The Fixation of Nitrogen. 79 
The only new thing that I have noticed during the past year 
in the deportment of these dying trees was their tendency to come 
into bloom in September and later. Sometimes a tree would put 
out quite a sprinkling of bloom. 
The question of concentration of nitrates has also been sug¬ 
gested. I had this question in mind when, in Bulletin 155, I re¬ 
ferred to the popular idea that the irrigating waters bring the 
black alkali” to the surface, and discussed the fact that some 
seepage waters issuing from certain shale banks contain significant 
quantities of nitrates. It was then shown that the shales contained 
no 11101 e initiates than could be readily accounted for by assuming 
their origin to be in the soils of the mesas above them, which as¬ 
sumption is suggested by the occurrence of areas which are very 
rich in nitrates on various parts of these mesas. Case 19 in which 
we find a very considerable number of such occurrences stretched 
along for a distance of probably five miles, is one in point. This 
ai ea lies above and extends southward from the point where the 
shale sample showing 0.03 percent of nitrates was taken. The 
intensity of the fixition or fixation and nitrification which has taken 
place in this area is indicated by the analyses given in connection 
with this case. W hile many of these occurrences made their first 
appeal ance in 1909 an d 1910 , over 2.0 percent of nitrates was 
found in an alkali collected on this mesa in 1907 and the aqueous 
extract of a soil sample taken the same year, 1907, contained nitric 
acid equivalent to 6.00 percent of sodic nitrate calculated on water- 
soluble or nearly 0.40 percent calculated on the air-dried sample. 
It is evident that leaching from the shales cannot possibly account 
for the occurrence of nitrates in the soils many feet above them. A 
similar argument applies to all of the geological formations occur¬ 
ring within the affected territory, i. e., they are wholly inadequate 
to account for the observed occurrences which are found above as 
well as below the various strata which might be taken as illustra¬ 
tions; in other words, the occurrences are wholly independent of 
the geological formations. 
It may be further mentioned that no other occurrences of 
nitrates have been found either in excavations, borings or elsewhere 
which might be considered the source of any of the nitrates. Again 
as previously urged, the general distribution of these nitrate patches 
requires for its explanation the existence of some very widely dis¬ 
tributed source or generally occurring cause. 
The fact that these nitrate spots are generally associated with 
wet land has led to the idea that the ground and even ditch waters 
may be accountable for them and consequently that drainage will 
obviate the trouble. It would in some cases be of decided benefit 
to drain the lands, and might possibly change the location of the 
nitre area by changing the area in which the condition of optimum 
