236 Journal of Agricultural Research voi. ix, No. ? 
weather the globules of water soon disappear; but if the weather is cool 
and humid the droplets may be retained for one or two days. 
The samples for analyses were taken by scooping up a thin layer of soil 
from the brown spots two or three days after the irrigation water was 
turned off, but before the surface was disturbed by harrowing. The 
0L£77~ 
Fig. 16.—Diagram showing the nitrate content of the niter spots in furrow-irrigated soils. Season of 1916. 
amount of nitric nitrogen found in the niter spots or streaks after irriga¬ 
tion are shown in figures 16 and 17. 
The samples taken after the first irrigation show only a light accumu¬ 
lation of nitrates in the brown spots. At this time the brownish color 
characteristic of the niter spot was not abundant in any of the plots, 
