48 BOTANICAL GAZETTE [SEPTEMBER 
average fairly good, although here also the range is very great, 
and certain of the soils are deficient in this respect. 
The sulphur and phosphorus content of the Chicago soils is 
fairly good, while the organic matter content is high. As is 
brought out in connection with table VI, the samples are not 
typical for the cultivated soils of Chicago and its environs. They 
were taken in places where the organic matter had had a chance 
to accumulate. Their high sulphur content is to be accounted 
for mainly by their high organic matter content, the sulphur 
brought down by the rain accounting for little of the total sulphur. 
Although the Chicago samples should not be considered typical for 
cultivated soils, they are perhaps typical of soils of any section 
of the United States which have been in grass or any form of plant 
TABLE VII 
SUMMARY OF TABLES I, IT, IV, V, AND VI, GIVING AVERAGE OF SURFACE SOILS; SULPHUR 
AND PHOSPHORUS IN POUNDS PER”“ACRE, IGNITION VALUE IN PERCENTAGE 
Alabama Maryland Oklahoma |Central states} Chicago 
Samhats: § or ae 256 460 480 600 1220 
Phosphorus. 200. 7 go 580 694 1080 1400 
Ignition value.......... 2.194 4053 5.528 8.00 10.05 
Ratio ignition value to 
Moe. area te oe 182.5 196.9 230.0 263.3 263.1 
life for a number of years, or have been heavily manured. Such 
soils would be expected to be well supplied with organic matter, 
and to have a correspondingly high sulphur content. If conditions 
are right for active sulphofication, there should be an abundance of 
available sulphur. 7 
A further study has been made of this relation between the 
organic matter and total sulphur of the different groups of soils 
by determining the ratio of the organic matter to the total sulphur. 
As shown by table VII, this ratio is far from a constant. A 100 
per cent increase in the organic matter content does not mean a 
corresponding 100 per cent increase in the sulphur content. A 
comparison of the ratios for the different groups of soils, and of 
the figures for the sulphur content and the organic matter content 
seems to justify the statement, however, that there is a general 
