554 APPENDIX A. 



this will usually happen at from six to nine inches from the surface, 

 and a sample taken to that depth will constitute the "soil." 



In California and the arid region generally, very commonly no change 

 of tint occurs within the first foot, sometimes not for several feet ; 

 hence, especially in sandy lands, the " soil " sample will usually be taken 

 to that depth, so as to represent the average of the first foot from the 

 surface down. 



Samples taken merely from the surface, or from the bottom of a hole, 

 have no definite meaning, and will not be examined or reported upon. 



Place the " soil " sample upon a cloth (jute bagging should not be 

 used for the purpose, as its fibres, dust, etc., become intermixed with 

 the soil) or paper, break it up, mix thoroughly, and put at least a quart 

 of it in a sack or package properly labeled, for examination. 



This specimen will, ordinarily, constitute the " soil." Should the 

 change of color occur at a less depth than six inches, the fact should be 

 noted, but the specimen taken to that depth nevertheless, since it is 

 the least to which rational culture can be supposed to reach. 



In the same way take a sample of each foot separately to a depth 

 of at least three feet ; preferably four or five, especially in the case of 

 alkali soils, or suspected hardpan. 



Sixth. Whatever lies beneath the line of change, or below the min- 

 imum depth of six inches, will constitute the " subsoil." But should 

 the change of color occur at a greater depth than twelve inches, the 

 " soil " specimen should nevertheless be taken to the depth of twelve 

 inches only, which is the limit of ordinary tillage ; then another speci- 

 men from that depth down to the line of change, and then the " sub- 

 soil " specimens beneath that line. 



The depth down to which the last should be taken will depend on 

 circumstances. It is always necessary to know what constitutes the 

 foundation of a soil, down to the depth of three feet at least, since the 

 question of drainage, resistance to drought, root-penetration, etc., will 

 depend essentially upon the nature of the substratum. In the arid 

 region, where roots frequently penetrate to depths of ten or twelve feet 

 or even more, it is frequently necessary to at least probe the land to 

 that depth or deeper. The specimens should be taken in other respects 

 precisely like that of the surface soil, each to represent the average of 

 not more than twelve inches Those of the materials lying below the 

 third foot from the surface may sometimes be taken at some ditch or 

 other easily accessible point, and if possible should not be broken up 

 like the other specimens. 



