the electrolytic bridge method, described in Bureau of Soils Bulletin 

 61, for accumulations of alkali salts, and this is carried further, if 

 for any reason it seems desirable, by an analysis of the individual 

 saline constituents in the water extract. 



The foregoing is substantially the procedure of the bureau in ex- 

 aminations of soil samples submitted by correspondence. 



It is necessary to bear in mind that the most thorough examina- 

 tion of a soil may reveal nothing of a deleterious nature or nothing 

 indicating that success could not be had with the crops adapted to 

 that kind of material, and yet these crops might fail if certain field 

 indications are ignored. Success is not possible if the drainage con- 

 ditions are not satisfactory, if the elevation and topography of the 

 farm are not suitable, if the methods of cultivation and cropping 

 are not efficient, and if the market demands and transportation facil- 

 ities are inadequate. Some of these factors, which leave nothing in 

 the sample that can possibly be revealed and others which may or 

 may not leave effects that could only be determined by the most re- 

 fined methods and after exhaustive research, are so important and so 

 much more easily determined through a field examination that con- 

 siderable space will be given their consideration. 



Local limitations as to yields of crops arise partly through mis- 

 control and partly through misadaptation of soils to crops. The 

 most common fault in the control of soils comes through the method 

 and means of cultivation. 



The equipment of a farm for the proper and efficient cultivation 

 of any particular soil type should be regulated by the grade of soil. 

 Soils ranging in grade from loams to clays require for their efficient 

 control a farm equipment of large teams, of heavy draft animals, and 

 correspondingly heavy tools and implements, with substantial and 

 commodious buildings. A silt loam is usually heavier to handle than 

 a loam, and a clay is usually heavier to handle than a silt loam, and 

 provision should be made accordingly. On the other hand, soils 

 ranging from sand to fine sandy loams require for their most efficient 

 control smaller teams, lighter animals, and generally lighter tools and 

 implements, and less commodious buildings. The heavier grades of 

 soil not only offer more resistance in handling, but they require deeper 

 and more thorough cultivation. Where a sand may be efficiently 

 cultivated to a depth of 4 or 5 inches, a silt loam or clay may require 

 8 or 9 inches in depth of cultivation. 



The kind of implements most efficiently used on the different grades 

 of soil and particularly on some of the different soil types should be 

 adapted to the physical character of the soil. A loose sand or sandy 

 loam should be worked with implements that tend so far as possible 

 to compact the subsoil, while a silt loam that tends naturally to Corn- 

 Car. 26] 



