24 



CIRCULAR 303, U.S. DEPARTMENT OF AGRICULTURE 



m. 



a Baldwin apple tree 75 years old, 86 inches in circumference, grown 

 on a heavy type of the same soil. The root penetration of these trees 

 is shown in figures 9 and 10, respectively. 



Roots are very abundant in the heavier soils but almost entirely 

 wanting in the compact silt and very fine sand. At a depth of about 

 4 1 - feet a number of small roots have followed a thin layer of clay 

 into the compact silt and very fine sand. With this exception they 

 have penetrated the compact material scarcely at all. 



In places soils of the Collamer series of group 2 differ from the 



Dunkirk series of 

 group 1 principally in 

 the more strongly 

 developed gray and 

 mottled layer of the 

 upper subsoil. 



Although soils of 

 the Collamer series 

 have been developed 

 from water-laid and 

 stratified material, 

 the layers in the deep 

 subsoil as seen in 

 these excavations and 

 in figure 12 are in 

 many places distorted 

 and twisted. 



The cause of this 

 distortion of water- 

 laid material is not 

 definitely known. It 

 may have been caused 

 by the thrust of the 

 ice mass, by the melt- 

 ing of ice flows, by 

 slumping of the ma- 

 terial on slopes, or by 

 some other agency. 



Soils of group 1 

 have good under- 

 drainage so that the 

 subsoil is never sat- 

 urated for long periods of time. Compact layers which tend 

 to check or stop root penetration are not reached at slight depths 

 and are but slightly developed. The deep penetration of roots in 

 such soils is well shown in figures 13 and 14. m 



In fio-ure 13 is shown the root development of a Baldwin apple tree 

 35 years old, with a trunk girth of 67 inches, grown on Petoskey loamy 

 fine sand. The soil of this orchard has been deeply cultivated and 

 has received heavy applications of manure. The scarcity of roots m 

 the surface layer and their abundance and larger size in the B, C, 

 and D layers can be noted. The roots extend to a depth of 10 feet. 



i 



Figoje 12.— A deep roadside cut near Seabreeze showing the twisted 

 and crumpled subsoil layers found in places in the soils of group 2. 



