514 EXPERIMENT STATION RECORD. [Vol. 40 



was much more favorable. Eased largely on the results obtained during the 

 latter season the following conclusions have been reached: 



The number of bacteria increased rapidly during January in all soils, hoth 

 frozen and unfrozen, where raw material was available for bacterial decompo- 

 sition, this increase failing to materialize where raw material was absent. A 

 moderate increase in numbers amounting to from two to four times the original 

 number occurred in frozen soils during March. Severe frosts checked any 

 bacterial development in frozen soil. A high soil moisture content counter- 

 acted the frost action, while a low moisture content aided in the depression 

 of bacterial development. A sudden, severe frost killed mosl of the bacteria in 

 the exposed soil. A decrease in the numbers of bacteria was observed when 

 the soil thawed, while an increase in soil moisture was usually followed by an 

 increase in the number of bacteria. 



The work was continued along the same general lines during the winter of 

 1917-1* and observations made every two weeks of the bacterial contenl of the 

 different soils. Results confirming those noted above were obtained, a super- 

 ficial examination is said to Indicate that ammonification and denltrification are 



produced by extra-cellular and nitrification by intra cellular eiizyin action, 

 which is held to mean that the firsl mentioned processes could continue in 

 ffo/en soils even when further bacterial development was halted, while the 

 hit ter would be impossible. 



Champaign County soils, 0. G. HOPKXNS, .1. «:. Mi. -in:. E. Yv\ AXSTINK, and 

 F. W. GABRETT {Illinois st, i. Soil Rpt. /> {1918), pp. 61, pi*. 8, flfft. /•>). Cham- 

 paign County, situated in the easl central pari of the state, comprises an area 

 of 988 square miles. The topography of the region varies from Hat to slightly 

 rolling, while a few small areas occurring along the streams are to,, steep for 

 cultivation. The entire county was covered Br8l by the Illinois, then \,\ the 



Wisconsin glaclatlon, the drift and loessial strata ranging in depth from 95 

 to 300 ft., with an average depth of 200 ft. over the entire area. The county 

 Is divided Into six drainage areas Including the Sangamon Basin, the Kaskaskia 

 Basin, the Embarrass Basin, the Little Vermilion Basin, the Salt Pork Basin, 



and the Middle Pork l'asin. 



The sops of the county embrace upland prairie, upland timber, terrace, and 

 swamp and bottom-land soils covering, respectively, 92.2, L89, 2JSB, and 0.52 



per Cenl of the total area. The fertility COntenI and needs and methods of 

 management of the various v.^ls are discussed. 



The value of manure on Indiana soils, A. T. WlAWCKO and S. C. Jon&s 

 [Indiana Sta. Hut. 922 {1918), pp. -'". fig*. 6). -Field tests in progress at Lhe 



station sit 1890 and on six outlying experiment Holds for shorter periods of 



time are described. In which manure has been used in varying amounts and 

 on different crops grown continuously and In rotation. 



On the basis of the results obtained, it Is concluded that farm manures 

 are now worth twice as much as before the war. Crop Increases valued from 



$2 to $8, or more, per ton of manure applied were secured according to the 



fertility of the soil and the crops grown, while the average return on the 

 different experiment fields reported amounted to $5 per ton. Light applica- 

 tions made every 8 or 4 years are deemed much more profitable than heavy 

 applications at longer Intervals. Reinforcing manure with phosphates is also 

 recommended. The sources of waste ami loss in manure through Improper 

 methods of handling on the farm are indicated, and measures for conserving 

 manure discussed. 



The book of the Rothamsted experiments, A. 1 >. ll\ti. revised by F. J. 

 Russell {London: John Hurray, 1917, -'. ed., rev., pp. \i \-3S2, pi*. 8, ftp*. 

 S7). — This is the second edition of the work previously noted (EL S. K., 17, p. 



