190 



loam, fine sandy loam, loam, shale loam, silt loam, clay loam, clay, adobe, 

 meadow, and muck and swamp.* 



Snydert refers to " sandy," " clay," and " loam " as the terms " used 

 to designate the prevailing character of the soil." Sandy soils he classes 

 as those containing 90 per cent, or more of pure sand. He mentions fur- 

 ther, loam soils i.e., mixture of sand and clay; if clay predominates it is 

 a clay loam; if sand, a sandy loam. Dealing with the preference of cer- 

 tain crops for particular classes of soil, he supplements his classification by 

 mentioning the classes of soil which in a large number of cases and under 

 average conditions (e.g. normal supply of plant food and an average rain- 

 fall) have proved to be satisfactory crop producers. 



The better class of potato soils, according to him, are those which con- 

 tain about 60 per cent, of medium sand, 20 to 25 per cent, of silt, and 

 about 5 per cent, of clay. For fruit-growing purposes he recommends 

 soils containing from 10 to 15 per cent, of clay, and not more than 40 per 

 cent, of sand. He looks upon those as the strongest corn soils which con- 

 tain from 40 to 45 per cent, of medium and fine sand, and about 15 per 

 cent, of clay. Good grass and general grain soils should contain about 15 

 per cent, of clay and 60 per cent, of silt. For wheat production he dis- 

 criminates between three classes of soils : those of the first class contain 

 from 30 to 50 per cent, of clay; those of the second, about 20 per cent, of 

 sand, 50 per cent, of silt, and from 20 to 30 per cent, of clay ; to the third 

 class are assigned those soils which are composed mainly of silt, contain- 

 ing thereof usually 75 per cent., together with from 10 to 15 per cent, of 

 clay. 



It will be noticed from the above how great is the variety in the class 

 names applied by different investigators to the several classes of soil. But 

 an even greater variety exists in connection with the grouping of the dif- 

 ferent grades of particles which go to make up any one soil, and which, 

 when they preponderate, impart to that soil its special character. Such 

 terms as medium sand, fine &and, silt, and clay have been used above : not 

 only do investigators differ among themselves in the terms which they thus 

 employ for any one grade of soil particles, but very frequently one and the 

 same term has been applied to widely distinct grades. Snyder, for 

 instance, uses the term " fine earth " to indicate that portion of the soil 

 which passes through a sieve with openings \ mm. in diameter, and then 

 goes on to grade this fine earth as follows : 



Diameter of 

 particles. 



Medium sand '25 *5 mm. 



Fine sand '1 - "25 ,, 



Very fine sand '05 -- '1 ,, 



Silt -01 - - -05 



Fine silt -005 '01 



Clay below '005 



This, it may be observed, is exactly the grading adopted in the Gov- 

 ernment Laboratories here, and it is also employed by the United States 



* In the 1906 Soil Survey Field-book issued by the U.S. Department of Agriculture, 

 the following 1 1 classes are enumerated under the scheme of classification based on mecha- 

 nical composition of soils : Coarse sand, medium sand, fine sand, sandy loam, fine sandy 

 loam, loam, silt loam, clay loam, sandy clay, silt clay, and clay (pp. 17 and 18). 



f " The chemistry of Foils and fertiliser," 1899, p. 24. 



