SOILS FERTILIZERS. 721 



Soils high in orgauic matter tixed as umuh nitrogen iu the presence of arsenic 

 and in the absence of mannite as they did in the presence of mannite and absence 

 of arsenic. The stimuhition is greatest when the water-soluble arsenic content 

 of the soil is about 10 i)arts per million; this quantity exceeds that found in 

 most soils, so it is likely that arsenic will stimulate in place of retard bacterial 

 activities of .soil. 



" Only one type of Azotobacter was isolated which was stinmlated by arsenic. 

 and in this case the stimulation was due to the organism utilizing more econonu- 

 cally, in the presence of arsenic, its source of carbon than it did in the absence 

 of arsenic. Arsenic does not act as a source of energy to the organism. Part 

 of the stimulation noted in the soil with its mixed flora is probably due to the 

 arsenic inhibiting injurious si^ecies. A quantity of arsenic which acts as a 

 stimulant to bacteria when jilaced in soil may become very toxic when tested 

 by the Keiny solution method." 



Bacteriolog'ical effects of green manures, C. F. Briscok and H. H. Haknicd 

 (Mi^si.ssiiJixi St(t. Bui. 168 {1915), pp. 20, figs. 7). — This bulletin gives a general 

 discussion of the relation of humus to soil bacteiua and reports a series of ex- 

 periments in stone jars which was designed primarily to test the effect of green 

 manures and stable manure on the rate of nitrification in soils. One series of 

 jars was arranged for the bacteriological tests and the other was cropped with 

 oats as a check on the bacteriological tests. 



The results iudicatetl a direct relation between the bacterial count and the 

 amount of organic matter added to the soil. There was a very unifoi'm agree- 

 ment between the bacteriological and the vegetative tests. It was found that a 

 light dressing of stable manure with green manure produced marked effects as 

 shown both by the crop tested and the bacterial count. The use of a bacterial 

 cultui'e with the green manure had as pronounced an effect as the addition of a 

 light dressing of stable manure, indicating that the benefit from the use of the 

 stable manure was due largely to the addition of the bacteria contained in the 

 manure. The addition of organic matter to the soil gave not only a larger 

 growth but a better quality of oats as shown by determinations of nitrogen in 

 the straw. 



The effect of appljring stable manure with green manures, O. Le)mmermann 

 and A. Einecke (Mitt. Dcut. Landw. Gesell., 29 (1914), No. 52, pp. 702-70.'f).— 

 Contrary to a generally accepted view the experiments with sugar beets reporte<l 

 in this article did not indicate that applying stable manure with green manures 

 (lupines and serradella) appreciably increases the effectiveness of the latter. 

 Plowing under the green manures in si)ri:ig gave better results than i)lowing 

 under about the end of October. Plowing under to a depth of 11 in. gave better 

 results than plowing under to a depth of S.7 in. Takiag the effect of nitrogen 

 in nitrate of soda as 100, that of the nitrogen of the green manures was 44 and 

 of stable manure 21. 



[Investigations on soils and fertilizers iu Hawaii], E. V. Wixcox and 

 W. P. Kelley (Haicaii Sta. Rpt. 191.',. pp. l.',-lil. 21. 22. 25-^).— Brief sum- 

 maries are given of the main results of investigations, including the effect of 

 heating on soils (E. S. R., 30. p. 419). fertilizing rice (E. S. R., 30, p. 420). the 

 nature of the nitrogenous compounds of soil (E. S. R.. 31, p. 11), effect of fer- 

 tilizers on the chemistry and physical i)ropertios of soils and on the fixation of 

 fertilizing constituents b.v soils, and ammonification and nitrification in soils (see 

 p. 710). 



It is statetl that " continued pot experiments with various forms of phosphate 

 have demonstrated anew that soluble phos|)hates do not leach through the soils, 

 but I'emnin permanently available for plant growth. It was also shown that 



