By far the best growth for most kinds of nut trees, as well as the best production of nuts, is to be found where trees are planted in deep loam. Next come the trees in clay loam; then come trees in sandy loam and in clay over sand or gravel. Numerous complaints of poor growth come from members who have trees set in a soil which is shallow over rock or hard-pan. Some of the hazels and butternuts are reported as able, for a time at least, to establish themselves in such soils, but their fight for survival seems precarious and is apparently short-lived. Black walnuts, particularly, require deep, rich soils into which their long taproots can easily penetrate. This is one of the few nut tree facts so definitely established that there can no longer be any doubt about it. The reports show that the planting of black walnuts in any but good deep soil should be discouraged. It leads only to disappointment and often to loss of interest.
A somewhat sandy soil, particularly if loamy, seems adapted to the planting of chestnuts and to such trees as do well on ground that will successfully grow peach trees. If such soil is found upon a hillside or hill top, so much the better. All such soils, of course, require more attention to fertility maintenance, for they leach out more quickly than soils with more of a clay constituent.
Do any of the nut tree species prefer an acid to an alkaline soil? This is a question our questionnaire does not answer. Thirty correspondents say their trees are set in a lime soil, fourteen in an alkaline soil (which may or may not, in the commonly accepted usage of that term, have lime as a source of alkalinity). Sixty-one report an acid soil. Only eight of this group report the use of lime, two the use of bone meal, and one of wood ash as acid correctives. Unfortunately, we did not ask definitely about the reaction of trees to the use or non-use of lime. Puzzled by this comparative neglect of lime as a corrective on acid soils, we asked Mr. H. F. Stoke, of Roanoke, Va., a very accurate and acute observer, who had reported plantings in both kinds of soils, what his experience had been. Also we asked Miss Mildred Jones, whose experience with nut trees is second to none, the same question. Their replies follow:
Mr. Stoke says: "In response to your inquiry, 'What nut trees, if any, do best in acid soils?' I should reply that the chestnut leads the list, followed closely by the mockernut hickory.
"Throughout its native habitat the heaviest stands of the native chestnuts are to be found on acid soils over granitic and sandstone formations, rather than on limestone ridges. The best stands are on granite ridges, partly due, no doubt, to the poverty of sandstone soils.
"The mockernut hickory occurs about anywhere on the poor, acid, clay soils of the south, its vigor depending on fertility. Shagbark does not occur on the acid (granitic) Blue Ridge mountains, but is found on the limestone Alleghanies running parallel only a few miles away. I have never seen a shagbark hickory between Roanoke and the coast, more than 200 miles away, but it occurs freely to within two or three miles on the west. The difference is not in elevation or rainfall, but in the soil.
"On the other hand, black walnut occurs on both acid and limestone soils, but seems to prefer the latter. Part of its preference may be due to the generally greater fertility and better drainage to be found in limestone soil. Persian walnut, I believe, when on its own roots, is more or less allergic to acid soil. Wild hazels grow here on both limestone and granite soils.
"Frankly, I believe the matter of soil acidity, as such, is rather over-emphasized. There are other factors entering into the problem that are of as great or greater importance. I doubt if there was actually any really alkaline soil, in its native state, in the humid region lying east of the Mississippi River. In the glaciated region lying to the north, the soil seems to have been more nearly neutral (pH 7). Such was the case in Iowa and in Minnesota where I homesteaded many years ago.
"Throughout the south the soil averages much more acid, even much limestone soil being greatly benefitted by liming. North or south, soil acidity is greatly affected by drainage and by the resulting native vegetation.
"Peat or muck soils are notably acid; also they are notably deficient in potash. The addition of wood ashes greatly benefits such soils in two ways. On the other hand, the addition of wood ashes to a soil already alkaline might be harmful even though in need of potash.