Studies oe Health in Potatoes. 
T T 
Figure 2.—Diagram illustrating the root habits of potatoes. 
tion tends to deeper root growth. A root cut off as at A tends to 
develop brandies running deeper. A specially rich spot of earth, or 
composted manure, stimulates an abundant feeding-root system, as 
at D. After the leaves shade the .^ntire ground and the weather 
becomes cooler the surface soil is filled with fibrous roots, as shown 
at C. For a full crop, it is important that this richest soil be com¬ 
pletely utilized at the end of the growing season. Crops that do 
poorly early in the season have the least chance to make good 
because they do not shade the ground as well. 
In relation to other roots, particularly those of sagebrush and 
alfalfa, we found that potato roots seem to gain nothing from the 
other roots while they are alive, nor before they decay. In recently 
plowed alfalfa land the soil is more tightly packed about the roots 
than elsewhere. Potato roots do not go down the alfalfa roots the 
first year, but the second year the alfalfa roots furnish both food, 
air and space, and when a potato root reaches a decayed alfalfa root, 
as at B, it goes on down for several feet, as to F, and even through 
soil which the potato root alone would not enter. If, in such heavy 
soil, there are sandy layers the potato roots enter them as at G. 
On the-dry land we found potato roots stopped by a dry sub¬ 
soil. The season of jqtt was one of scant moisture and at the time 
of the studies in 1912 the subsoil, though loamy, was so dry that 
the potato roots did not enter it, but were confined to the upper two 
feet, moistened by the rains of 1912. At Carbondale and Kersey 
we found potato roots stopped by clay. On the E. E. Edgerton 
mesa farm at Carbondale we found potato roots going less than two 
