down deep in the moist earth the kernel will not fill well and may perish entirely. For this reason no fibre of the tap root should be disturbed, but rather encouraged by a well auger hole, bored before the tree is planted, down to the reservoir of moisture that will not fail in the dryest season.
The moisture in a dry season as a rule is nearer the surface in the valley than in the hills and gives a better filled nut. In a wet season, when the ground everywhere is full of moisture, the hills may produce a more abundant crop than the valley, but in the run of years it will require more time to prove which is most valuable for walnut culture. Trees grow in either place, but he who cuts the tap root in any soil does so at the peril of his crop in dry seasons.
Of the taproot, Wm. M. Reece, of the firm of Epps, Reece & Tillmont, Eugene, Oregon, writes:
"The peculiar climatic conditions of the Willamette Valley, which at a certain season of the year becomes semi-arid, fully justifies the statement that trees not having a tap root are annually checked in their growth when irrigation is not used; while those that do have a tap root, as do walnuts, continue to grow and thrive even in the driest weather. The walnut should be planted, however, in soil having a subsoil free from any hard substance that will permit the tap root to grow downward into the strata of perpetual moisture.
"This has been most thoroughly demonstrated in our walnut orchard this, the driest year in the memory of old settlers in the Valley.
"When the growth of our apple, cherry and peach trees ceased because of the dry weather, our walnuts kept on growing as if supplied by continuous rains. It is true that liberal cultivation through the dry season will materially aid the growth of all kinds of trees not having a tap root and is indispensable to the growth of young walnut trees, trees that have not extended their tap root down to perpetual moisture.
"Walnut trees, in the opinion of the writer, cease growing upward when they cease growing downward; that is to say, when rock, shale or impenetrable hardpan stops the growth of the tap root, the tree has practically reached its height.
"Therefore, in planting a walnut grove, borings should be made to test the depth of the soil and character of the subsoil.
"Unquestionably the best variety for this climate is the Franquette and next the Mayette.