SOILS FERTILIZERS. 721 



pp. S69-3S5). — This is a detailed account of investigations vvbicli liave already 

 been noted from a briefer paper (E. S. R., 26, p. 816). 



Relations of the plant to the nutritive elements of the soil: The law of 

 minimum and the law of physiological ratios, P. Maz6 {Compt, Rend. Acad. 

 Sci. [Paris], 15-'t (1012). Xo. 25. pp. 1111-1111, fig. 1; abs. in Rev. G6n. Agron., 

 n. ser., 7 {1912), Xo. 8, pp. 292-293; Jour. Hoc. Chem. Indus., 31 (1912), No. U, 

 p. 695). — The author's experiments with maize and Aspergillus nigcr, usiug 

 various kinds, amounts, and relative proportions of mineral substances In the 

 culture solutions, led to the conclusion that the law of minimum, particularly 

 as defined by Mitscherlich (E. S. R., 25, p. 825) is a purely speculative concep- 

 tion. The relation of the plant to its nutritive substratum is determined by 

 complex conditions controlled by a law which is designated the law of physio- 

 logical ratios, that i.s, the growth of the plant is determined not solely by 

 the nutritive constituent present in minimum amount but by the concentration 

 and relative proportions of the constituents in the nutritive medium. 



The law of minimum, E. A. Mitsciieklicu, T. Pfeiffer, and O. Fbohlicu 

 (Landw. Vers. Stat, 77 (1912), No. 5-6, pp. 413-.'t39, figs. 4).— This is a series 

 of three controversial articles on this subject. See above. 



Experiments on ammonia and nitrate formation in soils, J. G. Lipman, 

 P. E. Brown, and I. L. Owen (Xeiv Jersey Htas. Rpt. 1910, pp. 8.9-/2.'/).— In 

 continuation of previous investigations (E. S. R.. 25, p. 423) experiments were 

 made to test further the accuracy of the method used and " to accumulate data 

 on the decomposition of protein compounds in the soil." The experiments here 

 reported dealt with the effect of mechanical comi>osition of the soil, moisture 

 conditions, lime, and various physical and chemical factors on the formation of 

 ammonia in soils. The results obtained in a series of experiments uniformly 

 indicatetl a high degree of accuracy for the method. 



Varying the proportion of sand in the soil had little effect on the formation 

 of ammonia from dried blood, but affected to a marked degree ammonia accumu- 

 lation, the latter declining as the proportion of sand increased. In pot experi- 

 ments it was found that addition of sand to soil increased the availability of 

 nit4'ogen as measured by the nitrogen content of the crop. 



" The influence of the increasing amounts of moisture in the soil is apparent, 

 on the one hand, in the increasing yields of dry matter and, on the other, in the 

 decreasing proportion of nitrogen in the latter. The average yield of dry 

 matter gradually rose from 13 gm. to 20.75 gm., but when the proportion of 

 water in the soil mixtui'e was increased from 13 to 15 per cent the yield of dry 

 matter was somewhat decreased. The proportion of nitrogen in the dry matter 

 was highest when the soil mixture contained only 5 per cent of moisture. It 

 was least when the soil mixture contained 15 per cent of moisture. Similarly, 

 the yields of total nitrogen Increased from 266.86 to 292.47 mg. when the 

 moisture content in the soil rose from 7 to 9 per cent. Further additions of 

 moisture were followed by corresponding increases, the maximum yield being 

 attained in the soil mixtures containing 13 per cent of water. After that there 

 was a small reduction in the yield of nitrogen." 



" The decomposition of organic matter in the soil was favored or retarded by 

 additions of magnesian and nonmagnesian lime according to the character of 

 the organic matter." In experiments with a commercial carbonate of lime 

 containing 2 per cent of boron the latter proved injurious to higher plants and 

 to decay bacteria in the soil. 



Wide variations were found in the ammonia formation in soils from different 

 sources. 



The addition of monocalcic and dicalcic phosphates to soil greatly increased 

 ammonia formation. Tricalcic phosphate was without effect. " It seems, there- 



