18 CIRCULAR 303, U.S. DEPARTMENT OF AGRICULTURE 



and that the trees which have persisted and have been productive 

 are on soils that are lighter brown in color and better drained. 



The way in which these dark-colored soils finger out into nearly all 

 parts of an area and extend into or across orchards is shown in a 

 tracing of a small part of the soil map of the Hilton area (fig. 4). 



In figure 5 is shown the plot of an old high-producing orchard of 

 Baldwin and Greening trees planted on Dunkirk silt loam but with 

 a narrow strip of Granby silt loam extending across it. On the 

 Granby soils, enclosed by dotted lines, nearly all the trees have died 

 or have been cut out. Some trees around the edge of this strip are 

 also unproductive. 



SOIL PROFILE AND ROOT PENETRATION 



In the commercial apple-growing districts of Virginia, there are a 

 few orchards, 65 years old or older, with trunks 5 to 6 feet in circum- 

 ference. Where examined, these orchards were found to be on deep 

 well-drained friable soils favorable for deep rooting and for moisture 

 conservation. 



In the apple-growing districts of the Ozarks, examinations have 

 shown 8 that trees planted on soils with open subsoils grow larger, 

 produce better, and live longer than trees planted on soils with tight 

 subsoils. 



To determine the depth and extent of rooting in the soils of the 

 lake-shore district of western New York, excavations were made and 

 the number, size, and position of the roots were plotted. 



For this purpose representative trees were selected, and excava- 

 tions 30 inches wide, 8 feet long, and as deep as roots could be found 

 were made, the center of the closer side being 16 feet from the trunk 

 of the tree. If possible the excavations were made where roots from 

 other trees would not enter them. 



As the excavation was extended downward, the side wall adjacent 

 to the tree was smoothed with a shovel. This was then laid off into 

 1-foot squares which were further divided into 6-inch blocks. The 

 size and position of the roots cut off in the side wall were then plotted 

 for a length of 6 feet, leaving 1 foot of space at either end of the exca- 

 vation for working room. Lines were also marked on the wall and 

 corresponding lines were drawn on a graph representing as nearly as 

 possible the soil horizons or soil layers as seen in the freshly cut wall, 

 these being indicated largely by the color of the soil. 



In this way a number of graphs were made of roots of trees growing 

 on the more important soil types of each group. A few of these, 

 believed to be representative of subsoil conditions and root penetra- 

 tion as found in this district, are shown in this circular. 



Attention has already been called to the relation between the dark- 

 colored poorly drained soils and missing or unproductive trees. The 

 nearly black color and granular structure of these soils at the surface 

 is well shown in figure 2, C. No orchards were found which had 

 been planted entirely on soils of this group, and where any consider- 

 able part of an orchard had been so planted it was found that nearly 

 all the trees had died. Occasionally, however, an isolated tree 

 was found in an area of this kind or along its edge. 



' Sweet, A. T. subsoil an important factor in the growth of apple trees in the ozarks. U.S 

 Dept. Agr. Circ. 95, 12 p., illus. 1929. 



