acre per year were added to this thirty-two million acres—a rather large result to follow from an endowment of one or two millions.
The variation of plants of the same species has received frequent mention. One more point needs to be presented in connection with the idea of breeding desert trees. They sometimes vary fifty per cent, or more in the amount of water required to produce a given result. This variation within the species suggests an interesting line of experimentation with different species and strains,[1] to find the most efficient for particular places.
XIV. TWO-STORY AGRICULTURE FOR LEVEL LAND
Lastly I wish to submit the thesis that the trees now unused or little used as crop mediums may be the best kind of crop for some of our levelest and most arable lands. I have in mind a two-story agriculture with tree crops above and tilled crops beneath. By analogy I would recall the French practice (page 166) of scattering walnut trees all over the farm while going on with the farming. This does not sound alluring to the machine-using American, but let us consider it. Suppose you had a farm on the sandy plain somewhere between New York and Galveston. You are growing hogs and letting them
- ↑ See "Water Requirements of Plants as Influenced by Environment," L. J. Briggs, and H. L. Shantz, Proceedings, Second Pan-American Scientific Congress, Washington, 1915.
The variety of wheat having highest water requirement was eighteen per cent, above the lowest, corn thirty-one per cent., vetch thirty-five per cent., alfalfa forty-eight per cent., sorghum sixty per cent., and millet seventy per cent. I regret that Messrs. Briggs and Shantz did not test trees. I should expect similar results among them.
miles combine with the adjacent range land to support animals and the family in a way that could not result if all the irrigated land were in one block.
Similarly millions of scattered fruit, nut, and bean trees in the ranch country would meet their greatest need in helping to feed both the family and the flocks, with occasional small surpluses or specialties for export. The chief cash value would reach the world market in form of meat and wool and hides in exchange for an infinitude of manufacturers.
