216 EXPERIMENT STATION RECORD. 



cent aluminum oxid. and constituted about 44.24 per cent of the total soil. The 

 conditions of their occurrence are said to indicate that they are of recent local 

 origin, and although several theories are advanced no satisfactory explanation 

 of the manner of their origin is given. Similar concretions were found in a 

 sandpit in a diluvial loess loam underlain by a strongly kaolinized leached out 

 porphyry, which in turn rests on diluvial sand. It is thought that these 

 originate from the precipitation in place of manganese, and iron in solution 

 coming from below. 



The origin of a limestone concretion found in the Rhine Valley is attributed 

 to the precipitation of leachings from adjacent limestone cliffs. 



The necessity for determining the water content of soil on the basis of 

 the soil volume, R. Kegel {Trudy Biuro Prikl. Bot. (Bui. Angeic. Bot.), 7 

 {IDUf), No. Jf, pp. 257-262). — Soil moisture determinations at different depths 

 and at different parts of each of several experimental plats showed no corre- 

 spondence between the quantity of soil moisture and crop development, owing 

 mainly it is thought to the varying specific weights of the soil. It is concluded 

 that to correlate more accurately soil moisture content and crop development 

 the determination of soil moisture contributing to crop development .should be 

 based not on the weight but on a fixed volume of soil. 



A study of the bacterial activities of virgin and cultivated soils, J. E. 

 Greaves {Centhl. Bakt. [etc.], 2. AM., U {WW, No. 11-17, pp. ^.J.M59).— A 

 study of the bacterial activities of virgin and cultivated soils from nine farms 

 in Utah, situated at various places within a radius of 45 miles, is reported. 



The soils varied in physical composition from a heavy clay to a fine sand, and 

 were well stocked with calcium carbonate and plant food elements with the ex- 

 ception of nitrogen. The number of organisms, the amount of nitric nitrogen, 

 and the nitrogen fixation were found to be twice as great in cultivated soils as 

 in virgin soils. Wheat soils contained greater numbers of organisms and more 

 nitric nitrogen than alfalfa soils, but nitrogen fixation was slightly greater in 

 the latter. Nitrogen fixation was greater in soils comparatively rich in com- 

 bined nitrogen than in those poor in organic nitrogen. Cultivation of the soil 

 increased bacterial activity and available plant food. 



It is thought likely " that a part of the increase in crops which results from 

 summer fallowing, disking, and the like is due to increased available plant food 

 of the soil brought about by increased bacterial activities. The various micro- 

 scopic nitrogen fixing organisms of the soil play an as yet unmeasured, but ap- 

 preciable part in the maintenance of the nitrogen content of the cultivated arid 

 soils. The abundance of Azotobacter present in the soil and the ideal condition 

 prevailing for their activity make it appear that it is this species that play 

 the greatest part in fixing the nitrogen." 



Bacteriological studies of field soils. — III, The effects of barnyard manure, 

 P. E. Brown {Iowa Sta. Research Bui. 13 {19U), pp. .i21-US) .—The work 

 here reported has been previously noted from another source (E. S. R., 31, 

 p. 121). 



To what extent can the results of fertilizer and variety tests be influenced 

 and thus lead to false conclusions? B. Rogalski {IUus. Landw. Ztg., 34 

 {19W, Nos. 43, pp. iOO, 401; 44, pp. ^07, //OS).— The various factors which 

 must be taken into consideration in planning and in drawing deductions from 

 the results of such experiments are discussed. 



Results of fertilizer experiments carried on in the years 1911-1913 at 

 Lauchstadt and Gross-Liibars, Schneidewind and D. Meyer {Mitt. Deut. 

 Landic. Gesell., 29 {1914), No. 28, pp. 406-409) .—Tests of various green manur- 

 ing plants (serradella, yellow and white clovers, peas, beans, and lupines) on 



