ATMOSPHERIC-XITROGEX FERTILIZERS. 
31 
rious portions of the plat. It was well suited to corn but too 
.impact for the best results with cotton. The nitrogenous fertilizers 
i ; sed were ammonium sulphate, ammonium chlorid, double salt, 
ammoniated superphosphate, ammonium phosphate, and cyanamid. 
The plat arrangements are shown in Figure 3. 
Results with cotton. — The yields of seed cotton for the two successive 
seasons are shown in Table 16. These show a decrease of about 
i0 to 30 per cent on the average for 1921 as compared with 1920, 
due to the dry weather and the boll weevil. The latter injury was 
rather uniformly distributed over the field and for the most part 
limited to the late crop. Consequently, the injury was greatest on 
those plats where the cotton was slowest in reaching maturity. These 
were the unfertilized areas and the plats receiving the largest applica- 
tions of nitrogen, especially cyanamid. 
COZN. 
SECT/ON H. SECTION I. 
.14?: 
COTTON. 
SECT/ON E. SECTION I. 
Fig. 3.— Diagram of field No. 3 located at Muscle Shoa 
for the season of 1921. The soil type is Colbert silt 
s, Ala., showing plat arrangements and treatments 
oam. Three rows per plat with buffer row. Size 
of plats, one twenty-fifth of an acre. The index figures refer to the number of pounds of NH 3 , P 2 5 , and 
K 2 used per acre. Ac. P. = Acid phosphate; K = potassium sulphate; Cyan. = cyanamid; Am. S. = 
ammonium sulphate; Am. CI. = ammonium chlorid; D. S. = double salts; Am. Sup. = ammoniated 
superphosphate; Am. P. = ammonium phosphate; B. Slag = basic slag. 
The increases in seed cotton produced by ammonium sulphate and 
double salt were of about the same magnitude, the yields with both 
materials increasing as the food supplied increased. On the other 
hand, ammonium chlorid showed opposite results for both seasons, 
the largest yield being obtained with the smallest nitrogen treatment. 
These plats were located on soil that seemed to be quite uniform. 
This would indicate that under the conditions of this test the chlorid 
ion was toxic when used in large concentrations and stimulating at 
the smaller rates. The responses of cotton to double salt and 
ammonium chlorid are shown in Plate X, Figure 1, and Plate XI, 
Figure 1, respectively. 
The ammonium phosphate and ammoniated superphosphate plats 
of Section II were located on soil that was too rich in nitrogen to give 
large responses to additions of this element. Phosphorus was some- 
what deficient, however, and its use largely blotted out the effects 
of the nitrogen. The effects of ammonium phosphate and ammo- 
niated superphosphate on growth corresponded to those noted with 
