246 
Journal of A gricultural Research 
Vol. IX, No. 7 
taking place more rapidly than during the first two months after its ap¬ 
plication. There is a decrease in the nitrates from 6 to 30 inches in the 
manure plots, which 
iMiiMibigMKiBgE&gaftaaiaga 
/6-sa 
30 "- 4 £ 
42-54 
54-66 
66 - 761 
76-30 
60402 
Fig. 19.—Diagram showing the effect of rainfall January 7 to January 26, 
1916, on the distribution of nitrates in soils at Tordsburg, Cal. The 
black columns show the nitrate content of the soils on January 7 and 
the blank columns of January 26. 
is possibly due to the 
assimilation of the ni¬ 
trogen by the trees. 
Six sets of samples 
were taken from 
groves at Lordsburg 
on January 7, 1916. 
A second set of sam¬ 
ples was taken on Jan¬ 
uary 26. Each sample 
for analysis was made 
up of six borings, and 
the borings required 
for each set of samples 
were located as near 
each other as practi¬ 
cable. Between Janu¬ 
ary 7 and January 26 
there was a rainfall 
of 14.89 inches. The 
effect of the rainfall 
is shown in figure 19. 
Soil 1 contained only 
a small quantity of 
nitric nitrogen at the 
time the first set of 
samples was taken, but 
the amount contained 
was rather evenly dis¬ 
tributed to a depth of 
42 inches. On Janu¬ 
ary 26 the nitrates in 
soil 1 had been reduced 
to about one-fourth 
of the amount present 
on January 7. The 
amount of nitrates 
found below a depth of 
42 inches indicates 
that the rains between 
January 7 and 26 had 
carried the nitrates 
removed from the up¬ 
per layers of soil below 
a depth of 96 inches. 
