NURSERY PRACTICE ON THE NATIONAL FORESTS. 51 
large stock. For small stock a vertical wooden moldboard is used 
in place of the steel. This merely serves to push the trees away 
after they are loosened, but does not cover them. 
With the digger shown in Plate XIX the principle of operation 
is very simple. A wedge-shaped knife 7 feet long, 12 inches wide, 
and 6 inches thick in the rear is drawn under the beds at regulated 
depths. As the trees are loosened they are crowded out over the 
wedge by the forward movement of the implement and are picked 
from the soil in the rear. The digger is drawn by a horse-operated 
capstan and steel cable and travels at the rate of 6 feet per minute. 
The trees are removed in perfect condition. It works better with 
transplants than with seedlings, because the latter are sometimes 
covered with soil before they can be removed. 
All of these diggers loosen the soil to such an extent that the 
trees must be taken up very quickly; and since their economic rate 
of operation is considerably faster than transplanting, some extra 
labor is required to heel in the seedlings temporarily. 
Precautions must be taken to prevent the drying out of the roots. 
It is well known to nurserymen that conifers are quite sensitive in 
this respect, but laborers do not generally realize its significance. 
In semiarid regions the danger is especially great. Buckets, basins, 
or tubs partially filled with water are sometimes kept at hand, and 
as fast as the seedlings are dug their roots are immersed in these. 
All the soil, and it is thought some of the fine rootlets, are washed 
off by this practice. This has led to a different method at some of 
the nurseries. Boxes about 3 feet long by 2 feet wide are padded 
inside with moist burlap or with burlap over moist sphagnum moss. 
They also contain, fastened at one end of the box, several moistened 
burlap pads which are used to separate successive layers of trees. 
As the seedlings are dug they are placed in the boxes in layers with 
a moist pad between each layer and carried to the transplanting 
area. In this manner the roots are kept constantly moist, but are 
not washed. 
The importance of not subjecting the roots of conifers to ex- 
posure at any time can not be emphasized too strongly. Coniferous 
tops remain green for a long time after the roots are dead, and 
their appearance can not be taken as a criterion of the condition 
of the stock. An exposure of even 2 or 3 minutes, particular^ 
on a windy or very hot day, may prove fatal; and mortality in 
transplant beds or in field planting may be due to lack of care 
in this respect rather than to improper methods of transplanting 
or field planting. At the Boulder Nursery experiments in exposing 
seedlings of Douglas fir to the sun for periods varying from 3 
minutes to 4 hours resulted in a loss in the transplant beds of 5 
per cent when the exposure was for 3 and 6 minutes, of 8 per cent 
