July 15,1925 Influence of Irrigation Water and Manure on Corn 
185 
tion treatments are given in Table II. In these results all grain 
grown without irrigation water and with the various manurial treat¬ 
ments is averaged together. Likewise, all the corn grown without 
manure and with varying irrigation treatments has been analyzed 
separately and then averaged in the table. Hence the results in all 
the tables represent the average analyses of the 12 years of corn and 
duplicate analyses from the grain grown on 12 different plats. There¬ 
fore the figures given should represent quite accurately the compo¬ 
sition of the grain grown with these different treatments during the 
past 12 years. 
Table II. — Percentages and pounds per acre of total nitrogen in the corn kernel 
grown with varying quantities of irrigation water and manure 
Treatment 
Nitrogen 
Nitrogen 
per acre 
Treatment 
Nitrogen 
Nitrogen 
per acre 
No irrigation water 1 . 
5 inches irrigation water 1 . 
10 inches irrigation water 1 _ 
20 inches irrigation water 1 ._„ 
30 inches irrigation water 1 _ 
Per cent 
2.07 
2.04 
2.02 
2.07 
1.99 
Pounds 
78.71 
91.34 
84.96 
98.17 
92.05 
40 incite? irrigation water 1 _ 
No manure 2 —.-. 
5 tons manure 2 .. 
15 tons manure 2 . 
Per cent 
2.03 
1.94 
2.07 
2.13 
Pounds 
90.81 
70.29 
95.09 
102.63 
1 And varying quantities of manure. 2 And varying quantities of irrigation water. 
In these results there appears to be little difference in the nitrogen 
content of the com kernel with varying quantities of irrigation water 
applied during the growing season. This is due to the manure, as 
an examination of the results from which the averages in the above 
table were obtained reveals the fact that the corn grown with no 
irrigation water contained 9 per cent more nitrogen than did that 
grown with 40 inches of water. The nitrogen content of the com 
increases progressively with the manure applied. Therefore the 
nitrogen content of grain depends on the quantity of available 
nitrogen in the soil. Although up to a certain point the speed with 
which nitrogen is made available is dependent upon the moisture 
content of the soil (4), the quantity which remains within the feeding 
area of the plant rather rapidly decreases as the water applied in 
creases, because of its great solubility (3 ). Therefore the high protein 
content of dry-farm grains is due to two factors: (1) The storage 
of two years’ nitrogen in the surface soil due to summer-fallowing 
(3 ); (2) the scant rainfall permitting the nitrates formed to remain 
and through upward capillarity to be concentrated in the surface-foot 
sections. Hence the nutrient media on which the plant is feeding 
is high in nitrates and the plant consequently builds protoplasm 
having a high nitrogen concentration. 
Slightly larger quantities of total nitrogen are removed in the com 
kernel from the irrigated soil than from the nonirrigated. However, 
there is no uniformity in the results in this respect. The grain 
f rown on the manured soil, on the other hand, shows a relationship 
etween the nitrogen applied and that removed in the crop. Thirty- 
one per cent of the added nitrogen was accounted for in the corn 
kernel grown on the soil receiving 5 tons of manure yearly, and only 
14 per cent where 15 tons to the acre were applied; but the excess 
applied in the 15-ton application accumulates (6) in the soil, and 
if the soil is not manured for a number of years it yields much of this 
remaining nitrogen to the grain grown later. 
