Nov. s, 191s Relation of Sulphur Compounds to Plant Nutrition 
241 
to clover. While the form of the root system developed under the 
two treatments may not involve a larger feeding surface in the one case 
as compared with the other, yet it does seem very probable that the long 
root system developed where sulphate concentration was larger would 
favor that plant in times of limited water supply. The unavoidable 
conclusion from the results with red clover is that the reenforcement of 
the limited soil supplies of sulphur compounds by sulphates of sodium and 
calcium was decidedly beneficial to this crop. 
Peas (Pisum sativum ).—The variety grown was Tittle Gem, a dwarf 
variety. Strong seedlings were transplanted to the soil six days after 
they were placed on the germinator. The soils had already produced 
two crops of clover and three of beans, the first crop of clover and the 
first and last crops of beans having been fertilized. Both clover crops 
had been limed. No elemental sulphur was added to box 13 and 14 for 
the first crops of beans. The data of the pea crop are given in Table III. 
Table) III .—Average weights (in grams) of the air-dried pea crop 
Treatment. 
Seed. 
Straw and 
pods. 
Relative 
yields of 
seeds. 
Relative 
yields of 
straw. 
I. 
Control. 
0. 18 
4.42 
IOO 
IOO 
2. 
Complete fertilizer. 
. 21 
3 - 99 
117 
90 
3 * 
Complete fertilizer+sodium sulphate.... 
. 24 
4. 12 
133 
93 
4 - 
Complete fertilizer-j-calcium sulphate .... 
•97 
4-54 
539 
103 
5 - 
Sodium sulphate only. 
. 60 
4.41 
333 
IOO 
6. 
Calcium sulphate only. 
.82 
3* 84 
456 
87 
7 - 
Sulphur only. 
•03 
2. 47 
17 
56 
This crop did not grow vigorously, and the differences of yields have, 
therefore, less significance than with the preceding crops. However, the 
increased yields of seeds where sulphates were added is surely remark¬ 
able. This is especially true for the calcium sulphate, both when added 
to the complete fertilizer and when added alone. Both sulphates when 
applied alone gave remarkable increases over the control soils. Sulphur 
alone was much more toxic than was the case with the crops already 
described. The straw shows no very great differences of yields, except 
where sulphur alone was applied. Here the depressing effect was some¬ 
what less than in the case of the other leguminous crops. 
Probably the negative effect of fertilizers upon the growth of straw 
on this crop should be attributed to the fact that the soils had been ex¬ 
cessively cropped and fertilized. This would tend, on the one hand, to 
exhaust the control soil and, on the other hand, to render the fertilized 
soils too concentrated in soluble salts for good growth. Hence, the 
development was even poorer in some cases than the control. Appar¬ 
ently the sulphates especially favored the development of seed in this 
weakened crop. That such was not the case where sodium sulphate 
