The Ammonifying Efficiency of Certain Colorado Soils. 7 
Samplf No. 5. 
Here we have another bearing orchard of probably twenty 
acres, seven of which had been killed by niter previous to 1911, and 
the trees from that portion had been pulled out. The land had*been 
planted to oats in the spring of 1911, but judging from the scatter¬ 
ing stubble which I saw in the fall, the original stand had been very 
poor. Many more trees were either dead or dying at this time, and 
the prospects were that the entire tract would be gone by the end 
of 1912. My sample, a sandy loam, was taken beside a badly 
burned tree in that part of the orchard where the injury was most 
^ctive at that time. The nitrogen recovered ,as ammonia with this 
soil was as follows: 
From cottonseed meal 38.63%; dried blood 36.78%; alfalfa 
meal 21.08%; flaxseed meal 20.10%. It will be seen from these 
figures that the yields from the alfalfa and flaxseed meals are much 
higher than those obtained with any other soil. Because of an un¬ 
avoidable delay, the ammonia determinations on this series were not 
made until after eleven days, and the prolonged incubation period 
will probably account for the increase obtained here. 
Sample No. 6. 
This soil presents a very interesting history. It comes from a 
forty, acre tract, twenty acres of which had been in alfalfa, and the 
remainder was bearing orchard. In 1907* barren spots began to ap¬ 
pear here and there in the alfalfa, and brown patches on the soil, 
indicative of niter, were observed in the orchard. It was not long 
before the trees commenced to die in a manner that we have since 
come to associate with excessive nitrates. Here, as we haye noticed 
so frequently elsewhere, a few trees in the innermost part of the 
01 chard succumbed first, and with these as a focal center, the trouble 
spread with such marvelous rapidity that by the spring of 1909 all 
of the alfalfa had been destroyed and fifty per cent, of the trees 
were lost. The year 1909 saw the remaining trees perish, save for 
parts of six rows on one side of the orchard next to a dtich. Dur¬ 
ing 1910, the three inside rows were killed, and the fourth and fifth 
were burning. During 1911 the fourth and fifth died and the sixth 
was burning. (Fig. 1.) I am sure I do not know where we could 
find a more beautiful illustration of the formation and spread of 
nitrates from a central point than is given by the regular succession 
in which row after row of trees went down before the approach! lg 
wave of niter. From 1909 to 1911, the orchard was a barren waste, 
where absolutely nothing would grow, not even the commonest weed. 
(Fig. 2) The Azotobacter flora had been exterminated entirely from 
the surface layers of this area, although soil taken near one of the 
surviving trees in row five next to the outside row mentioned above 
gave a vigorous growth of Azotobacter and a fixation of 12.4689 m. g. 
of nitrogen per 100 c. c. of mannite solution. - - 
When I visited this place in the fall of 1911 to secure my sample 
