ATMOSPHERIOXITROGEX FERTILIZERS. 9 
maturity slightly while the largest amounts produced a slight re- 
tardation, as is usually the case with other readily available sources 
of nitrogen. 
Ammonium nitrate where used on winter crops gave exactly the 
same effects as sodium nitrate, and it was impossible to detect any 
difference between the two treatments at any time during the grow- 
ing season. 
AMMONIUM PHOSPHATE AND AMMONIATED SUPERPHOSPHATE. 
The early-growth effects in the experiments with ammonium phos- 
phate and ammoniated superphosphate were excellent, both the 
cotton and corn usually being as large as or larger than any in the 
field during the first six weeks of growth. The materials were as 
available as ammonium sulphate and showed no bad effects except 
in cases of extreme drought, where large applications of all soluble 
salts injured the plants. The materials were unquestionably good 
nitrogen carriers. 
The growth during the latter half of the season was likewise good, 
but owing to the abnormally large quantities of phosphorus supplied 
the increases over the check plats tended to become less and less pro- 
nounced as the season advanced. Even though the primary purpose 
of these experiments was to determine the availability of the nitrogen 
it was impossible at the same time to avoid adding an abnormally 
large quantity of available phosphorus. The soils on the experimen- 
tal areas were rather deficient in this element, and hence its stimu- 
lating effect largely obliterated the responses produced by the 
nitrogen. 
AMMONIUM CHLORID. 
Germination was slightly injured by the largest rates of application 
in a few instances, the effects being a little more pronounced than 
with equivalent applications of sodium nitrate or ammonium sulphate 
used under similar conditions. During the two weeks subsequent to 
germination there occurred a distinct burning in some instances, 
particularly with corn receiving 40 pounds of ammonia per acre. 
During the season of 1920 this injury was sufficient to kill about 10 
per cent of the corn plants. 
The later growth corresponded to that on near-by ammonium 
sulphate plats except where the most severe burning took place. In 
these cases the plants never seemed to overcome entirely the early 
retardation. With the smaller applications, where no burning oc- 
curred, the corn and cotton seemed to make even better growth than 
with ammonium sulphate. These facts suggested a possible injury 
in the presence of a large concentration of the chlorid ion and a stim- 
ulation with smaller quantities. Any bad effects noted were much 
more pronounced in 1920 than in 1921, even though used on the 
same soil both years. The latter year ammonium chlorid produced 
effects more nearly corresponding to those noted with ammonium 
sulphate. 
UREA. 
The observations during growth showed no difference at any time 
between the urea plats and those receiving either of the two standard 
materials. Urea produced no germination injuries, was immediately 
