Tap Root of a Two-year-old Black Walnut showing how the root grows down to permanent water level, thus insuring full crops regardless of weather conditions
Cut of tap root of a 2-year-old American Black which grew in the lower red hill land of Yamhill County. There is but one lateral root near the surface and this was probably caused by the tap root striking harder soil on its way down to permanent moisture level.
This tap root is 3 feet long and nearly 6 inches in circumference. It is one of the best object lessons to be had in walnut culture in Oregon.
Though the Willamette Valley has practically four rainless months of sunshine, irrigation is unnecessary. There is no other country comparable to it. Its cool and dewy summer nights, together with its great subterranean reservoir supplied by the winter rains, are the reasons why its crops never fail and why its fruits fill "red, round and luscious," and why the walnut has so persistently shown its preference for this favored region.
WALNUT CULTIVATION
While the walnut is the hardiest of trees and in many cases has borne heavily in Oregon without cultivation, experience has proved that, like fruit trees, cultivation up to the tenth or twelfth years increases the growth, the yield and the quality of the product. After full maturity no further cultivation is necessary, the tree taking care of itself with the independence of any forest tree.
With a young grove it is best to plow between the rows after the rains cease in the spring, and then stir the ground occasionally all through the summer with the harrow or disk; this holds the moisture. When some trees seem backward a trench should be dug some two feet or so away, and a couple of feet deep, filled with fertilizer and closed over. This will encourage hardier and more rapid growth. Lime can also be used with good effect, it being customary in England to haul wagon loads to the walnut lands. Continually hoeing and digging constitute the best treatment, as one tree on the Prince place, a Mayette, has proved. It was given daily cultivation, by way of experiment, and more than doubled the size and yield of other trees of the same age not so treated.