34 BULLETIN 479, U. S. DEPARTMENT OF AGRICULTURE. 
distribute the water so evenly, however, and unless closely attended 
and frequently shifted, they fail to distribute sufficient water to some 
portions of the beds, especially the corners. This is particularly 
true in seed beds with low frames, because these intercept the spray. 
Nevertheless, when well conducted, this method is quite efficient. 
The common lawn sprinkler with three or four whirling arms 
raised on an 8 to 16 inch standard has proved quite satisfactory. 
At the Wind River Nursery a wire edge formed on the wearing sur- 
face after a while and retarded the motion. Minute debris in the 
water clogs and stops the sprinklers, and they sometimes leak and 
wash the soil badly where they are placed. Their cost is from $1 
to $1.25 each. Another style of sprinkler which has proved satis- 
factory is made in a single casting and resembles an inverted bowl 
or a cone with one or two j or § inch holes at the apex. The sprink- 
lers throw out an inverted cone-shaped spray to a radius of 10 feet 
or more. They never clog and their cost is from 15 to 25 cents each. 
For convenience in dragging it around, each sprinkler can be mounted 
on a piece of plank about 10 inches square, with two sharp -edge 
runners on the lower side to prevent its working sideways when 
drawn over uneven ground in the paths between the beds. 
The possibilities of irrigating in seed beds before germination 
have not been determined for all conditions. At the Pocatello Nurs- 
ery subirrigation from ditches 3 feet apart was tried. It was found 
to be satisfactory with western yellow pine but not with Douglas fir. 
The beds could not be kept moist enough to induce good germina- 
tion of the latter species. At present sprinkling is followed at all 
Forest Service nurseries when watering is necessary during the pre- 
germination period, and it is thought that this is preferable to irri- 
gation, whose general practicability is very doubtful. 
At a number of nurseries cotton or canvas hose is considered 
superior to rubber. Second-grade cotton hose lasts two or three 
years, or about the same as rubber hose: it is much lighter and 
easier to handle than the latter: it does not damage the stock so 
badly if dragged across the beds and is cheaper. The J-inch size 
outlasts the 1-inch, because it is more pliable and kinks less easily. 
At the Pocatello Xursery a crack-proof rubber hose is used and gives 
very good satisfaction. 
LENGTH OF TIME REQUIRED FOR FULL GERMINATION. 
The length of time required for full germination can scarcely be 
given accurately, because it varies markedly with different soils, 
different methods of nursery practice, differences in the quality or 
source of the seed, and variations in the climatic factors. The ap- 
proximate length of time after spring sowing necessary for practi- 
