188 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
MAGNESIUM 
The average magnesium content of the same corn is given in Table VI. 
Table VI .—Percentages and pounds per acre of total magnesium in the corn 
kernel grown with varying quantities of irrigation water and manure 
Treatment 
Mag¬ 
nesium 
Mag¬ 
nesium 
per acre 
Treatment 
Mag¬ 
nesium 
Mag¬ 
nesium 
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 
0.20 
.20 
.20 
.20 
.21 
Pounds 
7.57 
9.59 
7.98 
9.65 
9.12 
40 inches irrigation water 1 _ 
No manure 2 . 
5 tons manure 2 __ 
15 tons manure 2 . 
Per cent 
0.20 
.19 
.22 
.21 
Pounds 
8.92 
6.72 
10.11 
9.58 
l And varying quantities of manure. 2 And varying quantities of irrigation water. 
The magnesium content of the corn is nearly constant with all 
water treatments. The magnesium content of thi& corn is nearly 
twice that reported by von Wolff (8 } p. 603). Even with the high 
magnesium content of this grain grown on unmanured soil, manured 
gram shows a gain in magnesium content of 15 per cent. 
The calcium-magnesium ratio of corn is 1:1.37. The total quan¬ 
tity of calcium ana magnesium removed from the soil increases with 
the irrigation water and manure applied. The results all tend to 
bear out the theory that the change m the composition of the grain 
is due primarily to an increased available supply of plant food result¬ 
ing from increased bacterial activity. This m turn is a function of 
the moisture and organic content of the soil {2, 4)- 
POTASSIUM 
The potassium content of the corn kernel is given in Table VII. 
Table VII .—Percentages and pounds per acre of total potassium in the corn 
kernel grown with varying quantities of irrigation water and manure treatment 
Treatment 
Potas¬ 
sium 
Potas¬ 
sium 
per acre 
Treatment 
Potas¬ 
sium 
Potas¬ 
sium 
per acre 
No irrigation water 1 . 
5 inches irrigation water 1 . 
10 inches irrigation water 2 _ 
20 inches irrigation water 1 - 
30 inches irrigation water 1 ...- 
Per cent 
0.37 
.39 
.40 
.40 
.40 
Pounds 
14.62 
16.42 
16.60 
19.38 
17.78 
40 inches irrigation water K... 
No manure 2 . 
5 tons manure 2 . 
15 tons manure 2 _. 
Per cent 
0.41 
.38 
.39 
.41 
Pound 
18.09 
13.46 
18.27 
19.72 
i And varying quantities of manure. 2 And varying quantities of irrigation water. 
The potassium content of the corn kernel increases with increase 
of the water applied during the growing season. Corn grown with 
40 inches of irrigation water contains 12 per cent more potassium 
than that grown without irrigation water; that grown with 15 tons 
of manure contains 8 per cent more potassium than that grown 
without manure. 
