452 EXPERIMENT STATION RECORD. 



and each tray is carefully wiped with a cloth and then weighed upon a torsion bal- 

 ance, which weighs accurately to one-tenth of a grain. After removing the lids the 

 trays are placed in a large drying oven, and there heated for from 18 to 24 hours, or 

 until the temperature in the oven becomes reasonably constant at about 110° C, 

 when the weighing is repeated, and from these two weighings and the weight of the 

 tray the per cent of moisture is figured, with the dry weight of the soil used as a 

 basis." 



The variations in the moisture content of fall-plowed, spring-plowed, and unplowed 

 land, and in soils under various crops and crop rotation, cultivated in different ways, 

 especially as regards depth and frequency, were studied by this method. The results 

 are reported in detail, but are somewhat inconclusive at this stage of the investigations. 



The mechanical analysis of soils, J. G. McIntosh (Chem. News, 90 (1904), No. 

 2333, p. 80). — Tests of the methods of mechanical analysis of Nobel, Schloesing, and 

 Masure are reported to show that they give very discordant results on the same 

 sample of soil. The author claims that "the data afforded by a mere mechanical 

 analysis of the soil tells nothing either to the chemist or farmer." 



Micro-organisms of soil and human welfare, T. J. Burrill (Science, n. ser., 20 

 (1904), No. 509, pp. 426-434).— -This is the presidential address read at the Buffalo 

 meeting of the American Microscopical Society August 24, 1904, and briefly discusses 

 the characteristics of soil micro-organisms and their relation to rock disintegration, 

 nitrification, and fixation of nitrogen alone or in symbiosis with leguminous plants. 

 The dependence of soil fertility and consequently man's prosperity and welfare upon 

 the activities of soil organisms is emphasized. 



The comparative nitrifying power of soils, S. F. Ashby (Jour. Chem. Soc. 

 [London], 85 (1904), No. 502, pp. 1158-1170). — This is a preliminary report on inves- 

 tigations made with a view to finding a trustworthy method for comparing the activity 

 of nitrification in different soils. The method employed in the studies here reported 

 consisted in taking a large sample of soil at a constant depth, drying and pulverizing 

 the sample to secure uniformity, seeding a very small quantity (0.2 gm. ) in a dilute 

 sterilized culture solution of constant depth, incubating at constant temperature 

 until nitrification had made moderate progress in the least active solution, and cal- 

 culating the results as parts per hundred of total nitrogen nitrified. 



The results show that the method gave reasonably concordant nitrifying power in 

 soil from different parts of the same field, that equal seedings from the same sample 

 had similar nitrifying power, that the loss of nitrogen by denitrification and volatili- 

 zation of ammonia during incubation was minimized, that the incubation period was 

 about 30 days, and that a comparative nitrifying power was found in the soils tested 

 which agreed with that which might be inferred from their known history. 



Some essential soil changes produced by micro-organisms, S. F. Edwards 

 (Michigan Sta. Bui. 218, pp. 25-30, fig. 1). — "The object of this bulletin is to review 

 simply and briefly the present knowledge of soil bacteriology in its relation to 

 agriculture with a view to emphasizing the close relationship between bacteriologic 

 principles and the common operations of tilling the soil." It explains the conditions 

 essential to bacterial activity and describes the processes of ammonification, denitri- 

 fication, nitrification, and fixation of nitrogen, as well as other changes brought 

 about in the soil by micro-organisms. 



Soil management, E. W. Hilgard (Science, n. ser., 20 (1904), -ZVb. 514, pp- 605- 

 608). — A review of three papers by F. H. King, published by the author with per- 

 mission of the Secretary of Agriculture, and containing reports of investigations 

 conducted while the author was connected with the Bureau of Soils of this 

 Department. 



A contribution to the study of the culture of alkali soils, A. Guyader 

 (Bui. Dir. Agr. et Com. [Tunis'], 9 (1904), No. 32, pp. 451-461). — A review of litera- 

 ture on this subject with applications to Tunisian conditions. 



