Dec. 15,1925 
Studies in Western Yellow Pine Nursery Practice 1103 
from damping off and other causes, and a better development of the 
plants at the end of the season, when compared with the deeper 
cover. The contrasts are so marked that the use of the shallower 
cover can be unhesitatingly recommended for use with western 
yellow pine in all nurseries in this region, at least where artificial 
watering is possible. The best showing was, on the whole, made by 
the 34"i nc h and ^8-inch depths. A cover varying between these 
two, with an average of ^ inch, should be adopted as standard and 
be adhered to as closely as equipment and facilities will permit, in 
order to secure greatest economy of seed and space in raising desir¬ 
ab le p lants. 
While it may be difficult to secure and maintain an exactly uniform 
and minutely regulated depth of cover, owing to mechanical difficul¬ 
ties in applying the cover and because of the washing of surface 
particles in sprinkling the beds, it has been found possible, by the 
development (at the Savenac nursery) of a special machine for cover¬ 
ing, and by care in watering, to keep variations usually within 34 
inch and never more than 34 inch. This makes it feasible to regulate 
the depth of cover to a range which can be maintained in large scale 
practice and one within which best results in germination and 
survival may be obtained. 
PROCEDURE 
In the spring of 1912, western yellow pine seed, collected on the 
Bitterroot National Forest in 1911, was sown in the Benton Flat 
nursery and at the Savenac and Boulder nurseries. Depths of 34 
inch and % inch were used, and seed was sown in plots 2 feet square, 
each containing 500 seeds. Counts were made once a week and 
seedlings were pulled as counted,, thus restricting the record to 
germination alone. 
In 1913 the work was carried out with greater completeness. One 
bed in the Meadow nursery was thoroughly spaded and worked over 
until in a good condition for sowing. The bed was then divided by 
wood strips into two series of six plots each for use with six 
different depths of cover. In one series the plots were 2 feet square 
for broadcast sowing, and in the other they were 1 by 4 feet for drill 
sowing. Thus by duplicating the different depths of cover with the 
two methods of sowing it was possible to make a combined study of 
depth and method of sowing in the same bed so as to bring out facts 
in regard to each phase as well as their relation to each other. 
Fresh western yellow pine seed was used. It was collected and 
extracted at the experiment station the previous fall (1912). Sowing 
was done June 6, the comparatively late sowing being due partly to 
delay in getting the new nursery in shape for sowing and partly to the 
fact that the season of 1913 was from three to four weeks later than 
the average. About 375 seeds to the square foot were sown, or an 
amount of seed sufficient to produce an estimated stand of 200 seed¬ 
lings in each drill, or 200 to the square foot, on the basis of the green¬ 
house figures. The seed used for each plot was accurately weighed 
to within a limit of error of 4 seeds or 1 per cent of the good seeds 
sown, the same weight being used for all plots. Seed was sown as 
uniformly as possible. The drills were 3 inches apart, 4 drills to a 
plot, lengthwise. 
