41 



the highest possible tonnage consistent with a high sugar con- 

 tent of satisfactory purity. This combination is best found 

 there in a good, strong, sandy loam, underlain by a plastic 

 light clay loam subsoil at a depth of 12 to 20 inches. Nearly 

 as good is a deep, fine, sandy loam extending to a depth of 3 

 feet or more. 



Without taking time for further illustration, the specific 

 cases of soil adaptation to crops already described will be 

 sufficient to show, perhaps, that many of our leading crops 

 have reached their highest development on special types or 

 conditions of soil. 



It may be worth while to note here that our natural forest 

 growth also indicates clearly that many varieties of trees suc- 

 ceed best on certain kinds of soil. The local name " black 

 walnut land " is still used where that hardy tree grows to 

 indicate a heavy type of soil. In southeast Michigan this is 

 the " Miami clay loam." The hickory thrives in the north- 

 eastern States on the heavier soils. Black walnut and hick- 

 ory are both deep-rooted trees. In the same region " hemlock 

 land " always indicates a sandy soil, and the hemlock is 

 not a deep-rooted tree. In the orchard districts of West Vir- 

 ginia the leading peach growers will not tolerate " white 

 oak " land, but a mixed growth of " rock oak and chestnut," 

 about one-third of the former and two-thirds of the latter, 

 indicates a soil which has been instrumental in making one 

 of the most famous fruit districts in the world. The rock 

 oak and chestnut growth indicates a soil somewhat stronger 

 than that of chestnut alone, as a better supply of moisture 

 is maintained ; when newly cleared it is more productive, 

 and even on old ground better results are secured from fer- 

 tilization. The subsoil is finer textured, that is, more clayey, 

 than the chestnut subsoil, but still is not so heavy as the 

 white oak soil. Yet on the latter some varieties of apples 

 thrive. Carrying a step further the matter of soil adaptation 

 to the different varieties of oak, it is a matter of common 

 observation that poor and thin soils often support only the 

 dwarfish black jack oak and the post oak. 



Shreve has found in his forestry studies in Maryland that 

 " the general distribution of the loblolly pine is determined 



