SoOs 59 



difference between the surface and the subsoil is not great, 

 the subsral being in many cases just as fertile and meOaw 

 as the upper layer. In humid regirais, on the other hand, 

 the subsofl is often oatapact and, cm aoooont ai its lack 

 of aoation, seems ''dead" when brou^t to the surface. 

 Such soils scMnetimes require a number €i years to be- 

 come fertile. Sugar-beets, on account of their deep pene- 

 tratirai of roots and their hi^ air requirement, find their 

 best growth only in scHb having a subsoil omdition that 

 is favorable. Any hardpan layer is particularly detzi- 

 mentaL 



son, TESTUEE 



S(Mb vary greatly in the size of partides composing 

 them. ScMne are made iq> almost entirely of coarse parti- 

 cles; others are axnposed entirely of fine. Most scmIs, 

 however, contain some fine and scMue coarse grains, iht 

 nixdve number oi each determining the texture, which 

 cannot be modified by the fanner. Tbe texture of die 

 schI has a great influence cm the method ol tillage as wefl 

 as on a number of its pn^ierties, such as the water4MJd- 

 ing capacity, the circulatimi (tf air, and the availahiKty 

 of plant-food. These all hdp in determining the kind 

 of crop that should be grown. For example, peadies and 

 dierries thrive on a soQ having a coarse texture ; theanall 

 grains prefer a'' heavier " 9(h1; sugar-beets and most other 

 crt^ do best on soils of intermediate texture, sudi as the 

 loams. 



The various sizes of particles compoai^ the scmI have 

 beoi classified by the United States Department cl 

 Agriculture, Bureau c^ Soils, as fcJlows : 



