78 BOOKS AND CURRENT LITERATURE 



Water requirement of Amaranthus graecizans 



Amaranthus graecizans 1.0 



Sorghum, blackheaded kaffir 1 .01 



Sorghum, dwarf milo 1 .21 



Corn 1 .34 



Wheat 1 .84 



Barley 1 .96 



Oats ; 2.23 



Alfalfa 3 .88 



It is of interest to observe that the water requirement of the annual 

 Amaranthns, which is a highly successful weed, is less than that of any 

 cultivated form growing under the same conditions. The water re- 

 quirement of Artemesia, the native peremiial, on the other hand, is 

 greater than sa\y used in the experiments excepting only the peas and 

 alfalfa. Thus we have the novel conclusion that the most perfectly 

 drought resistant species, of those experimented with, requires more 

 water to produce a given amount of dry matter than the ephemeral 

 species which are but slightly drought resistant! This is explained by 

 the authors as a result of the slow growth of this species. — ^W. A. C. 



Nitrate Determination. — The problems, purel}- scientific and ap- 

 plied, relating to nitrification in soils have been subjected to some careful 

 researches. Since their solution is of such vital importance the writers 

 of the present paper^ call attention to certain inaccuracies which arise 

 out of the employment of the colorimetric method for determining ni- 

 trates. They find that the alkali salts which occur frequently in arable 

 soils in California interfere with the phenoldisulphonic acid method 

 of nitrate determination. Sodium chloride, because of its chlorine, in- 

 duces much greater losses than sodium sulphate while sodium carbon- 

 ate has no effect. Explanation of this lies in the fact that sodium sul- 

 phate induces the loss of nitric acid from the solution, while the latter 

 is being evaporated, and that sodium carbonate, containing only a 

 weak acid radicle, possesses no such power. Lime is more reliable in 

 coagulating clay and organic matter from solutions in which nitrates 

 are to be determined, as it induces smaller losses of nitrates, than bone 

 black, which is most commonly employed, or potash alum and alumin- 

 ium cream. — Frederick A. Wolf. 



^ Lipman, C. B. and Sharp, L. T. Studies on the phenoldisulphonic acid 

 method, for determining nitrates in soils. Univ. of Calif. Publ. in Agr. Sci. 1: 

 No. 2, 21-37. 1912. 



