38 The Colorado Experiment Station 
taken from these vertical sections, decreasing rapidly with depth, 
and in case of number 7, surprisingly low for our soils. 
In regard to the ground-waters collected from these various 
holes, we find a very great variation, indeed, just as great as we 
find in the vertical or lateral distribution of the nitrates and other 
salts. I have already stated the chief features of the ground-water 
obtained from Hole No. 1. The second sample of giound-watei 
taken from this sixth of an acre was taken from Hole No. 4. The 
water-plane was 4 feet 2 inches below the surface. The three-inch- 
sample of surface-soil contained 52.9 p. p. m. nitric nitrogen. The 
foot terminating at the water-plane, contained 57 *° P- P* while 
the intervening sections varied 3.5, 12 and 32 p. p. m. The total 
solids in this ground-water were 18,557 p. p. m. and the nitric nitro¬ 
gen 318.8 p. p. m. The other sample of ground-water carried 13,- 
258.0 p. p. m. water-soluble with 441.5 p. p. m. nitric nitrogen, 
while the surface-three-inches of soil carried 18.0 p. p. 111. nitric 
nitrogen, which at a depth of 55 inches had fallen to 1.5 p. P- m . 
The water-plane at this time was 8 feet 7 inches below the surface. 
This same land was brown in 1911 and the trees died. These facts 
even do not convey a full idea of the uneven distribution of the 
nitrates in this soil. We have seen that we can pick aieas of one 
sixth of an acre, so that they will show wide variations. We have 
further shown in this single piece of land the same thing that we 
have used other individual pieces to show, i. e., that there is no . 
connection between the ordinary alkali and the nitrates. The ver¬ 
tical distribution of the nitrates, as exhibited by the nineteen ver¬ 
tical sections made of this land, is certainly perplexing. We find a 
large amount in the surface-soil of one section with the water-plane 
four feet nine inches below the surface. The nitric nitrogen de¬ 
creases rapidly in this section from 423 p. p. m. of the air-dried soil 
to less than one part. This difference is very great as becomes more 
apparent on calculating this nitric nitrogen to the sodic salt. When 
we find 2,538 p. p. m. in the surface three inches and less than 
one part in the lowest foot taken. The ground-water taken 12 hours 
after the trench was dug contained only 4 p. p. m. of nitric nitrogen 
or as sodic nitrate 24 p. p. m. This sample of water should have 
been taken when the hole was first opened and should not have been 
allowed to stand. We have in the surface-portions of this, soil 
large amounts of nitrates and in the ground-waters only small 
amounts and in the intervening soil still less, in fact, as good as 
none. These facts may be remarkable, but this is the way we found 
them. There was no incrustation on this soil. The ground-water 
carried 9,788 p. p. m. of total solids. If we assume that these 
2,538 parts of nitrates, calculated as sodic nitrate for convenience. 
