264 
Journal of Agricultural Research 
Vol. IX, No. 8 
Table X .—Solubility of soil minerals as effected by the addition of organic manures , lime, 
gypsum, and sodium carbonate six months after the addition of substances to the soil 
[Results expressed as parts per million of dry soil] 
Soil treatment. 
Iron. 
Calcium. 
Magnesium. 
Phosphoric 
acid. 
Control (nothing added). 
O- 75 
25 
7 
16 
3 per cent horse manure only. 
•39 
42 
7 
38 
3 per cent horse manure plus 3 per cent cal¬ 
cium carbonate. 
•30 
46 
8 
32 
3 per cent horse manure plus 0.2 per cent 
sodium carbonate. 
• 5 1 
33 
9 
38 
3 per cent horse manure plus 3 per cent cal¬ 
cium sulphate... 
Trace. 
1,070 
81 
25 
Control (nothing added). 
' • 
23 
5 
17 
3 per cent alfalfa only. 
• 39 
53 
12 
25 
3 per cent alfalfa plus 3 per cent calcium 
carbonate... 
. 60 
48 
7 
33 
3 per cent alfalfa plus 0.2 per cent sodium 
carbonate. 
. 69 
39 
7 
30 
3 per cent alfalfa plus 3 per cent calcium 
sulphate. : . 
3.00 
925 
63 
18 
Table XI .—Solubility of iron and calcium in soils as effected by the addition of organic 
substances three months after the addition of substances to the soil 
[Results expressed as parts per million of dry soil] 
Soil treatment. 
Soil No. 1. 
Soil No. 2. 
Iron. 
Calcium. 
Iron. 
Calcium. 
Control (nothing added). 
0. 50 
44 
0. 80 
21 
Cow manure, 0.2 per cent. 
•65 
49 
. 80 
15 
Cow manure, 1 per cent. 
.90 
53 
.90 
34 
Cow manure, 3 per cent. 
Sweet-clover hay, 1 per cent.. 
2. 50 
58 
I- 57 
4 i 
•65 
29 
• 77 
21 
Sweet-clover hay, 3 per cent. 
• 77 
40 
i- 53 
35 
In another experiment two types of soil from two orange groves near 
Riverside, Cal., were treated with different kinds of organic matter in 
different amounts, with and without the addition of certain inorganic 
substances. These soils were put into nonsoluble containers, placed in 
a greenhouse in Washington, D. C., kept moist, and stirred occasionally 
for a period of about 6 months. The soils were then sampled and the 
specific electrical conductivities determined. The results are shown in 
Tables XII and XIII. The specific-conductivity figures have all been 
multiplied by io 5 . 
The presence of organic matter considerably increased the amount of 
electrolytes in both soils. Three per cent of organic matter increased the 
conductivity more than did 1 per cent, and alfalfa produced a greater 
