536 



EXPERIMENT STATION RECORD. 



of mixing «a known quantity of soil with a known proportion of pure water and 

 determining the specific resistance Then an equal weight of the same soil is mixed 

 with a quantity of a dilute salt solution equal in volume to the pure water which 

 had heen mixed with the first quantity of soil. The specific resistance is again 

 determined. This will he lower than before. The amount of salt added to the 

 soil in solution is accurately known, as well as the effect it had on the resistance. 

 From this data the quantity of salt originally present in the soil can readily b9 

 calculated in terms of the. salt solution used." 



Tables are given for converting electrical resistances into conductivity, 

 for calibrating temperature cells, and for reducing the electrical resist- 

 ance to a uniform temperature of 60° F. 



On the denitrification processes, T. Ppeiffer {Ghent. Ztg., 21 

 {1897), Ao. 81, p. 841). — The author studied various forms of denitrify- 

 ing organisms isolated from horse manure and soil. A new form of 

 apparatus was used for studying the gas evolution of these organisms 

 in different nutrient solutions (Giltay's and nitrate-bouillon). The 

 activity of all forms ceased in an atmosphere of carbon dioxid. In 

 one culture of Bacillus denitrificans, admitting pure oxygen or air did 

 not effect denitrification. This is in direct contradiction to the obser- 

 vations of Ehrenberg and Stutzer. 



The influence of caustic lime and marl on the denitrification process 

 was studied both in culture media and in experiments with oats in pots 

 containing 27 kg. of soil mixed with 500 gm. of fresh horse manure. 

 The results were favorable to the use of these substances. 



The author concludes from his studies that the danger of loss by 

 denitrification is not so great as it was formerly supposed to be. 



Analyses of Wisconsin soils, F. W. Woll ( Wisconsin Sta. Rpt. 

 1896, pp. 303-305). — Analyses of 14 samples of soils collected in the 

 course of an agricultural survey of northern Wisconsin are reported. 

 The averages of all available analyses of soils of the same type in Wis- 

 consin, Michigan, and Minnesota are given in the following table: 



Average analyses of different types of Michigan, Minnesota, un<J Wisconsin soils. 



Prairie soils 



Clayey soils 



Loamy soils 



Dark sandy soils (potato soils) 



bai.dy soils 



Peaty soils 



Nitrogen. 



Per cent. 



0.26 

 .06 

 .16 

 .08 

 .06 



1.71 



The treatment of swamp or humus soils, F. H. King ( Wisconsin 

 Sta. Rpt. 1896, pp. 178-188, figs. 3). — There are large areas of swamp 

 lands in Wisconsin, some of which are being drained. It has been 

 observed in reclaiming these lands that certain spots, even on land 

 which is apparently in good condition, remain unproductive. The soil 

 of these spots is generally of a close, compact character. Analyses 

 showed that the amount of moisture present in them was not excessive. 



