316 EXPERIMENT STATION RECORD. [Vol. 41 



SOILS— FERTILIZERS. 



Are soils mapped under a g'iven type name by the Bureau of Soils method 

 closely similar to one another? R. L. Pendleton {Univ. Cal. Puhs. Agr. Sci., 3 

 (1919), Xo. 12, pp. 369-P8, pis. 32, figs. 57).— This study conducted at the Uni- 

 versity of California is an attempt to see whether certain soil types, mapped as 

 the same from different areas of California and judged to be the same by tlie 

 criteria used by the Bureau of Soils of the U. S. Department of Agriculture, 

 are the same or similar when examineil from the laboratory standpoint. Twenty- 

 four presumably typical samples of four soil types from widely distributed 

 localities in the State were submitted to physical, chemical, and bacteriological 

 analyses and to pot culture tests to determine their ability to produce different 

 crops. 



With reference to physical relations between the soils, it was found that the 

 mechanical analysis by the Hilgard elutriator showed that the soils of a given 

 type were in some cases quite divergent from each other in their content of 

 certain of the sizes of particles. The mechanical analysis by the Bureau of 

 Soils method showed that 6 of the 24 soils were not true to their type names, 

 and that of those soils within the type there was considerable variation. The 

 moisture equivalents for the several types showed distinct enough values to 

 substantiate the field separation. The hygi'oscopic coetticients varied widely 

 within each type, and the types were not shown to be distinctly different by this 

 criterion. 



With reference to chemical relations it was found that the total nitrogen 

 averages varied markedly from type to type, with the Altamont clay loam con- 

 taining three times that in the San Joaquin sandy loam. The average humus 

 content of the San Joaquin samples was about half that of the other types. The 

 variations in humus content between the types were small, considering the 

 diverse nature of the types and the large range in the amount of humus within 

 the type. The loss on ignition showed considerable variation within the type 

 and no significant distinction between the four types. The average total calcium 

 content of the types was distinct, though the wide range within each type 

 minimized the significance of the variation in the averages. With regard to 

 magnesium, the types were neither distinct nor were the soils within the type 

 closely similar. The average phosphorus content of the types was distinct, 

 though the ranges within the sevei'al types frequently overlapped. The total 

 potassium results did not show the types to be distinct nor the soils within a 

 type closely similar. 



With reference to bacteriological relations, it was found that the ammonify- 

 ing power showed rather larger variations from type to type than between the 

 samples of a type. The nitrogen fixation data did not show characteristic dif- 

 ferences for the several types. 



" Regarding nitrification as a whole there may be a greater divergence be- 

 tween the samples of a type than between types. The relative nitrification of 

 the soil's own nitrogen varies with the type, as does the relative nitrification 

 of the several nitrogenous materials added." 



Pot cultures in the greenhouse showed that " different representatives of a 

 given type are not the same in their ability to produce crops. The arrange- 

 ment of the samples of a given type according to their fertility may or may not 

 vary with the special crops used as the indicators. The types are distinct with 

 respect to their fertility, considering their average production. Therefore it is 

 concluded that with regard to the 24 soils of four types examined, all soils 

 mapped under a given name by the Bureau of Soils method may or may not 

 be closely similar, depending upon the criteria used. Tlie greater number of 



