302 



Journal of Agricultural Research 



Vol. XIX, No. 7 



determinations uniformly distributed over a plot on a field at the San 

 Antonio Experimental Farm of the Office of Western Irrigation Agriculture. 



Hastings (6) has given a condensed account of the soil conditions of 

 the San Antonio region. A map of the experimental farm by Hastings 

 (7, p. 2) shows the location of field C3 in which this plot of borings was 

 located* and gives meteorological conditions prevaihng in 191 5, the 

 year in which the borings were made. 



Mr. C. S. Scofield kindly informs me that field C3 had been uniformly 

 treated for some time previously and was in apparently uniform con- 

 dition. It is nearly level but with a gradual slope to the south and east. 



The soil has the superficial appearance of uniformity, but we know from experience 

 that the subsoil, which is usually characterized by a high lim^ content, is in some 



Fig. 10. — Diagram showing location of sample areas examined for soil moisture in a field at the San 

 Antonio Experimental Farm. 



places much closer to the surface than in others. However, from a general agronomic 

 standpoint, this field would be regarded as extremely imiform, and observation of it 

 diuing the growing season would tend to confirm this view. 



Borings were made 6 feet in depth and were sampled at every foot.^ 

 Figure 10 shows the form of this field. 



In order to reduce the 100 sample areas to 2 by 2 fold combinations we 

 have discarded the right file and a portion of one rank, retaining only 

 those which can be grouped into fours as indicated by the cross lines. 

 The percentages of moisture content of these 100 sample areas appear 

 in Table III.=* 



' The northern border of the sampled area is a line 60 feet south of the north line of the field and parallel 

 to it. 



2 The samples were all taken between March 31 and April 9. During this period there was no rain. 

 Between March 15 and April 10 there were only two rains, one on March 17 of 0.2 inch, the other on March 29 

 of o.oi inch. Neither of these was sufficient to affect the soil moisture conditions, since in this region a 

 precipitation of less than 0.25 inch scarcely penetrates the surface-soil mulch. Thus moisture changes 

 during the course of the work can hardly influence the results. 



2 The 1 2 sample areas which were omitted because of impossibility of combining by fours are starred (*). 



