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