62 



CLASSIFICATION OF RICE COUNTY TYPES ACCORDING 

 TO THE RUSSIAN SYSTEM. 



Having reported in detail the composition and properties of three 

 soil types, it will be of interest to consider their classification according 

 to the Russian system. The present and past climate of Minnesota 

 excludes the probability of any of these belonging to either Class I 

 ( Laterites and Red Earths) or Class IV (Semi-arid and Arid Soils). 

 Class V (Soils formed under an excess of moisture) are represented 

 only by the peat areas, which are not included in the present study, 

 and Class \'I (Alkali Soils), so far as now known, are entirely absent. 

 This leaves the three types studied to be assigned to either of the two 

 remaining classes, or partly to each, viz., Class IH (Chernozem or Ijlack 

 Prairie Soils) and Class H (Podzols, Gray Forest Soils, Brown 

 Earths and De^jraded Chernozem). 



The soils of Class HI, true chernozems, are characterized in the 

 surface layer by a content of organic carbon from 3.5 to 6.0 per cent 

 and of nitrogen from 0.30 to 0.50 per cent (21, p. 318), and a neutral 

 reaction while the soil just below the dark colored portion efifervesces 

 with dilute acids. The data in Table 64 illustrates the character of 

 typical Russian chernozems (21, p. 318). The soils of Class II, 

 degraded chernozems, podzols and Brown Earths, are lower in organic 

 carbon and nitrogen and are characterized by an acid reaction (16. 

 p. 88) of the surface layer. 



Table 64. — Organic Constituents in the surface foot (approx.) of Russian 

 cltcrnosein according to Kossorvitsch. 



Organic V^olatile Organic Carbon 



matter matter carbon* Nitrogen dioxide 



Source of sample per cent per cent per cent per cent per cent 



Orel, Mzensk Maloarchang.... 11.37 13.20 6.59 0.51 



Woronesh. Bobrowsk 11.73 14.67 6.80 0.55 0.00 



Ufa, Belebeiew 16 72 19.56 9.69 0.83 2.23 



Tobolisk, Tjukalinsk 10.82 14.22 6.27 0.48 0.00 



•Organic Matter -H 1.724. 



Of the Rice county soils (Table 65) the Fargo silt loam is clearly 

 a true chernozem, the organic carbon and nitrogen falling well above 

 the lower limits of the amounts of these constituents found in the 

 chernozems of Russia. The Carrington silt loam also would be placed 

 in this class if we considered only the proportions of organic carbon 

 and nitrogen but, considering also the acid reaction of the surface 

 layer and the non-calcereous nature of the subsoil immediately below 

 this, we must regard it as being in the early stages of degradation. 

 Table 65. — Organic Constituents in the surface foot of Rice County soils. 

 The data are averages of the two corresponding drift samples. 



Volatile Organic Carbon 



Matter Carbon Nitrogen Dioxide 



per cent per cent per cent per cent Keaction 



Fai-Ko Silt Loam 13.44 6.12 .50 .390 v. si. 



Carrington Silt Loam 9.07 4.29 .33 .076 med. 



Carrington Loam 5.25 2.25 .19 .077 med. 



Marshall Silt Loam 2.37 .21 .... med. 



With the Carrington loam this process has advanced still further, 

 placing the type clearly outside of the chernozems. The lower con- 

 tent of organic carbon and nitrogen and the acid reaction of the whole 

 three foot-section shows that it belongs in Class II, and since it both 

 lacks the characteristic podzol horizon (16, p. 68), and compared with 

 the Gray Forest Soils has a relatively high content of organic matter, 

 it is to be considered as degraded chernozem. 



