RUSSIAN SOIL INVESTIGATIONS. 811 



small quantities. As long as the chernozem preserves its natural 

 g-ranular structure the high percentage of fine particles has compara- 

 tively little influence upon its relation to water, but in cultivation under 

 the climatic conditions prevailing in the steppes of southern Russia 

 these soils to a lai-ge extent lose this structure and consequently pre- 

 sent the properties of fine porosity, high capacity for absorbing and 

 retaining water, and low permeability. With irregular rainfall fol- 

 lowed by droughts the moisture of the surface soil has been observed 

 to decrease to t! per cent (one-seventh of its water capacity), and the 

 soil dries and hardens, resulting occasionally in serious failures of 

 crops. 



The chernozem of Siberia has not been very fully studied. Analysis 

 shows that it contains from 5 to 11 per cent of humus and from 0,28 

 to 0.6 per cent of nitrogen. In the eWey types there is from 15 to 25 

 per cent of zeolites, 7 to 10.5 per cent of alumina soluble in sulphuric 

 acid, and 0,16 to 0,2<S per cent of phosphoric acid. The soils of the 

 Amur prairies are generally richer in humus than the ordinary cherno- 

 zems of Russia. Soils of the chernozem type are found alternating 

 Avith alkali lands and sandy soils in Banat and in the plains of eastern 

 Hungary, which are separated by the Carpathian Mountains from the 

 steppes of southern Russia, 



The chernozem zone also embraces a considerable part of the United 

 States. The soils of the humid prairies in Wisconsin, Minnesota, 

 Iowa, Missouri, and other States are quite similar in character to the 

 chernozems of the Amur region. In States such as the Dakotas, Mon- 

 tana, Nebraska, Kansas, and Arkansas, where the rainfall is deficient, 

 the soils are similar to the ordinary and the chocolate colored cherno- 

 zems of the steppes of southern Russia, In the more strictly arid 

 States, such as Arizona, southern California, etc., are found analogues 

 of the chestnut and light brown soils of Russia. 



It is of interest to note that there is a southern chernozem zone 

 represented b}' the soils of the pampas of Argentina. Especially fine 

 examples of this type of soil are found in the Province of Entrerios. 



Gray forest ^r;/^*'.— Under this name are included the soils of the 

 wooded steppes, adjoining the chernozem or even penetrating" far into 

 the region of chernozem, but which have been modified b}' forest veg- 

 etation. They merge by a gradual transition into chernozem on the 

 one hand and peaty soils or podzols on the other. They extend in a 

 narrow, rather regular, not alwa^'s continuous belt across central 

 Russia from the governments of Lublin and Volinsk on the west to the 

 basin of Kama and Viatka on the east. In the chernozem zone they 

 are found usually along the rivers and valle^^s, where the soils are well 

 drained and free from alkali. The observations of soil experts and 

 geobotanists show concordantly that fine grained soils, which possess a 

 great capacity for humidity and a low degree of permeability, and those 



