236 BuLivETiN 89 



For the investigation which forms the basis of this report 

 two series of samples were taken : one set of ten for chemical 

 analysis and another of eight large samples for pot cultures and 

 physical tests. A few other samples for special determinations 

 were also taken. The chemical analysis was restricted to thr: 

 determination of acid insoluble material, of total potassium and 

 phosphorus, and 1.115 sp. gr. hydrochloric acid and 2 percent 

 citric acid soluble potassium and phosphorus. The results are re- 

 ported in Table IV. 

 6915. Small area of shale-like clay soil adjoining Hill's nursery; 



possibly the same as the clay strata seen on the edge of the 



mesa. 



6917. Surface foot of sandy soil from center of Sec. 9; this layer 

 did not show lime concretions. 



6917a. Second foot in same hole containing abundant lime concre- 

 tions. 



6918. Average of first three feet avoiding surface six inches of 

 wind blown sand ; soil homogeneous to bottom of hole ; south 

 side of N. W. corner of Sec. 15 near the edge of a pot hole; 

 Project A. 



6919. Tarnished sand from south of center of east of S. W. ^ of 

 Sec. 4 at depth of three feet. Surface was calcareous cemented 

 sand ; typical of the tarnished sands that make up the greater 

 part of the Mesa soil. 



6920. Surface cemented sand from same hole as 6919. Fifty feet 

 away this same cemented sand occurred at depth of two feet ; 

 sometimes spoken of as hardpan, but disintegrates immed- 

 iately when moistened. 



6922. First foot from a little N. W. of the S. E. corner of the 

 proposed experiment station tract. A small amount of lime 

 was seen near bottom of the hole at about three feet depth. 



6923. Third foot from south of middle of Sec. 7, Project B. The 

 sand at this depth appeared slightly less tarnished than the 

 first foot, which was the typical tarnished sand of the Mesa. 



6924. Second foot from same hole, containing some lime concre- 

 tions. 



6925. First foot same hole ; typical of a large tract wdiich shows 

 less variation than the north end of the Mesa in Project A. 

 The material represented in 6915 is not important, since it was 



niiled at dv near the surface in very small areas. It is a highly 

 calcareous alkaline clay which accounts for the low content of 

 msoluble matter. It is probably the most abundantly supplied 

 with mineral plant food of any soil on the Mesa, and when sufficient 

 water is available can be leached free from injurious amounts ot 

 alkali. It is omitted in averaging the composition of the Mesa 

 soils. 



