Feb. 26,1917 
Effect of Water and Manure on Nitrates in Soils 
35i 
crease began. The average for all manures on fallow land shows that 
the nitrates began to decrease in amount when the irrigation was 10 
inches. The first 5 inches of water applied resulted in more nitrates 
for the first 3 feet than where no water was applied. The differences in 
favor of the smaller irrigations appear more in the upper feet than in 
the lower in most cases. 
It may be seen that although the nitrate content of the fallow soils 
is more than double that of the cropped for no manuring and more than 
three times for the respective treatments when manure was added, the 
general relationship between the cropped and fallow plots for nitrates 
is somewhat similar for the different manuring treatments. This is 
found both for the water applied and the depth, although the fallow plots 
are inclined to be more irregular than the cropped ones. The difference 
between cropped and fallow soils is less pronounced with the larger 
irrigations than with none or the smaller ones. The proportionate 
increase in nitrates for increasing amounts of manure is greater for the 
fallow than for the cropped soils. Fallow and cropped plots differ in 
nitrate content, on the average, about the same at each foot in depth. 
Tables V and VI summarize the effect on soil nitrates of manure and 
moisture if considered separately. 
Tabl3 V .—Effect of manure on the nitrates in cropped and fallow soil. Average of all 
moisture treatments for three years 
[Results expressed as p. p. m. of sodium nitrate] 
Total nitrates. 
Depth of soil. 
No manure. 
5 tons of manure. 
15 tons of manure. 
Average. 
Cropped. 
Fallow, 
Cropped. 
Fallow. 
Cropped. 
Fallow. 
Cropped. 
Fallow. 
Feet . 
14*7 
27.8 
13-2 
41.2 
21.8 
56.8 
16.6 
41.9 
13-0 
20.6 
7-4 
35-4 
14.4 
49-9 
11.6 
35-3 
8.8 
22.8 
7.4 
37-2 
12. 5 
38.3 
9.6 
32.8 
12.1 
26.3 
7-6 
34-6 
12.9 
37-4 
10.9 
32.8 
10.3 
26. 7 
6.8 
32.8 
12.3 
35-9 
9-8 
31.8 
6. 
10.9 
28.3 
8.5 
35-9 
9.0 
44.1 
9-5 
36.1 
7 . 
11.6 
22.3 
7.8 
33-2 
12.0 
43-4 
10. s 
33-0 
8. 
11. 5 
21.6 
9.6 
26.2 
10.6 
38.6 
10.6 
28.8 
9 . 
10.1 
18.3 
8-5 
23-9 
11.2 
34-6 
9.9 
25.6 
10. 
8.6 
19*6 
9.2 
28.3 
11.0 
39-9 
9.6 
29-3 
Average. 
11.2 
23-4 | 
8.6 
32.9 
12.8 
41.9 j 
10.9 
32.7 
