1922] EATON—SULPHUR CONTENT OF SOILS 4G 
correlation between the two, that a soil with a large amount of 
organic matter also contains a large amount of sulphur. That 
the correlation is not closer may be accounted for, at least in part, 
by the fact that plants differ greatly in their sulphur content. 
The source of the organic matter present in the soil has a great deal 
to do with the amount of sulphur the soil contains. This fact 
may account, at least partly, for the cases (shown by the tables 
giving the detailed data of the soil analyses) in which there does 
not seem to be any correlation at all between the organic matter 
and sulphur content. A high organic matter content may be 
correlated with a low sulphur content, but these cases should be 
considered exceptions to the general rule that a soil containing a 
large amount of organic matter also contains a large amount of 
sulphur, a rule which is seen more clearly when the sulphur and 
organic matter content of a number of soils are averaged. In 
general, the sulphur content of soils is greater than that of the 
corresponding subsoils. 
Table VIII gives the number of crops that could be grown from 
the amount of sulphur present in the various groups of soils as 
summarized in table VII. Brown and Ketioce’s (2) figures 
for the amount of sulphur removed by maximum yields of these 
crops have been used. They assume that the entire crop is removed 
from the soil. In the Maryland and central states soils, which 
include the most important agricultural soils, the number of crops 
supply of sulphur in the poorest soil and in the best soil is given in 
the column “Range.” Table VIII shows that there is enough 
sulphur present in most of the soils for comparatively few maximum 
crops of such high sulphur-containing plants as alfalfa and potatoes. 
The other crops contain less sulphur, and therefore a greater 
number of maximum crops of these could be grown. 
Most of the sulphur of the different soils is in the organic form 
and unavailable for the plant, and it is not known how rapidly 
sulphofication is making it available. When the sulphur content 
of a soil is as low as it is in the Alabama, Maryland, Oklahoma, 
and several of the central states soils, however, sulphofication may 
hot produce enough available sulphur to secure maximum yields of 
most crops. Considered from this standpoint, table VIII may 
