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BACTERIOLOGICAL STUDIES OF THE FIXATION OF 
NITROGEN IN CERTAIN COLORADO SOILS. 
By Walter G. Sackett. 
Somewhat over a year ago, Dr. Headden called my attention to 
the extremely large quantities of nitrates present in certain Colorado 
soils, stating at the time that these nitrates were frequently associated 
with a brown discoloration of the soil, and that this color was often 
confined to well defined areas varying in size from three feet in di¬ 
ameter to an acre or more; furthermore, that these so called “brown 
spots” were not fixed, inert quantities related to some recognized geo¬ 
logical formation, but that they were alive, and in the process of mak¬ 
ing as evidenced not only by the rapid progress with which the then 
existing spots were spreading, but also by the almost continual appear¬ 
ance of new spots both in old and new localities. 
Dr. Headden has been studying our alkali soils and drainage 
waters for the past sixteen years, and he tells me that complaints of 
“brown spots on which nothing will grow” have been common, but 
more so during the past five years; reports have been received from 
the cantaloupe growers that their melons are deteriorating in quality 
without any assignable cause; truck gardens, alfalfa, oat, barley and 
sugar beet fields have been developing barren patches where a uni¬ 
form stand was always obtained in former years; in some parts of the 
state, the sugar content of the sugar beets as well as the purity and 
tonnage have fallen off until it is a ponderous question with the farm¬ 
ers and sugar factories whether the growing of sugar beets in those 
localities is any longer a profitable industry; but equally serious, if 
not even more so than any of these, is the destruction which is being 
wrought in some of the apple orchards of Colorado. Newly set trees, 
trees that have just come into bearing, and trees that are fifteen to 
twenty-five years old, in fact, trees of all ages, seem to suffer alike. 
It is not an isolated tree here and there that has died, but thousands, 
representing many acres of orchards in widely separated districts, have 
perished during the past two seasons. 
When one is brought face to face with facts of such tremendous 
economic importance as these, he can scarcely fail to be impressed 
vrith the deplorable condition of affairs, and is forced to the position 
that something out of the ordinary is taking place, and that it is not 
without a cause. 
With reference to the occurrence and distribution of the nitre 
areas, Dr. Headden gives the following in Bulletin 155 of this station: 
“This trouble was not confined to any one section, but was com¬ 
mon to several sections of the state. While it, in all probability, de¬ 
pends unon soil conditions, these conditions are met with in so many 
places that it is necessary to consider the condition rather than the soil 
