SOILS — FERTILIZERS. 91 7 



The general conclusions of the author are as follows: (1) Soils differing 

 strikingly in origin, UKtrphology, and composition show in the majority of cases 

 no less marked differences in their absorptive capacity. (U) The peculiarities 

 of the absori)tlvo capacity of each soil are reflected to a certain degree, and 

 fretiuently very clearly, iu its finest particles (clay). (3) The finest group of 

 soil i)articles, the body of which presents a close combination of zeolitic clay 

 with organic-mineral substances, possess a high absorptive capacity sometimes 

 appn aching the maximum limit. (4) The absorptive capacity of a soil does 

 not show any parallelism with reference to ammonia, phosphoric acid, and 

 lime. Soils absorbing much ammonia may take up little lime and phosphoric 

 acid and inversely. A parallelism was observed only with reference to am- 

 monia and i)otash. The fine particles and the soils deprived of them re- 

 tain this peculiarity. (5) The maximum absorptive capacity with reference to 

 potash and ammonia is possessed by soils richest in humus — chernozem; with 

 reference to phosphoric acid, by soils rich in iron — red soils. The fine particles 

 and soils deprived of part of the latter retain these peculiarities. With reference 

 to lime the maximum absorption was shown by the I'ed soils, but this phe- 

 nomenon is not constant in its nature. (6) The presence of substances forming 

 the ortstein (organic compounds of iron) in podzols considerably heighten the 

 absorbing capacity of the podzol with reference to phosphoric acid ; in the fine 

 particles of the podzol this phenomenon is strongly accentuated. (7) The con- 

 clusion of Heiden, Krat, and others that no soil exhausts a solution completely 

 is not correc-t with regard to weak solutions of phosphoric acid. (S) Be- 

 tween the amount of anmionia absorbed by the soils and clays and their con- 

 tents of hygroscopic water there is a certain parallelism which is masked, how- 

 ever, by other factors in very poor soils (podzol) containing very little hygro- 

 scopic water. (9) Between the mechanical composition of the soils and their 

 absorptive capacity there is a certain dependence which is the more marked the 

 less it is masked by other factors. The clay and in general the mechanical 

 fraction less than 0.01 nmi. in diameter is of the greatest influence. 



The pulverization and exhaustion of the soil in black fallow culture, 

 S. Kii.zniNSKi ( Kliozijai/ntrd, JU06, \<>. 2-i; abs. in Zlun: Oiiidtn. Agron. [Rusft. 

 Jour. Expt. Landw.], 9 (1908), No. 2, p. 311).— The author calls attention to the 

 lowering of yields of winter cereals on black fallow as compared with the April 

 fallow and even with the May fallow, on the unfertilized three-course rotation 

 section of the Poltava Experiment Field. 



This lf)wering began to be observed from the year 1900, when the third cycle 

 of the rotation was commenced. Earlier, in the period ].SV>.5-1899. the winter 

 cereals on the black fallow gave the highest yield. The data for moisture in 

 the upiM'r layer of the s<jil show that in the period lS95-lStM> it was higher 

 under the winter cereals on the black fallow than in the April fallow, while 

 the reverse was the case in the period 1899-1904. The mechanical analysis of 

 the soil in the later period gave in the black fallow more silt particles and con- 

 siderably less clay particles than in the April fallow. The chemical analysis 

 showed more humus, nitrogen, and phosphoric acid in the April fallow than in 

 the black.' It was found that at the time of the cultivation of the fallow nitri- 

 fication was strongest in the black fallow but weakest in the spring. 



On the basis of these data the author supposes the diminution of the yield 

 of the winter cen-als on the black fallow to be due to the fact that, owing to the 

 intensified mellowing in the black fallow cultivation, the soil imdergoes more 

 weathering and pulverization. In consequence higher crops are at first ob- 

 tained on black fallow than on other fallows. Then as the .soil becomes ex- 

 hausted by such high yields and its physical i)roperfies deteriorate (due to 

 very tine pulverization), conditions arise which are unfavorable for th»' accumn- 



