182 SOIL. 



cient 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. 



Lcachy Substrata. \Yhile we may thus overcome the dis- 

 advantages of a dense subsoil or hardpan, there is another diffi- 

 culty 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 tilled up. will be clearly outlined by the dying 

 crops, while outside of the old channels there may be no suffer- 

 ing. 



"Going-back " <>f OrcJianls. 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 sud- 

 denly languish, or turn yellow and die. as the demand of their 

 larger growth exceeds what moisture or plant-food the shal- 

 low soil and subsoil ean supply. Knormous losses have arisen 

 from this cause in many portions of the arid region, but more 

 especially in California, owing to the implicit confidence re- 

 posed even by old settlers, and still more by neu comers, 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 format ions. All such 

 disappointments could have been avoided by an intelligent ob- 

 servation of the substrata, either by probing or digging. Im- 

 portant as is such preliminary examination in the region of 

 summer rains, it is a vitally needful precaution in the arid 



