ATMOSPHERIC-NITROGEN FERTILIZERS. 29 
The yields are given in Table 14. Ammonium nitrate produced 
good increases and was an entirely satisfactory nitrogen carrier for 
cotton. The yields with the various rates of application of urea and 
ammonium sulphate were unsatisfactory because of the soil, as pre- 
viously pointed out. The two materials affected growth and matu- 
rity in the same manner. The yields with urea were slightly better 
than with ammonium sulphate, but the differences are not significant. 
The yields with cyanamid or cyanamid and calcium nitrate were 
considerably below those on the other three series, due largely to the 
poorer soil. In addition, the retarding effect of cvanamid did 
directly lower the yields and increased the boll-weevil injury. The 
failure of calcium nitrate to improve the mixture is contrary to 
results reported in the literature. 
Results with corn. — Because of dry weather a decided injury was 
noted on all of the corn plats receiving 80 pounds of the ammonia 
equivalent, regardless of source. Cyanamid was more injurious than 
the other materials, but no more so than the same (quantities of 
nitrogen supplied in a calcium-nitrate-cyan amid mixture. The 
materials were all equally available so far as observations could de- 
termine. Table 14 gives the results. 
A consideration of the yields on the check plats of this entire 
section of the field emphasizes the marked irregularities of the soil. 
Variations of 100 per cent or more are not uncommon between 
check plats of the same series or between corresponding check plats 
of two different series joined end to end. Small differences between 
treatments are therefore unimportant. 
The ammonium-nitrate series of plats was located on the most 
productive and wettest portion of the field. Consequently, the 
yields on all plats were good, regardless of fertilizer treatment. The 
increases produced by ammonium nitrate were slight, and the data 
do not permit any conclusions other than to say that the material 
gave responses similar to urea and ammonium sulphate. 
The value of the yields with urea are likewise minimized by irregu- 
lar soil conditions, but since the fertility was much lower than on the 
ammomum-nitrate series the increases produced by the urea were 
much more marked. Taking into consideration the check plats, 
urea seems equally as good as ammonium sulphate. 
Cyanamid, either alone or with calcium nitrate, gave very good 
increases in yields except where the soil was already so rich that the 
fertilizer was ineffective. Neither the observations during growth 
nor the final yields showed cyanamid to be inferior to the other 
nitrogen carriers. The mixture with calcium nitrate gave larger 
increases in yields in some cases than cyanamid alone, but the soil 
was somewhat poorer. 
AMMONIUM CHLORID AND THE MIXED SALTS. — SECTION II. 
Results with cotton. — The relative values of the two mixed salts 
and ammonium chlorid, as shown by the figures in Table 15, are 
practically the same. The largest increases in yields were produced 
by the chlorid mixed salt, ammonium chlorid being second and the 
sulphate mixed salt third. It will be noted, however, that the chlorid 
mixed salt was used on the poorest soil. The actual yields were 
usually smaller with this material than with the others, but since the 
check plats were low the increases were comparatively larger. The 
