Nov. 8. 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 (Pistim sativum). — The variety grown was Little 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. — Ai'crage iveights {in grams) of the air-dried pea crop 



Straw and 

 pods. 



Relative 

 yields of 

 seeds. 



Relative 

 yields of 

 straw. 



1. Gintrol 



2. Complete fertilizer 



3. Complete fertilizer +sodium sulphate . 



4. Complete fertilizer+calcium sulphate 



5. Sodium sulphate only 



6. Calcium sulphate only 



7 . Sulphur only 



o. 18 

 . 21 

 •24 

 •97 

 .60 

 .82 

 ■03 



4.42 



3-99 

 4. 12 

 4-54 

 4.41 

 3-84 

 2.47 



100 

 117 

 133 

 539 



456 



100 

 90 

 93 

 103 

 100 



87 

 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 



