With the idea of getting practical results sooner, since nut trees
mature slowly, I interplanted my nut trees with varieties of apple, plum
and cherry. Doing so also served to economize on ground, since
ultimately nut trees require a great deal of space for best growth.
Walnut trees, for example, should be set 40 to 60 feet apart in each
direction.

[Illustration: _Pinus Flexilus nut seeds, Natural Size_]

I learned a variety of facts during these first years of trial and
error. I discovered, for instance, that iron fence posts rust away in an
acid soil; that one must use cedar or oak. Conversely, in alkaline soil,
iron will last indefinitely, but that the nitrogenous bacteria will
quickly rot wooden posts. I found that the secret of growing hickories
successfully lies in giving them plenty of room, with no forest trees
around to cut off their supply of sunlight and air. I learned that it is
impractical to graft a large forest tree of butternut or hickory.
Incidental to that, I learned that a branch of a butternut tree which
looks large enough to support a man's weight near the trunk, will not do
so when the branch is green and alive, but that a dead branch of similar
size will. Contrariwise, even a small green limb of a bitternut-hickory
will bear my weight, but an old limb, though several inches thick,
becomes so brittle after it is dead for several years that it will break
under slight pressure. Fortunately, falls from trees do not usually
result in serious injuries but I did acquire quite a few bruises
learning these distinctions.

There is always a natural mortality in planting trees, but in those
first years, lacking badly-needed experience, I lost more than 75%.