34 BULLETIN 47!), 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 \ 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 f-inch size 

 outlasts the 1-inch, because it is more pliable and kinks less easily. 

 At the Pocatello Nursery 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- 



