318 KXPKHIMEXT STATION RECORD. 



:«)(•!<, roKiiUiii;: rmm :i lucn- i ind (lisappc rnii-c of llic otlior bases. This 

 potash was foiiiiil to bo less solubli' in liyilrocliloric acid than that in the un- 

 weatheivd fot-iv. Tliere was a muc-li lai-f,'er jx'i-centa;;*' of silicic acid in the 

 weathered material than in tlic unweathered rock. 



The results indicate that the lower the aluuiimim content of the rocU-forni- 

 inj; minerals the fxroater their solubility. 



The author is of the opinion that the formation of kaolin takes place to only 

 a slijjht extent in the presence of humus acids. In the weathering of podzol 

 soils tlie same kind of chan^'os ^o on in the silicates as in moor soils. He sug- 

 gests that tlie formation of liardpan in such soils is due to the leaching down 

 of the liumus acids into the lower layers of the soil, where they are neutralized 

 l)y the bases j)resent. 



Sinular changes in silicates, due to the action of humus acids, occur in black 

 soils, but in such soils the action of the acids in forming difficultly soluble 

 compounds is masked by the presence of easily soluble salts in the surface soil. 



It was found that in calcareous soils the lower layers of the soil were en- 

 riched in bases at the expense of the upper layers. 



Investigations on the decomposition of various green manuring plants in 

 the soil, (). Le.mmeumann. A. Tazknko, and 11. Fischer (Ldiidir. Jahrh., SH 

 ilHO!)). Eniimzungab. 5, pp. 10J-1J6; abs. in Centbl. Bakt. [etc.], 2. AM., 25 

 (1909). No. 10-13, pp. 317, 318). — Pot experiments with serradella, rape, beans, 

 vetches, and lupines with and without the addition of straw, superphosphate, 

 and calcium carbonate are reported. 



The results showed that in most cases there was no loss of free nitrogen 3^ 

 months after tlie green manures had been turned under, although nitrogen had 

 evidently been lost in the form of ammonia. AVith lupines, rape, and beans 

 much less nitrogen Ix'came soluble in water than with vetches and serradella. 

 The greater the proportion of crude fiber in the green manuring plants the 

 smaller the amount of nitrogen rendered soluble. The addition of straw, 

 superphosphate, or calcium carbonate exerted no important influence on the 

 loss of nitrogen. The addition of straw, however, reduced the amount of 

 nitrogen rendered soluble. 



In vegetation exi)eriments the green manuring plants had very little effect. 

 T'nder the conditions of the experiments the crude fiber exerted a beneficial 

 influence on the action of the green manures. During an experimental period 

 of 28 days there was very little difference in the decomposition of the carbo- 

 hydrates of the various green manuring plants. 



Nitrification from the biological side, I. A. Makrinov (Vyestmk Bakt. 

 Af/hron. !:itantzil V. K. Fcrrcin, I'JOH, Xo. l.'/. pp. 132-119; abs. in Zhur. Opuitn. 

 Af/ron. {Russ. Jour. Expt. Lattdtc), 10 (1909), No. 3, pp. 1,27, 428).— From an 

 extended review of the literature of this subject the author concludes that : 

 (1) Organic matter in the form of humus, however abundant in the soil, does 

 not injuriously affect nitrification, but is rather favorable to it. (2) At the 

 same time this abundance of organic matter is not a necessary condition, be- 

 cause soils poor in humus can in the course of time produce intense nitrifica- 

 tion. (3) Humic substances, apparently, act favorably on the multiplication of 

 organisms ; and in general, the more the soil is provided with active organisms 

 and the more it is capable of carrying on a rapid nitrification the more humus 

 it contains. 



The author's own investigations also relate to the significance of organic 

 matter in the process of nitrification. With the aid of gelatinous silica obtained 

 by dialysis in jiarchment tubes, a nitrous micro-organism was separated from 

 two soils (one alkaline). This micro-organism is l.S fi long and 1.3 fi wide, 

 consequently is somewhat smaller than the St. Petersburg micro-organism of 



