258 
Journal of Agricultural Research 
Vol. IX, No. 8 
obtained from decomposing green manures, whether derived from a non- 
leguminous or a leguminous crop, showed but slight differences in their 
solvent action upon the elements under examination. 
The total quantity of soil treated with the organic solvents would, in 
the case of the four materials studied, correspond approximately to a 
ratio of 2 parts of dry organic material to 100 parts of dry soil. The 
organic material was by no means completely decomposed at the time 
the last extraction was made. The amount of these elements dissolved 
from the soil as shown in Table IV was obtained during the 96 days the 
decomposition was in progress. We may therefore look upon the results 
in Table IV as representing roughly the gain in the soluble iron, calcium, 
magnesium, and phosphoric acid resulting from the addition of 2 per 
cent of organic matter to the soil, the amount dissolved from the soil 
by distillled water alone having been deducted. These figures show that 
the addition of organic matter to the soil markedly increased the amount 
of soluble iron, calcium, magnesium, and phosphoric acid. Expressed 
in pounds per acre-foot, the amounts range as follows: 
Iron.pounds.. 3 to 31 
Calcium.do 2,400 to 5,300 
Magnesium.do.... 640 to 1,300 
Phosphoric acid.do.... 670 to 1,400 
These figures do not necessarily represent an increased solubility of 
the soil components, however, except in the case of calcium and mag¬ 
nesium. The amount of iron or phosphoric acid recovered from the 
soil was in no instance equal to the amount added to the soil in the organic 
solvent. 
Separate solubility experiments were made by adding to the untreated 
soils the same amount of the elements under investigation as were added 
to the soils with the organic solvents. The salts, used individually, were 
the sulphates of iron, calcium, and magnesium, and dibasic sodium 
phosphate. Practically all the iron and about two-thirds of the mag¬ 
nesium and phosphoric acid added remained in the soil. On the other 
hand, the addition of calcium sulphate increased the solubility of cal¬ 
cium and magnesium, and the addition of magnesium sulphate increased 
the solubility of calcium. 
From the results obtained it was impossible to differentiate between 
the solvent action of the organic and inorganic compounds in the organic 
solvents. 
REACTION OF ORGANIC EXTRACTS TO INDICATORS 
The organic solvents obtained from the decomposing green manures 
used in making soil extracts were examined as to their reaction. None 
of the organic solvents obtained from the first extraction after 14 days' 
decomposition showed an alkaline reaction with phenolphthalein or an 
acid reaction with methyl orange, and only occasionally was a red color 
