1922] WOODARD—SOIL FERTILITY 93 
of hot ro per cent BaCl, solution added a drop at a time from a 
pipette. The solution was boiled for ten minutes, placed on the 
steam bath for two or three hours, and then removed and allowed 
to stand over night. The barium sulphate precipitate was then 
filtered off, washed with cold distilled water, transferred to a 
weighed porcelain crucible, ignited to a dull red in a muffle furnace, 
cooled in a desiccator, and weighed. Blanks were determined 
using the same reagents and adding the same quality of. the same 
sulphuric acid that was used in the determination. 
The loss on ignition was determined on samples which had 
been used for determining moisture. The moisture was deter- 
mined by heating 10 gm. of air dry soil in the oven for five or six 
hours. Part of the samples were heated to 100° C. in an ordinary 
oven and part of them to 35° C. ina vacuum oven. After weighing 
for the moisture determination, the sample was placed in the 
muffle furnace, heated to a dull red for an hour, cooled in a desic- 
cator, and weighed. The loss on ignition was calculated as percent- 
age of oven dry soil. Table I gives the results of the analytical 
work on all the soils analyzed. Phosphorus, sulphur, and volatile 
matter (loss on ignition) are reported as percentage of oven dry 
soil 
Sulphur is present in the soil either in the form of sulphates of 
calcium, magnesium, and iron, or in the form of organic matter. 
All the sulphates are quite soluble and are not readily adsorbed, 
so that they are leached out rapidly and only small amounts are 
present in the soil. On the other hand, the organic sulphur is 
insoluble and remains in the soil until oxidized to sulphates. One 
would expect, therefore, some sort of relation between the sulphur 
content of the soil and the volatile matter (loss on ignition), which 
is a rough method of determining the organic matter. The data 
in table I, however, indicate only a general relation, and that only 
when samples from the same soil type or closely related soil types 
are compared. The soil samples from Wisconsin are from the 
same soil type, but differ in amount of organic matter. There is 
also a difference in content of sulphur, and the higher sulphur con- 
tent is found in the sample with the higher content of organic mat- 
ter. This is true for both surface soil and subsoil. The Michigan 
