536 



EXPERIMENT STATION RECORD. 



marked. On the other hand, light cultivation of the surface soil appeared to hasten 

 drying out. The evaporation from the uncultivated soil was about the same as from 

 that lightly cultivated, but it showed the advantage of absorbing more water in 

 winter. 



Oxidation in soils and its connection with fertility, E. J. Russell {Jour. 

 Agr. Sci., 1 (1905), No. 3, pp. 261-279, Jigs. 2).— Previous studies by Deherain, 

 Demoussy, and Wollny on oxidation in soils have been based on measurements of 

 the carbon dioxid produced by soil kept at constant temperature in a given volume 

 of air. The author reports studies based upon measurements of the actual oxygen 

 absorbed. 



The apparatus used consisted of "a flask of about 100 cc. capacity with two tubes 

 sealed into its neck. One of these (A, fig. 1) is bent at right angles and terminates 

 in a bulb B; higher up is the narrower one, C, of about 

 4 mm. diameter, also bent at right angles, but open at the 

 end. A weighed quantity of the air-dried soil is intro- 

 duced into the flask, a definite amount of water is added, 

 and the neck of the flask is either sealed up or closed 

 with a very well-fitting rubber cork. Potash solution 

 (1 KOH : 2H 2 0) is run into B by the little side tube D, 

 which is then sealed, and the end of C is dipped under 

 mercury, thus converting it into a gage. The apparatus 

 is now placed in a water-bath at constant temperature, 

 oxygen is absorbed, and doubtless a complex reaction takes 

 place, but the only gas likely to be set free from ordinary 

 soils is carbon dioxid, and this is so rapidly absorbed by 

 the potash that at any given moment the quantity present 

 in the first state is negligible. 



"The absorption of oxygen is indicated by the rise of 

 mercury in C, and from a measurement of the height of 

 the column above the surface the amount of oxygen 

 taken up is readily found. A cathetometer and milli- 

 meter scale are used for this purpose." 

 By this means the author studied the relation of various factors, such as quantity 

 of soil, moisture content, lime and calcium carbonate content, horizon of soil (surface 

 soil or subsoil), sterilization, and age of samples to oxidation. The rate of oxidation 

 in a number of soils of known but varying fertility was also investigated. 



The significance of the results is somewhat fully discussed and the following con- 

 clusions are drawn: 



"(1) The rate at which oxygen is absorbed by a soil can be easily and accurately 

 measured by the method here described. 



u (2) The rate increases with the temperature, the amount of water (up to a cer- 

 tain point), and the amount of calcium carbonate, and is favored by the conditions 

 obtaining in the surface soil as opposed to those in the subsoil. 



" (3 ) These are also the conditions favoring fertility. It is found that with different 

 soils of the same type the rate of oxidation varies in the same way as the fertility, 

 and may be used to measure it. Pasture soils are at present excluded, however. 



"(4) It is suggested that the oxygen absorbed measures the total action of the 

 micro-organisms, which, by producing enzyms and in other ways, hasten decompo- 

 sition in the soil. Plant food is thus produced, and the general conditions are ren- 

 dered more favorable for plant life. Ceteris paribus, the more rapid these changes 

 the more productive the soil will be." 



On the fixation of ammoniacal nitrogen by zeolites in the soil, T. Pfeiffer 

 and A. Einecke {Mitt. Landw. Inst. Breslau, 3 (1905), No. 2, pp. 299-310).— Experi- 

 ments were made with barley grown in glass vessels holding about 4,000 gin. of sand to 



Fig. 1.— Apparatus for meas- 

 uring the oxidation of soils. 



