1919] 



Pendleton: A Study of Soil Types 



:<«.'.-, 



1.7% to 3.5%, with the average of 2.66 ( /r , while the Hanford fine 

 sandy loam varies from 1.3% to 5', . with the average of 2.68%. 

 There is no question that here the range of values within every type 

 is greater than that from type to type. Even excluding those sam- 

 ples shown by the mechanical analysis to be not true to name there 

 is a wide range within each type — a range too wide to allow one 

 to answer the question of this paper in the affirmative. 



% 



0.3 



0.2 



0.1 



0.0 



P 2 5 

 N 



6 Soils 



Fig. 11. Graph showing the percentages of nitrogen and of phosphorus in 

 the four samples of Diablo clay adobe. 



The Chemical Data 



Total Nitrogen 



Diablo clay adobe. — There is more variation in nitrogen content 

 between the different representatives of the type than one would 

 expect from a visual examination of the soils (table 12 and fig. 11). 

 No. 2 would be expected to contain less nitrogen than no. 5 because of 

 the lighter color, but such is not the case. In the A horizon, no. 5 

 shows the lowest notal nitrogen content with 0.084%, no. 2 is higher 

 with 0.092%, no. 1 with 0.104%, and no. 6 is the highest with 0.117%. 

 The decrease in the nitrogen content with the increase in depth is 

 normal. In the C horizon, no. 1 has the lowest total nitrogen content 

 with 0.0577c, and no. 6 the highest, with 0.078%. 



Altamont clay loam. — The agreement between the A samples is 

 fairly close (table 13, and fig. 12). No. 4 has 0.103%,, no. 7, 0.104' , . 

 and no. 3 has 0.123%. This gives an average for the surface soil of 

 0.110%, as compared with 0.099% in the Diablo clay adobe. It is to 

 be noted that the nitrogen content of the subsoil is relatively less 

 than that in the Diablo subsoils, 0.071% and 0.056% in the Altamont 

 B and C horizons, respectively, as against 0.076% and 0.065% in the 



