NURSERY PRACTICE ON THE NATIONAL FORESTS. 25 
drills) , and length of time that the stock is to be left in the seed beds. 
The optimum density must be determined through experience. Too 
heavy stands make the stock spindly, and necessitate more seed, 
more work, and more grading than stands of the proper density 
(PI. VI). Very light stands produce seedlings of good quality; 
but, as the area is not fully utilized, the cost of the stock is greater 
than it need be. In Table 3 the densities striven for by the nurseries 
in the region indicated, as well as the season of sowing, are shown. 
The density of stocking can be regulated by the amount of seed 
sown. The density desired and the germination percentage of the 
seed being known, the number of seed to sow per square or per 
linear foot may be determined by use of the following formula: 
Number of seedlings desired per square foot or per linear foot + from 10 to 20 per cent. 
Germination percentage of seed. 
If germination is less complete or there is more loss in the seed 
beds when seed is sown at one season than at another, this will have 
to be given due consideration. The additional 10 to 20 per cent is 
to allow for poorer germination in seed beds than that secured in 
the tests and for losses after germination. To determine the weight 
of seed to be be sown per seed bed the foregoing formula would have 
to be multiplied by the number of square or of linear feet per bed and 
divided by the number of seed per pound of sample. 
