many inches.[1] Under these distressing conditions the yield diminishes until finally the place goes back to pasture. The amount of this loss in one or two decades will astonish one who looks up the facts.
Using the Leguminous Tree as Source of Nitrogen
I am sure that many of these pastures would have their productivity as pastures increased if they could be thinly covered with a planting of some leguminous tree whose roots would gather nitrogen from the air and leave it in the earth where the grass roots could share it. I cannot prove that statement statistically, but on the other hand I believe that it is also true that there are no experiment stations in the United States that have data to disprove it or to prove it. Such data would be very valuable and reasonably easy to secure.
My opinion is derived from observing that good grass grows under locust (robinia) and honey locust trees in pastures, sometimes in places where nearby lands are desolately bare. I have seen conspicuous examples of this on some of the shale hills of Bedford County, Pennsylvania. Certainly my opinion is backed up by an editorial in the Breeder's Gazette (1926).
I believe the owners of such pastures in natural blue grass country would get more grass if their fields had compact clumps of about twenty-five yellow locust trees set one hun-
- ↑ See the very illuminating and discouraging article in American Forests, June, 1927, in which Mr. Hugh Hammond Bennett, United States Bureau of Soils, states, "On the watershed of the Potomac River the writer recently checked the amount of soil wastage over some of the mountainous country from whence comes the water supply of the national capital. It was found even on the smoother plateaus that from five to eight inches of top-soil had been removed from most of the cleared land. This condition obtained in many places where crops had been grown only fifteen or twenty years, and the exposed subsoil of clay and rock was so infertile that powerty grass was the principal plant seen in many pastures and abandoned fields. Remaining patches of original forest with their undisturbed virgin soil served as an index to what has happened."
