1916] SOILS FERTILIZERS. 217 



" Increases in ammonification due to the applications of humus-forming 

 materials were independent of the nitrogen-carbon ratio of the materials 

 added. . . . The dried-blood-fresh-soil method gave better results for am- 

 monification than the casein-fresh-soil method. The latter gave better dupli- 

 cate results, but the differences between different soils were not nearly so 

 pronounced. . . . 



" Nitrification was increased in much the same way as ammonification by 

 the various organic materials. The leguminous green manures exerted, how- 

 ever, somewhat greater effects than the manures, and also more influence 

 than the nonlegumes. These results were the opposite of those secured with 

 ammonification, but the differences were not great enough to permit of definite 

 conclusions. Increases in nitrification brought about by the various materials 

 were apparently independent of the nitrogen-carbon ratio in the substances. 

 Indications of a greater effect of materials of a narrower ratio over those of 

 a wide ratio can not be considered conclusive. 



"Azofication or nonsymbiotic nitrogen fixation was favored by manure to a 

 large extent. Straw, stover, and nonleguminous hays had almost as great an 

 effect as to the manures, and the leguminous hays had the least effect of any 

 of the materials used. The nitrogen-carbon ratios of the materials employed 

 were of little or no significance in indicating their effects on azofication. There 

 were indications, however, that nonlegumes and straws might increase azofica- 

 tion in soils to a large enough extent to make their use more profitable than 

 that of legumes. . . . Dextrose gave better results in the azofication experi- 

 ments than mannite. . . . 



" There was little similarity between the effects of the different organic ma- 

 terials on the diiferent bacterial processes. . . . The manures and legumes in- 

 creased the first crop of oats, except in the case of the horse manure, which 

 apparently exerted an injurious effect on the crop in its early stages of 

 growth. . . . 



" The substances with wide nitrogen-carbon ratio decreased the crop yield, 

 while those of narrow ratios gave increases. The nitrogen factor was evi- 

 dently very important on this soil. The nitrogen-carbon ratio of the organic 

 materials seemed to be of importance in determining the influence on the 

 first crop of oats. If opportunity is to be given for nonlegumes to exert as 

 good an effect as legumes, by increasing azofication to a sufficient extent to 

 offset the nitrogen supplied by the legumes, the organic materials must be al- 

 lowed sufficient time for considerable decomposition to occur before a crop is 

 grown. . . . The influence of the various substances applied to the soils was 

 noted on a second crop of oats, but the relative effects were different. The 

 nonlegumes had as great an influence as the legumes. . . . The nitrogen-carbon 

 ratio of the materials applied to the soil did not seem to be of as much im- 

 portance in determining the effect on the second crop of oats as in the case 

 of the first crop." 



Pour references to literature bearing on the subject are cited. 



Contribution to the question of the action of stimulants on plant develop- 

 ment, B. ScHULZE (Landw. Vers. Stat., 87 (1915), No. 1, pp. 1-24, flff- 1; O'^s. in 

 Jour. Chem. Soc. [London], 108 {1915), No. 636, I, p. 926; Jour. Soc. Chem. 

 Indus., 34 (1915), No. 22, p. 1151; Chem. ZentU., 1915, II, No. 11, p. 622).— Pot 

 experiments on a clay soil mixed with compost to determine the stimulating 

 influence of the hydroxid, carbonate, nitrate, phosphate, and sulphate of man- 

 ganese and of aluminum sulphate, singly and in different combinations, on 

 the growth of sugar beets, when added in amounts equivalent to from 1.2 to 

 12.2 gm. of manganese per 20 kg. of soil, are reported. 



