May 21,1917 Solubility of Certain Inorganic Soil Constituents 
257 
The various organic solvents are seen in Table III to exert a marked 
solvent action on the calcium and magnesium in soils. This action 
diminishes in intensity with the successive extracts, especially after 
the second. The mineral content of the organic solvents also decreases 
in the successive extracts, and these inorganic components doubtless 
play some part in the solubility of the soil minerals which can not be 
differentiated at this stage from the solvent action of the organic com¬ 
pounds. 
The total amount of the inorganic elements dissolved from each soil 
by the four extractions, as well as the total amount of the same elements 
added to the soils with the organic solvents, is given in Table IV. It 
will be seen that the total amount of phosphoric acid and of iron recov¬ 
ered from the soil extracts did not equal the amount present in the or¬ 
ganic solvents, and so added to the soil in making the extract of the 
latter. But the amount of these two elements dissolved from the soil 
was greatly in excess of the amount made soluble by water alone. In 
all cases the amount of calcium dissolved from the soil was much more 
than that added in the organic solvent, and in most cases also more 
magnesium was recovered than was added in the organic solvent. 
Table IV .—Total amounts of minerals removed from soils by the four successive organic 
extracts of freshly decomposing organic matter 
[Results expressed in parts per million of dry soils. Amounts removed by distilled water have been 
deducted] 
Organic sub¬ 
stance. 
Inorganic substances added 
to soil with the organic 
extracts. 
Clay-loam soil. 
Sandy-loam soil. 
Iron. 
Cal¬ 
cium. 
Mag¬ 
ne¬ 
sium. 
Phos¬ 
phoric 
acid. 
Iron. 
Cal¬ 
cium. 
Mag¬ 
ne¬ 
sium. 
Phos¬ 
phoric 
acid. 
Iron. 
Cal¬ 
cium. 
Mag¬ 
ne¬ 
sium. 
Phos¬ 
phoric 
acid. 
Barley. 
16. is 
232 
140 
238 
6.03 
1,176 
256 
168 
7 - 77 
1,206 
161 
206 
Sweet clover... 
46. 80 
419 
187 
374 
4-07 
325 
248 
7*44 
1,089 
234 
297 
Alfalfa. 
3- 80 
649 
230 
280 
• 77 
1.32 3 
202 
194 
2.14 
1,194 
169 
366 
Cow manure... 
3-18 
438 
204 
470 
1.86 
675 
205 
213 
1.86 
600 
207 
343 
It is evident from Table IV that the organic solvents obtained from 
the decomposing green manure were more effective in removing calcium 
than the organic solution obtained from the cow manure. Walters 1 has 
shown that acetic acid and proprionic add are formed in considerable 
quantities through the decomposition of green rye or green alfalfa, and 
the greater solvent action of the solutions of green manures is perhaps 
attributable in part to the presence of such acids. The amount of cal¬ 
cium or magnesium added to the soil with the organic solvents bears no 
relation to the amount of these elements recovered in the soil extracts. 
The amount of phosphoric acid recovered varies directly with the amount 
added to the soil in the organic solvent. The various organic solvents 
1 Walters, E. H. The presence ?.pd origin of volatile fatty adds in soils. (Abstract.) In Sdence, n. 
s. v. 44. no. na 8 , p. 217. 1916. 
