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.