ATMOSPHERIC-NITROGEN FERTILIZERS. 
25 
nitrate and urea were about as good, however. With regard to urea 
it will be noticed that there was a wide variation between the yields 
of series C and E in 1920. This again emphasizes the marked soil 
variations and shows the necessity of disregarding small differences 
in judging the value of any particular source of nitrogen. Series A, 
which received mixed salt, was likewise located on a very poor area 
with a shallow surface soil. Taking these points into consideration, 
there seemed to be little difference Detween the fertilizing values of 
urea, ammonium sulphate, sodium nitrate, and the two mixed salts. 
Calcium nitrate was not as satisfactory as the other materials, prob- 
ably because the nitrate-basic slag mixture became very hard after 
mixing and could not be distributed properly. The data are scarcely 
adequate for drawing sharp lines of distinction. The growth of cot- 
ton with urea is shown in Plate VII, Figure 1, and with the two 
mixed salts in Plate VIII, Figures 1 and 2. 
Table 13. — Yields per acre of corn from Section III of field No. 1 in 1920 and 1921, 
Plat. 
Yields of corn. 
1920 
1921 
Fertilizer ratio. 
Stalks 
(pounds). 
Grain (bushels). 
Stalks 
(pounds). 
Grain (bushels). 
Actual. 
Aver- 
age. 
In- 
crease 
over 
check. 
Actual. 
Aver- 
age. 
In- 
crease 
over 
check. 
Series A.— Mixed salt (from 
KC1): 
o-o-o 
16 
/ U 
\ 15 
12 
13 
14 
16 
I U 
\ 15 
12 
13 
14 
16 
/ U 
\ 15 
12 
13 
14 
16 
\ 15 
12 
13 
14 
16 
u 
12 
13 
14 
640 
1.200 
1,440 
2,160 
2,240 
2,720 
1,860 
2,700 
2,760 
3,520 
3,480 
3,720 
1,920 
2,640 
2,840 
3,280 
3,480 
3,800 
1,440 
2,100 
2,480 
2,360 
2,680 
3,200 
1,600 
2,220 
3,000 
3,040 
2,760 
3,480 
8.0 
7.7 
12.0 
8.0 
10.3 
20.0 
19.7 
18.0 
25.7 
17.7 
21.1 
38.3 
20.6 
12.0 
25.7 
14.9 
21.1 
38.3 
10.3 
12.0 
16.0 
5.7 
9.7 
26.3 
20.6 
24.0 
36.0 
22.9 
25.1 
38.9 
8.0 
\ 9.9 
8.0 
10.3 
20.0 
19.7 
\ 21.9 
17.7 
21.1 
38.3 
20.6 
} 18.9 
14.9 
21.1 
38.3 
10.3 
\ 14.0 
5.7 
9.7 
26.3 
20.6 
} 30.0 
22.9 
25.1 
38.9 
-1.9 
.4 
10.1 
-4.2 
-.8 
16.4 
-4.0 
2.2 
19.4 
-8.3 
-4.3 
12.3 
-7.1 
-4.9 
8.9 
1,760 
/ 1,560 
\ 1,920 
2,000 
2 200 
2,560 
2,160 
/ 1,920 
\ 2,200 
2,240 
2,360 
2,720 
2,120 
/ 1,800 
\ 2, 120 
2,040 
2,320 
2,640 
1,760 
/ 1,680 
\ 1,720 
1,680 
2,120 
2,480 
1,840 
f 1,680 
\ 2, 560 
2,320 
2,760 
2,920 
13.1 
4.6 
13.7 
10.3 
17.1 
30.9 
34.9 
13.1 
28.6 
21.1 
24.6 
37.7 
29.1 
6.3 
24.6 
14.9 
24.6 
41.1 
21.1 
8.0 
16.0 
9.1 
14.3 
32.0 
27.4 
21.7 
38.3 
31.4 
37.1 
45.1 
13.1 
} 9.2 
10.3 
17.1 
30.9 
34.9 
} 20.9 
21.1 
24.6 
37.7 
29.1 
} 15.5 
14.9 
24.6 
41.1 
21.1 
\ 12.0 
9.1 
14.3 
32.0 
27.4 
} 30.0 
31.4 
37.1 
45.1 
0-4-2 
1-4-2 
1 1 
2-1-2 
7.9 
21 7 
4-4-2 
Series B.— Sodium ni- 
trate: 1 
o-o-o 
0-4-2 
1-4-2 
2 
2-4-2 
3.7 
16.8 
4-4-2 
Series C— Urea: 
0-0-0 
0-4-2 
1-4-2 
-.6 
9.1 
25.6 
2-4-2 
4-4-2 
Series D . — Ammonium sul- 
phate: 
0-0-0 
0-4-2 
1-4-2 
-2.9 
2.3 
20.0 
2-4-2 
4-4-2 
Series E.— Urea: 2 
0-0-0 '.. 
0-4-2 
1-4-2 
1.4 
7.1 
15.1 
2-4-2 
4-4-2 
1 Mixed salt (from K 2 S0 4 ) was substituted for sodium nitrate in 1921. 
2 Calcium nitrate with basic slag was substituted for urea in 1921. 
