20 EXPERIMENT STATION RECOKD. [VoL 37 



Only in the last of these was there any accumulation of nitrate in the first 

 foot of soil, a much smaller amount occurring in the cropped soil and only 

 very small quantities under grass." 



Studies of north Idaho soils, J. J. Putnam {Idaho Sta. Bui. 92 {1916), 

 p. 9). — Ammonification and nitrification studies of two soils, similar to timber 

 soils, showed that " both with ammonium sulphate and blood as the source of 

 nitrogen the presence of 1 per cent of calcium carbonate greatly increases the 

 activity of the nitrifying organisms. The presence of 5 per cent of sawdust 

 greatly lessens the activity of the nitrifying organisms even when calcium car- 

 bonate is present. With blood as a source of nitrogen the presence of sawdust 

 greatly lessens the activity of the ammonifying organisms. When 2.5 per 

 cent of sawdust was used, 36.72 per cent of the nitrogen was transformed into 

 ammonia. When the amount of sawdust was increased to 5 per cent, only 27.84 

 per cent of the nitrogen was transformed to ammonia." 



The organic matter of the soil. — III, On the production of humus from 

 manures, R. A. Gortxeb {Soil Set., 5 {1917), No. 1, pp. IS). — In continuation 

 of work previously noted (E. S. R., 3G, p. 815), experiments conducted at the 

 Minnesota Experiment Station are reported on the increase of ammonia-soluble 

 humus brought about by adding powdered silk waste, powdered wool, (lour, and 

 alfalfa meal to moist sub.soil at respective rates of 500, 460. .50. and 200 gm. 

 per 7,500 gm. of subsoil, and allowing the mixture to undergo natural " huraifi- 

 catlon." Carbon, nitrogen, and humus were determlnetl in the original hiixture 

 and in the final product after remaining In a moist condition in the greenhouse 

 for one year. 



It was found that there was a decided loss of organlcf carbon from all of the 

 samples, ranging from a minimum loss of 18.4 per cent to a maximum of 55 

 per cent of the carbon originally present. There was likewise a loss of nitrogen, 

 but this lo.ss was not proportional to the loss of organic carbon, ranging from 

 5 to 26.5 per cent of the nitrogen originally present. There was a loss of humus, 

 the material dissolved from the leached soil by 4 per cent NH.OH. and this 

 loss appeared to be directly proportional to the loss of nitrogen. In three of 

 the four experiments no significant change was apparent In the materials 

 extracted by 4 per cent NH4OH from the unleached soil. In the remaining 

 experiment there was a loss of 60 per cent of the original materials. 



" These experiments furnish no evidence that an increase of soil humus Is 

 brought about by a specific humification. On the contrary all the evidence is 

 directly opposed to such a conclusion, and it appears altogether probable that 

 the maximum amount of ammonia-soluble material Is present in a .soil Imme- 

 diately after a green manuring crop has been plowed under and before the 

 humifying bacteria or fun,i:i begin their work." 



Eight references to literature bearing on the subject are appended. 



The loess soils of the Nebraska portion of the transition region. — VI, 

 The relative " rawress " of the subsoils, F. J. Alway, G. R. McDole, and 

 C. O. RosT {Sou Set., 3 {1917), A'o. 1, pp. 9-S6, pis. 9, figs. 4).— Pot experiments 

 conducted at the Minnesota Experiment Station with loess surface soils, de- 

 scribed In previous reports (E. S. R., 36, p. 421), and with the corresponding 

 subsoils fron) the second to the sixth foot, using corn, beans, clover, and alfalfa 

 to determine the relative " rawness" or infertility of the subsoils, are reported. 



It was found that the soils evidenced no rawness toward the Inoculated 

 legumes. " Eight successive crops of alfalfa gave almost as heavy yields on the 

 subsoils from the eastern half of Nebraska as on the corresponding surface soils. 



" From field observations on the loess soils of eastern Nebraska it Is evident 

 that the deep subsoils at depths of even 20 to 30 ft., both when the surface of 

 these Is simply exposed by gradltLg operations and when such excavateti 



