1918] SOILS — FERTILIZERS. 17 



" By means of the freezing point method the effect of application of soluble 

 salts and acids upon the concentration of the soil solution in the soil was also 

 studied. The results pertaining to the soluble salts show that the different 

 compounds employed have an entirely different effect upon the concentration 

 of the solution of the diverse classes of soil. In the case of the neutral salts 

 the solution of the agricultural soils was increased from 35 to 100 per cent of 

 their addefl strength, while in the case of the phosphate salts only a very small 

 portion of their concentration was added to the soil solution, amounting in the 

 majority of cases to only 10 per cent. All the salts, including the phosphates, 

 behaved the same in regard to the artificial substances, the quartz sand, kaolin, 

 burned soils, etc., as they all increased the concentration of their solution to 

 about the same degree. 100 per cent. The neutral salt solutions dio not behave 

 uniformly in the different types of soil, some of the salts produced the greatest 

 increase in concentrations in the sands and the smallest in the clays, while 

 other salts caused about the same degree of concentration in all the distinct 

 types of soil. 



"The different acids affected the concentration of the soil solution very dif- 

 ferently. Some of the acids augmented the concentration of *he solution of the 

 agricultural soils from 50 to 70 per cent of their added strength, others about 

 130 per cent, and still others only about 5 per cent. 



"The increase in concentration of the soil solution as produced by the appli- 

 cation of the salts and acids is due to the formation of new sub;:tances, the 

 depression of the freezing point of which is as great, greater, or less than 

 that of the original substance. In the case of the artificial substances such as 

 quartz sand, kaolin, burned soils, etc., both the original (Concentration and 

 composition of the salt solutions remained practically unaltered." 



Method of sterilizing and chloroforming soil used in studying chernozem, 

 S. Skalskij {luzh. Russ. Selsk. Khoz. Gaz., 1916, Nos. 1, pp. 7, 8; 2, pp. 6, 7/ 

 5, pp. 5-7; 7-9, pp. 9, 10; abs. in Internal. Inst. Agr. [Rome'\, Internat. Rev. 

 Sci. and Pract. Agr., 7 {1916), No. 9, pp. 1249-1253; Jour. Soc. Chem. Indus., 

 S6 {1911), No. 5, pp. 298, 299). — Experiments are reported with fallow cher- 

 nozem soil plowed in April, a chernozem soil cleared several year? previously, 

 and a three-year-old lucerne chernozem soil. 



"From each of these a surface layer (0-17.7cm.) and a layer immediately 

 below it (17.7-35.5 cm.) were taken, treated with various fertilizers, potted, and 

 sown with sterilized oat seeds. The first series (a) served as controls, the second 

 (b) was manured with potassium nitrate and magnesium sulphate and used to 

 determine the assimilable phosphoric acid content, the third (c) received po- 

 tassium dihydrogen phosphate and magnesium sulphate and was u>"ed to deter- 

 mine the assimilable nitrogen, the fourth (d) received a complete mineral 

 dressing of potassium nitrate, potassium dihydrogen phosphate, ani magnesium 

 sulphate, the fifth (e) contained soil sterilized by heating in an autoclave in 

 steam for one hour under 2.5 atmospheres, and in the sixth (f) chloroformed 

 soil was employed. Four plants were grown in each pot anl they were 

 watered from below with rain water so that the moisture content r emained at 

 the optimum throughout. 



"The plants died in some of the sterilized samples of soil. . . . The fertility 

 of (d) and (e) was about the same and much superior to the rest, (f) came 

 next, followed by (c), (b), and (a). To investigate the causes of the increased 

 fertility, the bacterial flora in the fallow soil was examined. The bacterial 

 numbers in (e) and (f) were incomparably greater than in (a), greater in the 

 shallow than in the deep soil, and greater on agar than on gelatin. In (f), 

 the bacterial increase and the higher fertility were accompanied by an enrich- 



