promptly perishes; whereas the tree endures like a manufacturing plant. Further than this, most of the grains have a period of crisis, during which they must receive water or the harvest is almost a failure. Thus corn must within a short period receive moisture, or it is too late to produce even husks.
Yet trees are the great engines of nature. The mazzard cherry tree, growing wild throughout the southeastern United States, often yields twenty bushels of fruit. Fifty bushels and upwards are often obtained from the mature apple trees. The walnut yields its bushels, the persimmon breaks with fruit.
Europe shows us an agriculture making considerable use of crop-yielding trees other than the ordinary fruits. Mr. C. F. Cook, of the Department of Agriculture, is the authority for the statement that Mediterranean agriculture began on the basis of tree crops, and there are now about twenty-five such crops in the Mediterranean basin. The oak tree furnishes five, cork bark, an ink producing gall which enters into the manufacture of all our ink, the Valonia, or tannin-yielding acorn, which is an important export from the Balkan states; the truffle worth several million dollars to France; and lastly the acorn. In the Balaeric Isles, I am informed, certain acorns are more prized than chestnuts and the trees yielding them are grafted like apples, and the porker is turned out to make his living picking up acorns where they fall, and enriching his diet with a special kind of fig grown in the same way for his use. We Americans are too industrious; we insist upon putting a pig in a pen and then waiting upon him. The pistachio, the walnut, the filbert and the chestnut are all important tree crops in parts of the Mediterranean countries and many American travelers have probably seen the chestnut orchards of France and Italy, which I have found by examination are able to make the rough and unplowable mountain-side, bristling with rocks, as valuable as the level black prairies of Illinois.
The natural objection may be raised that the utilization of so much hilly land in fruit and nut-yielding trees will give such supplies of new food that people will refuse to use them. The above objection is well founded; but swine, sheep and poultry eat what is given them. I have an example of a farmer of Louisiana, who planted a hillside to mulberry trees. The mulberries held the ground in place by their roots and dropped their black harvest to the ground through three months of summer, and the hogs gathered them up and converted them into pork worth $12 an acre, without any effort on the part of the owner. The mulberry area in the United States is probably close to a million square miles. Over most of the region south of Mason and Dixon's Line the persimmon is a hated tree weed; yet it stands by the millions in fields and fence rows, fairly bending down with a full crop of fruit every other year, which is much sought after by the opossum and other wild animals, and eaten when possible by the American porker from September, the end of the mulberry season, until March, for the persimmon has a habit of dropping its fruit through the long winter period. The oak whose acorns probably made the pig what he is, is almost neglected in America; yet for ages the Indians of the Pacific coast have made their bread from acorns of two species of oak, one of which is now gathered by the farmers of California, put into their barns and bought and sold as stock food. The beechnut and the hickory nut are rich and much prized swine food.
Legumes, of which there are many species, can be grown between nut-yielding trees to maintain the fertility of the soil through the nitrogen gathering nodules upon their roots.
As it often seems desirable to cultivate trees of this character where possible, the tree crops agriculturist is above all others able to adjust his crop and the one device that permits the tillage of hilly land—terracing. Terraces interfere with machinery which is so increasingly essential in the cultivation and harvesting of the present crops. But terracing interferes least of all with the tree crop agriculture, because the trees can stand in the terrace rows and make a fortunate combination of the heavy yielding tree crops and the soil preservation through terracing.