_Shattering of Dense Substrata by Dynamite._—The permanent loosening of dense substrata is best accomplished by moderate charges (½ to ¾ pounds) of “No. 2” dynamite at a sufficient depth (3 to 5 feet). The shattering effect of the explosive will be sensible to the depth of eight feet or more, and will fissure the clay or hardpan to a corresponding extent sidewise. If properly proportioned the charge will hardly disturb the surface; but if this be desired, from 1½ to 2½ pounds of black powder placed above the dynamite will throw out sufficient earth to plant the tree without farther digging. Where labor is high-priced this proves the cheapest as well as the best way to prepare such ground for tree planting; and it has often been found that in the course of time, the loosening begun by the powder has extended through the mass of the land so as to permit the roots to utilize it fully, and even to permit, in after years, of the planting of field crops where formerly they would not succeed. _Leachy Substrata._—While we may thus overcome the disadvantages of a dense subsoil or hardpan, there is another difficulty not uncommonly met with in alluvial lands, which cannot be so readily remedied. It is the occurrence, at from two to six feet depth, of coarse sand or gravel, through which capillary moisture will not ascend, but through which irrigation water will waste rapidly, leaving the overlying soil dry. Then unless very frequent irrigation can be given, the crop will suffer from drought, unless indeed the gravel itself is filled with bottom water upon which the root-ends can draw. This case is a common one in the larger valleys of the arid region, and in time of unusual drought the sloughs originally existing, but since filled up, will be clearly outlined by the dying crops, while outside of the old channels there may be no suffering. _“Going-back” of Orchards._ On such land as this, and on such as has a shallow soil underlaid by an impervious subsoil, trees will often grow finely for three to five years; then suddenly languish, or turn yellow and die, as the demand of their larger growth exceeds what moisture or plant-food the shallow soil and subsoil can supply. Enormous losses have arisen from this cause in many portions of the arid region, but more especially in California, owing to the implicit confidence reposed even by old settlers, and still more by newcomers, in the excellence of the lands, as illustrated by farms perhaps a short distance away, but differently situated with respect to the country drainage and the geological formations. All such disappointments could have been avoided by an intelligent observation of the substrata, either by probing or digging. Important as is such preliminary examination in the region of summer rains, it is a _vitally_ needful precaution in the arid region, where the margin between adequate and inadequate depth of soil and moisture-supply is much smaller.