240 
Journal of Agricultural Research 
Vol. V, No. 6 
renewed unlimed soil with the usual complete-fertilizer treatment. Crop 
D was grown on soil which had borne two successive fertilized crops of 
rape and two successive crops of turnips (Brassica napus ), the last crop 
of turnips only receiving fertilizer. ,This clover crop was limed and 
fertilized. All the crops were allowed to reach the late-blooming stage, 
but they failed to produce seed. The roots of crops B and C were 
separated as carefully as possible from the soil and weighed separately 
from the tops. The yields of air-dried matter are given in Table II. 
Table II .—Average weights (in grants) of air-dried clover crops 
Hay. 
Treatment. 
Crop 
A. 
Crop Crop 
B. C. 
1. Control. 
2. Complete fertilizer. 
3. Complete fertilizer-fsodium sul¬ 
phate. 
4. Complete fertilizer+calcium sul¬ 
phate. 
5. Sodium sulphate only. 
6. Calcium sulphate only. 
7. Sulphur only... 
31.8 
45*3 
54-8 
46.0 
33-o 
27.8 
56. 2 
7i-5 
72. 2 
79. 2 
65-9 
62. 5 
49-1 
II. 7 
48.1 
67.0 
73-7 
23- 6 
29. o 
23. 6 
Crop 
D. 
92.0 
9S*o 
99.8 
108. 2 
93*9 
116.4 
Roots. 
Aver¬ 
age 
rela¬ 
tive 
yields 
of all 
crops. 
Crop 
A. 
Crop 
B. 
Crop 
C. 
100 
49*5 
16.8 
136 
48.5 
37*4 
153 
41*4 
3i*9 
160 
1 13 
123 
-38 
48.8 
67. 7 
92.9 
71.9 
36.4 
33* 1 
3i*9 
21.5 
Crop 
D. 
Aver¬ 
age 
rela¬ 
tive 
yields 
of 
crops 
B and 
C. 
100 
130 
in 
129 
152 
188 
141 
In the yield of hay there was no doubt about a marked stimulating 
effect of both sulphates upon growth. Stimulation was equally evident 
when they were added to the complete-fertilizer treatment and when they 
were applied alone. In both cases the best results were produced by the 
less soluble calcium sulphate. Elemental sulphur had a very depressing 
effect. The average yield from this treatment was but little more than 
one-third the yield from the control, and in crop D the clover entirely 
failed to grow where elemental sulphur was applied. Plate XX, figure 1, 
illustrates the influence of sulphates on the growth of clover. 
Root development from the complete-fertilizer treatment was depressed 
somewhat when sodium sulphate was also applied, but was unaffected 
when the calcium sulphate was added. We are inclined to ascribe this 
difference to the depressing effect of the more concentrated soil solution 
where the soluble sulphate was applied. The effect of the sulphates 
applied alone was very striking. In Plate XXI is shown the remarkable 
difference of root development from the different fertilizer treatments. 
From our limited amount of data calcium sulphate appears to be some¬ 
what more active than sodium sulphate in producing this effect. In 
any case it appears that in this soil a sulphate has specific effects on 
the root development of this species. This may properly explain the 
oftentimes beneficial effects observed in the application of land plaster 
