BOOKS AND CURRENT LITERATURE 



Methods in Nutrition Experiments. — A comprehensive but con- 

 cise paper by Schreiner and Skinner 1 emphasizes the great value of the 

 triangular diagram (showing the relative proportions of three constit- 

 uents when the sum of all three remains the same in all cases) in ferti- 

 lizer studies. A number of studies on solution cultures and sand cul- 

 tures as well as on field tests, in which this system was employed, are 

 mentioned and cited. Moreover, this paper is full of pictures and 

 diagrams showing the authors' own devices as well as those of other 

 writers, and these serve to illustrate the simplicity of planning nutrition 

 experiments and presenting or interpreting the results obtained there- 

 from, when the triangular diagram is employed. Methods for laying 

 out plats for fertilizer study in the field and for making fertilizer mix- 

 tures differing in salt proportions, by equal stages or increments (these 

 being indicated by stating the fractional part — per cent — represented 

 by each salt in the mixture), are likewise described. 



In the preparation of fertilizer mixtures the authors make their 

 calculations on the basis of equivalents of P 2 E , NH 3 , and K 2 0. While 

 there seems to be no plausible reason for adhering to this old-fashioned 

 method — which easily leads to erroneous conceptions — } r et the authors 

 calculated their essential elements in this way so as to be "in con- 

 formity with fertilizer practice, even when the nitrogen, for instance, is 

 in the nitrate form." There are histoirc reasons for the prevalence of 

 these curious bases for calculation in fertilizer practice, but it seems 

 desirable that the acknowledged leaders in this sort of work might soon 

 begin to improve fertilizer practice by introducing a more logical method 

 of calculation and comparison. It is not easy to fix upon any atomic 

 group that will surely represent the relative nutritional value of each 

 of the three elements, potassium, phosphorus, and nitrogen, but it is 

 safe to say that the nutritional values of any three substances supply- 

 ing these elements are surely not in proportion to the K, P, and N 

 •contents of these substances when these contents are calculated as 

 K 2 0, P 2 5 and NH 3 , respectively. It seems desirable to let the K, P, 



1 Schreiner, Oswald, and J. J. Skinner. The triangle system for fertilizer 

 experiments. Amer. Soc. Agron. 10: 225-246. 191S. 



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