1922] WOODARD—SOIL FERTILITY 105 
3. The sulphur contents in the surface soil vary from 0.0118 to 
0.0905 per cent, while the phosphorus contents vary from 0.0360 
to 0.3407 per cent. All the upland soils and most of the alluvial 
soils are low in sulphur. . Most of the Kentucky soils and one of 
the Indiana soils are high in phosphorus. This is undoubtedly due 
to the influence of the rock from which the soils were formed, as all 
the Kentucky samples were from soils derived either from the Tren- 
ton limestone or the Cincinnati limestone, both of which are high 
in phosphorus content. 
4. The sulphur and phosphorus contents were calculated to 
pounds per acre in the surface soil, and compared with the amounts 
of sulphur and phosphorus removed by maximum crops of corn, 
wheat, timothy, clover, and alfalfa. The highest sulphur content 
is sufficient for only 39 years of alfalfa, 139 of clover, 159 of timothy, 
355 Of wheat, or 232 of corn; while the lowest sulphur content is 
sufficient for only 5 years of alfalfa,'18 of clover, 21 of timothy, 46 
of wheat, or 30 of corn. The lowest phosphorus content is equal 
to the amount removed by 42 years of corn, 60 of wheat, 80 of 
timothy, 36 of clover, or 20 of alfalfa. On the other hand, it would 
take 4o1 years of corn, 568 of wheat, 757 of timothy, 341 of clover, 
or 189 of alfalfa to remove as much phosphorus as is found in the 
soil with the highest phosphorus content. 
5. On some of the soils tobacco, clover, and alfalfa have been 
benefited by the use of gypsum. The results, however, are not 
quantitative. More field experiments are needed and greater care 
should be taken to eliminate other factors as far as possible. Each 
treatment should be replicated to reduce the probable error. 
This investigation was conducted under a research fellowship 
from the Gypsum Industries Association. The work was performed 
at the University of Chicago in the Hull Botanical Laboratory under 
the direction of Dr. Witt1am Crocker. The author wishes to 
thank the Gypsum Industries Association for their kindness in 
furnishing the fellowship and Dr. Crocker for his kind and helpful 
advice and criticism. Thanks are also due Dr. FREDERICK Kocu 
for his kind advice and criticism of analytical methods. 
University or ILLINOIS 
Ay ALi, 
