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.

We have an interesting example of tree crop productivity in Hawaii, where the agaroba was introduced from Peru in the last century.  It has now spread until it covers considerable area with forests, and information from the Hawaiian Experiment Station is to the effect that it is now the mainstay of the dairy industry of the island.  The annual crop of four tons of big beans to the acre can be and is ground into a highly nutritious meal food selling at $25 a ton, an agriculture which, for ease of operation and richness of return, puts Illinois to shame, for, in addition to the $100 worth of animal food, there is a ton of wood per acre every year.

The tree crop agriculture seems to hold the possibility of letting the worst third of our soil (Class 1 as mentioned above) become as productive as the best land (Class 3), while (Class 2) the hill land can probably be doubled in productivity.  This is a goal well worthy of much endeavor on the part of the plant breeder.

Tree crops offer equal possibilities for the arid land.  The grains with their period of crisis are an uncertain dependence on land of such uncertain rainfall as exists in the United States west of the 100th meridian.  This is attested by the fact that some of this land has been settled three times and abandoned twice to the wreckage of hundreds of thousands of private fortunes.  Yet the tree with its far-reaching roots and ability to store energy can survive in much of this area where grains are so very uncertain.  The mesquite, yet a tree weed over much of this area, has one species which produces a nutritious seed that has been used for bread stuff by unknown generations of Indians.  The screw bean, a legume, with a nutritious seed, grows from El Paso to the Imperial Valley; while the broad leafed honey locust, with a seed closely akin to that of the carob, or St. John’s Bread, will also grow over wide areas in the arid southwest.  Five varieties of the small but productive wild almond have been found by a Government botanist growing upon the shores of Pyramid Lake; while Frank Myer, Plant Explorer of the Department, brings back from Turkestan accounts of wild almonds producing good fruit on mountain slopes with a rainfall of 8 inches a year.  These productive plants, several of them legumes, adjusted by nature to this region, with allied species in other continents, seem to hold before the plant breeder the possibilities of hundreds of thousands of square miles of Western orchard ranges of high productivity, rather than the present would-be grass-ranges of low and declining productivity.