676 ABSTRACTS 



Influence of Barnyard Manure and Water upon the Bacterial Activities 

 of the Soil. J. E. Greaves and E, G. Carter. J. Agr. Res., 1916, 

 6, 889-926. 



This is a report of a fairly extensive investigation of the bacterio- 

 logical effects of different quantities of manure and water added to 

 soil. Plate counts are made on Lipman's "synthetic agar." Determi- 

 nations of ammonifying and nitrifying powers of the soil are made by 

 the tumbler method, while nitrogen-fixing powers are determined by 

 adding the soil to Ashby's solution. Part of the work is done on 

 potted soil, part on field soil. The detailed results are too many to 

 give in a brief review; but in general the writers find a direct rela- 

 tionship between the bacterial count, the ammonifying powers, the 

 nitrifying powers, and the crop produced. As a rule all these factors 

 are increased with increasing amounts of manure, and with increasing 

 moisture content up to at least 20 per cent. — H. J. C. 



The Effect of Time and Depth of Cultivating a Wheat Seed Bed upon 

 Bacterial Activity in the Soil. P. L. Gainey. Soil Science, 1916, 

 2, 193-204. 



Call of Kansas presented a paper concerning the effects of different 

 methods of preparing a seedbed for wheat upon yield, soil moisture, 

 and nitrates. Gainey's article is concerned with the very marked ef- 

 fects of the various experimental methods of Call upon the accumu- 

 lation of nitrates. Gainey determined from his own experimental 

 evidence that the differences in nitrate content reported by Call can- 

 not be attributed to a difference in the bacterial content. Some 

 non-biological condition existing in certain plots under field conditions 

 prevents the normal activity of the bacterial flora. Among the factors 

 controlling bacterial activity, the available moisture probably plays a 

 paramount role. — Z. N. 



Azotohacter in Hawaiian Soils. P. S. Burgess. Soil Science, 1916, 



2, 183-192. 



Thirty soils from different localities on the four large islands of the 

 Hawaiian group were examined as to their azotobacter content, and 

 their abilities to fix nitrogen in mannit solutions. Only five of the 

 soils failed to show azotobacter growth in solutions. Four different 

 forms of azotobacter were isolated in pure cultures, described and their 

 abilities to fix nitrogen in solutions and in soils determined. A pos- 

 sible explanation of the introduction and distribution of azotobacter 

 in these isolated island soils is given. With the introduction of com- 

 mercial mixed and single element fertilizers, a fine soil is sometimes 

 used as a "filler." Azotobacter species may have been carried in the 

 latter, as it is never sterilized. The imported organic fertilizers, leg- 

 ume seeds, etc., may also have been carriers of this bacillus. — Z. N. 



