776 
Journal of Agricultural Research 
Vol. V, No. 16 
others. At the end of six weeks the plants were removed and the roots 
measured. There was a distinct difference in root development, as shown 
in Table VII. Plate LVI, figure i, shows very plainly the decided 
differences in root development. The results indicate that the increase 
in root development is as great with only o.oi per cent of calcium sul¬ 
phate added as with larger amounts. The test tubes treated with 
calcium sulphate were chosen at random from the calcium-sulphate 
series. They appear lighter because of the suspension of small particles 
of the salt in the agar. 
The results of this experiment show that calcium sulphate greatly 
increases root development. However, in concentrations as high as o.i 
per cent, growth is slightly retarded. The increase in root development 
may be of considerable importance, first, because it enables the plant to 
reach out over a greater area for nourishment, and second, because of 
the greater field, the plant will be able to withstand drought better and 
thrive on poorer soil. The increase in root development may be the cause 
of the increase in the yield of clover when calcium sulphate is added 
to the soil. This is in confirmation of the work of Hart and Tottingham. 1 
These results are given in Table VII, which represents the average of 
io test tubes for each concentration used. 
Table VII .—Effect of calcium sulphate on the growth of red glover 
Treatment. 
Length of 
root. 
Length of 
stem. 
Untreated. 
Cm. 
V 8 
Cm. 
4. 2 
4. 19 
4 - 7 
4. 6 
Given 0.01 per cent of calcium sulphate. 
O' 
e. I 
. 02 per cent of calcium sulphate. 
5-5 
5. 01 
4 * 93 
. 05 per cent of calcium sulphate. 
. 10 per cent of calcium sulphate. 
* v 
O 0 
t 
EFFECT OF SULPHUR AND CALCIUM SULPHATE UPON CLOVER GROWN 
IN VARIOUS TYPES OF SOILS 
The effect of calcium sulphate upon clover grown on Miami silt-loam 
soil was tested. For this experiment ten i-gallon jars were used. Four 
kgm. of Miami silt-loam soil and various amounts of calcium sulphate 
were added to each. The jars were kept in the greenhouse and the 
moisture content held at 18 per cent. Each jar was seeded with red 
clover and then inoculated with a pure culture of red-clover organisms. 
After two weeks the jars were thinned to io plants. 
During the first few weeks there was no apparent difference in the size 
of the plants. At the end of seven weeks an increase in growth in jars 
3 to 8, inclusive, was noted. In jars 9 and 10, to which 0.1 per cent of 
calcium sulphate had been added, there was a decrease in growth. Four 
1 Hart, E. B., and Tottingham, W. E. Op. dt. 
