720 EXPEEIMENT STATION RECORD. 



potash rendered soluble through displacement of that element by the lime of the 

 gypsum." 



The results reported show that an application of 472 gm. of gypsum resulted 

 in an increase of potash in the drainage water amounting to 3.75 gm. equivalent 

 to 198 lbs. per acre. With burnt lime only 9 lbs. per acre was i-emoved in the 

 drainage and there was a like loss in case of ground coral. The solubility of the 

 phosphoric acid of the soil varied somewhat with the different forms of lime 

 added, but the amounts were in every case very small, the largest amount being 

 found in the drainage water of the check lysimeter, the smallest in the lysimeter 

 to which gypsum was applied. 



Note on an apparent secular change in the Rothamsted drain gages, 

 E. J. Russell (Jour. Agr. ScL, 2 {1901), 'No. 1, pp. 29-3Jf, f}<i. i).— This article 

 discusses a question raised by observations reported in a previous article by 

 Miller (E. S. R., 18, p. 116). 



An analysis of observations with drain gages of different depth " seems to 

 point to a secular change in the drain gages resulting in an increased evapora- 

 tion of water. It is suggested that the change is brought about by the diminu- 

 tion of organic matter in the soil of the gages and the action of rain in washing 

 out the finest particles." 



Chemical and bacteriological soil studies, T. Remy {Landic. Jahrb., 35 

 (1906), 8up. Ji, pp. 1-62, pgs. 2). — Field, pot, and laboratory experiments with 

 two unproductive acid soils compared with one which was of good quality and 

 of slightly alkaline reaction are reported in detail, the object of the experiments 

 being to determine the cause of the unproductiveness of the soils. For this 

 purpose a careful study was made of the physical, chemical, and bacteriological 

 properties of the soils. 



The general conclusions reached were that the presence of free acid, deficiency 

 of lime, and a consequent low bacterial activity were the most pronounced 

 characteristics of the abnormal soils, and that when these conditions were cor- 

 rected the injurious effects on plant growth were removed. In these soils lime 

 acted less as a plant food than as a neutralizer of acidity. 



Methods of bacteriological investigation of soils, III, F. Lohnis and A. E. 

 Parr (Ccuthl. Bakt. [ctc.^, 2. AM., 17 (1906), Xo. l>i-16, pp. 518-.528, fig. 1).— 

 Experiments to test the putrefactive capacity of soils as described by Remy, 

 Wohltmann, Fischer, and Schneider under different conditions of season, tem- 

 perature, moisture, and food supply are reported, the general conclusion being 

 reached that there is no such thing as a general putrefactive capacity of soils, 

 but that this differs from time to time under the varying influence of season, 

 temperature, and moisture content. Other investigations which bear out this 

 conclusion are briefly reviewed. 



On the occurrence and distribution of Azotobacter chroococcum in dif- 

 erent soils, II. It. Christeiwsen {Centhl. Bakt. [rf<:\. 2. Aht.. 11 {1906), Xos. 

 3-4, pp. 109-119, iigs. 2; 5-1, pp. 161-165, figs. 2: 11-13, pp. 318-383).— As a 

 result of a series of studies the author conchides that the occurrence and dis- 

 tribution of Azotohacter chroococcum in different soils is determined largely 

 by the basicity of the soil, namely, its calcium carbonate content. The growth 

 of Azotobacter in a mannite and potassium phosphate solution inoculated with 

 a definite amount of soil furnishes an index of the calcium carbonate (also 

 magnesium carbonate) content of the soil. The test can be made more con- 

 clusive by adding to the cultui-e solution a small amount of Azotobacter culture 

 in addition to the inoculating soil. 



In like manner an indication of the content of phosphoric acid easily assimi- 

 lable by Azotobacter can be obtained by using a culture solution which con- 

 tains only potassium chlorid and calcium carbonate in addition to mannite. 



