ATMOSPHERIC-NITROGEN FERTILIZERS. 
27 
certain areas. However, it was only where cyanamid was used that 
enough plants were killed to affect the stand appreciably. At the 
rate of 40 pounds per acre of ammonia, as cyanamid, the injuries were 
temporary, but with 80 pounds about half of the plants were killed, 
as is shown in Plate IV, Figure 2. Where calcium nitrate was used 
with cyanamid the extent of injury depended almost wholly upon 
the amouDt of cyanamid used. 
— t30'- — — *j*>'|« - SO ' ~— j l> 1 » 30 A /O' U 90'— -A ' 
^4tt 
ZAm.Cl. 
I — 
Fig. 2.— Diagram of field No. 2 lo- 
cated at Muscle Shoals, Ala., show- 
ing plat arrangements and treat- 
ments for the season of 1921. The 
soil type is Colbert silt loam. Three 
rows per plat without buffer row. 
Size of plats one-fortieth of an acre. 
The index figures refer to the num- 
ber of pounds of NH3, P2O5, and 
K2O used per acre. Ac. P. = Acid 
phosphate; B. Slag ■= basic slag; 
K == potassium sulphate; Am. S. 
= ammonium sulphate; Am. N. = 
ammonium nitrate; Ca. N. = cal- 
cium nitrate; Cyan. = cyanamid; 
Am. CI. = ammonium chlorid; M. 
S. (CI.) = mixed salt made from 
potassium chlorid and ammonium 
nitrate; M. S. (S0 4 )= mixed salt 
made from potassium sulphate and 
ammonium nitrate. 
The soil variations were a greater factor in determining yields 
than the fertilizer treatments. On the ammonium-nitrate series 
the soil was the most uniform and best adapted to cotton of any. 
On the other hand, the soil of series B and C was too heavy and com- 
pact for cotton and too fertile to give satisfactory results in a fertilizer 
experiment. On these two series early growth was slow, while the 
late growth was unusually rapid. The result was a heavy stalk 
production, poor fruiting, and maximum boll-weevil injury, especially 
with the largest applications of nitrogen. The soil of series D and E 
was exceedingly variable, one side being very productive and the 
other the poorest in the field, 
