I do not know how far the mulch-fertilizer method can go, but I am sure it may go much farther than most professional horticulturists will admit. I find that the pecan tree starts off nicely under the mulch fertilizer conditions of the apple. The walnut tree has certainly done it for ages with less aid, and I believe it is up to us to find methods of handling land and trees and moisture which will enable us to avoid the danger, costs, and difficulties of plowing rough land and still get good trees. For example, the absence of cultivation does not necessarily imply the absence of fertilizer. The way a few black walnut trees in my apple orchard have snapped their buds and grown in response to the nitrate of soda that has been put upon the apple trees beside has been little short of astounding. The way a poor little starveling persimmon wakes up when the same treatment comes along, is equally interesting. I cannot speak definitely yet about the influence of fertilizer on the Persian walnut or the pecan.
In connection with the fertilization matter, it is well known that a crop of clover or other legumes is very important as a part of the rotation of crops in plow agriculture. Similarly I expect great value can be obtained in our pastured and fertilized nut orchards if we so treat the soil with lime, phosphorous, and whatever else is needed, to give a good mat of white clover and other legumes which are undoubtedly a good nitrogen supply for trees whose roots interlace with theirs.
Similarly I see great possibilities in the interplanting of some leguminous crop tree such as the honey locust or the Kentucky coffee bean in our nut orchards. It is true neither of these trees has yet been selected and developed to the crop point, but they are much more promising than Sargent says the wild Persian walnut was at its beginning. It is an established fact that a non-leguminous plant can take nourishment from the nitrate-bearing nodules on the roots of adjacent living legumes, to say nothing of its well-known ability to feed upon the nitrate collections of legumes that have lived in past seasons within reach of its roots. Thus the interplanting of a legume and a nut tree seems to promise a continuous supply of the all-important nitrates for the nut tree.