120 EXPERIMENT STATION RECOBD. [Vol.37 



increases in the production of other plant food constituents in an available 

 form." 



Further studies on suLfofication in five soils of varying texture and composi- 

 tion showed that " in the use of the free-sulphur-fresh-soil method for testing 

 the sulfofying power of soils, the Incubation period should be 14 days at room 

 temperature to give the most conclusive results. Ten days' incubation gave 

 the relative sulfofying powers of soils quite accurately, but the differences were 

 much more distinctive for the longer period. 



" Calcium sulphate in ordinary applications had no detrimental effect on 

 sulfoficatlon, but very large applications might decrease the rate of oxidation 

 of sulphur. Calcium carbonate in ordinary applications on acid soils increased 

 sulfoficatlon considerably and even in excessive amounts affected sulphur oxida- 

 tion favorably. Magnesium carbonate in small amounts increased sulfofica- 

 tlon, but in large amounts depressed it even below that in the same soil with 

 its acidity unneutralized. Magnesium carbonate and calcium carbonate in 

 combination exerted a beneficial influence on sulfofication when used in small 

 amounts. Larger applications, however, depressed the oxidation of sulphur. 

 The effects of the combined materials were less than that of the calcium car- 

 bonate alone." 



Nitrous nitrogen in irrigated soils, .T. E. Gkeaves, R. Stewart, and C. T. 

 Hirst (Soil Sci., 3 (1917), A'o. 2, pp. I.'f0-15^. pi. 1). — This paper, prepared at 

 the Utah Experiment Station, reports a study of the nitrous nitrogen content 

 of soils made in connection with studies of the influence of irrigation water 

 on the movement and production of nitrates in irrigated soils (E. S. R., 27, 

 p. 418). 



" The data reported represent some 800 determinations of the nitrous nitrogen 

 of a calcareous soil without crop, cropped to alfalfa, to oats and alfalfa, to 

 oats, to potatoes, and to sugar beets. The water applied to the soil varied 

 from none to 37.5 in. per acre yearly. 



" The nitrous nitrogen content of the soil was very low and was about evenly 

 distributed throughout the 10 ft. The total quantity found in an acre of soil 

 to a depth of 10 ft. varied from a trace ... up to 17 lbs. per acre. 



" No relationship was found to exist between the nitrous nitrogen and the 

 nitric nitrogen content of tlie soil. The application of irrigation water had no 

 appreciable influence upon the nitrous nitrogen content of the soil, [but] there 

 was a slight seasonal variation. ... In the alfalfa and the oat soils it was 

 highest in the .spring and decreased toward fall, while in the potato and the 

 corn soils it was lowest in sprinc: and increascil toward fall. In the fallow 

 the nitrous nitrogen was highest in midsummer. The greatest quantity of 

 nitrous nitrogen was found in the alfalfa soil during the spring, while the 

 least was found under the oats during midsummer. The application of manure 

 to the soil had no appreciable influence upon the nitrous nitrogen content of 

 the soil." 



Influence of humus forming materials of different nitrogen-carbon ratios 

 on bacterial activities, P. E. Brown and F. E. Allison (/oirn Sta. Research 

 Bui. S6 (1916), pp. 5-50). — Pot experiments on the influence of materials of 

 narrow and wide nitrogen-carbon ratio on the bacterial activities in Miami 

 sandy loam soil, low in organic matter, are reported. 



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

 maximum amounts for farm conditions and in a dried condition increased 

 ommonificatlon, nitrification, and azofication to a considerable extent. Horse 

 manure, cow manure, and rotted manure gave the greatest effect on ammonifica- 

 tion In most cases, although timothy hay surpassed the horse manure and 

 cow manure in the extent of Its effect in several instances. The oats, straw, 



