12 The Colorado Experiment Station. 
There is nothing in the results obtained by the ordinary agri- 
cu uia analyses of this soil to indicate anything unusual unless 
followed • Ttf amo “ nt of total nitrogen present. The method 
v ° r '^, n tbese anaI yses was the conventional one, digestion with 
hydnc chlorid sp g. 1.115, etc., and the nitrogen determined by 
v'o mod ! fied for the determination of nitric acid 7 
scmned 5 off ^ fil ' St , f °° t of ? 01 l fronl which the surface portion was 
scraped off in order to obtain the soil without incrustation of 
eftloi esced salts, and we have, as shown by the aqueous extract of 
and third fo a / T ark f bI M S n aI - amount of Crates while the second 
and third toot show decidedly increased quantities. The third foot- 
contains only a little less than the top two inches but is relatively 
11 y one-sixth as rich. We have for the top two inches 2,2 S7 
pounds, for the next foot 528 pounds, for the second foot mr> 
lieve thaTtl t f °, 0t ^’° 53 pounds per acre - 1 d ° not be- 
eve that the nitre m the third foot of soil participates largely in 
sav within’'t t ! le f tre f “ nless * be brou ? ht nearer to the surface, 
say within two feet of the surface, by capillarity or some other 
a a ent so that we cannot take this third foot into our reckoning 
except as a possible source of nitrates. The top twenty-six inches 
, . 11S - so '’ 10we ver, contained at the time the samples were 
taken, in May, a little better than two tons of sodic nitrate a 
comparatively moderate quantity, provided that these salts were 
not concentrated within the feeding zone of the roots. But even 
as the case stands, there is, assuming 80 trees to the acre’, fiftv 
1 oiinds of sodic nitrate to the tree, taking the soil to the depth of 
twenty-six inches and supposing that the succeeding foot with 
twenty-five pounds more for each tree does not in any way enter 
ito the pioblem. I do not know how the amount of nitrates 
caned during the ensuing season, but, if they increased in this 
soil as they were observed to do in some others, the a^o-re^ate 
amount present during the season must have been at least twice as 
gieat as that given but, be this as it may, no trees occupying a 
continuous area about the point where these samples were taken 
f iet cvi m the next four months in the same manner as that in 
n ’n Lrf f T po , ,soned with sodi c nitrate and as thousands 
amo, r A ln - a '! ncher 111 nItr ?‘ es > died - Th ^ question of the 
amount of nitrates necessary to kill apple trees would be an in¬ 
teresting one to answer but it is not the object of this bulletin. 
E C - aie also othe f. questions involved, for instance, to determine 
e maximum quantity of nitrates available to trees in such lands 
at any one time for it is evident, that if a fatal quantity were 
to Hlfd f ° r °w y , a uT dayS ’ perhaps one da 7 > it might suffice 
to kill them. We killed a tree m four days. Again it would be 
interesting to know whether a tree, say 15 years of age, would 
tolerate more saltpetre in September than in April, May or June, 
