216 EXPERIMENT STATION RECORD. [Vol.35 



Oat plants assimilated only about 10 per cent of the phosphoric acid dis- 

 solved by 1 per cent hydrochloric acid, while with potassium the results agreed 

 much more closely. Water saturated with carbon dioxid dissolved much less 

 phosphoric acid than was asssimilated by oats in the same soil. In this case 

 the difference is attributed to the presence of organic acids in the roots, to the 

 dissolving action of manurial salts, and to disturbances in the equilibrium of 

 the soil solution. It is thought that the potassium fixed by absorption in soils, 

 as estimated by Kellner, can not be the only source of potassium available to 

 plants. While it was found that neither analysis of plants nor soil analysis, 

 as employed, is suitable for establishing the amounts of nutrients in soils, it is 

 considered liliely that useful indications will be obtained by ascertaining the 

 maximum amounts of nutritive substance which give increased yields. 



Carbon and nitrog-en changes in the soil variously treated: Soil treated 

 with lime, amnibniuni sulphate, and sodium nitrate, R. S. Pottee and R. S. 

 Snyder (SoU SoL, 1 {1916), No. 1, pp. 76-94, pl- 1, ftffs. 2).— The work of others 

 bearing on the subject is briefly reviewed, and pot experiments conducted at 

 the Iowa Experiment Station to determine the influence of additions per acre of 

 3 tons of calcium carbonate, 1,285 lbs. of sodium nitrate, 1,000 lbs. of am- 

 monium sulphate, and of combinations of calcium carbonate with each of the 

 nitrogen fertilizers in the amounts noted, on nitrogen losses, carbon dioxid 

 evolution, and on changes in the ammonia, nitrate, nitrogen, and carbonate 

 contents of an acid silt loam soil low in organic matter, are reported. 



It was found that " for all the soils except those treated with both ammonium 

 sulphate and lime, about 0.3 lb. of ammonia nitrogen was given off in 12 weeks. 

 If kept up throughout the year, this would mean a loss of a little over a pound 

 per acre in a year, an insignificant amount when compared to that lost by leach- 

 ing, cropping, etc. The loss from the soils treated with both lime and am- 

 monium sulphate was about ten times as high for the period of the experiment, 

 but it is not at all probable that this rate would be held for a very long period 

 after the application of the sulphate. Therefore, . . . the danger of loss of am- 

 moniacal nitrogen from the soil of the type used is practically negligible. In a 

 general way, the total nitrogen determinations show there is a smaller loss or 

 a greater gain of nitrogen for the limed soils than the corresponding unlimed 

 soils." 



The results with reference to the amounts of carbon dioxid evolution were 

 inconclusive and the experiment is being continued. 

 A list of 22 references to literature bearing on the subject is given. 

 The influence of some common humus-forming materials of narrow and 

 of wide nitrogen-carbon ratio on bacterial activities, P. E. Brown and F. E. 

 Allison (Soil Sci., 1 (1916), No. 1, pp. -^9-75).— Experiments, conducted at the 

 Iowa Experiment Station, with a slightly acid sandy loam soil low in organic 

 matter content to determine the influence of applications per acre of 15 tons 

 of each of horse, cow, and rotted manure; 2.5 tons of oat straw; 3 tons of 

 corn stover ; 2 tons of timothy hay ; and 4 tons of each of cowpea and clover 

 hay, on ammonification, nitrification, and nitrogen fixation, are reported. 



It was found that "application of the common humus-forming materials in 

 maximum amounts for farm conditions and in a dried condition increased 

 l)acterial activities, ammonification, nitrification, and azofication to a consid- 

 erable extent. Horse manure, cow manure, and rotted manure gave the 

 greatest effect on ammonification in most cases, although timothy hay sur- 

 passed the horse manure and cow manure in the extent of its effect in several 

 instances. The oat straw and corn stover had a lesser effect than the manures 

 and the legume hays, clover, and cowiieas showed the least effect on ammoni- 

 fication of any of the materials used. 



