Nov. 8, 1915 Relation of Sulphur Compounds to Plant Nutrition 243 



point of special interest in these results is the fact that sodium sulphate 

 gave quite as good results as calcium sulphate when added to the com- 

 plete-fertilizer ration. This suggests that we were dealing here with a 

 plant more tolerant of the concentrated soil solution than were the legumes 

 grown. The radish was also more tolerant of elemental sulphur than 

 were any gf the legumes, although the growth in its presence was some- 

 what inferior to that of the control plants. 



Rape; (Brassica napus). — The variety grown was Dwarf Essex. Crop 

 A was grown on the usual soil, fresh and completely fertilized except for 

 elemental sulphur. Crop B followed crop A on the same soil. The soil 

 was refertilized and boxes with elemental-sulphur treatment were added. 

 Crop C was grown on fresh-fertilized soil. Crop D followed crop C on 

 the same soil and with the same fertilizer applications. The rape crops 

 were harvested when the death of the basal leaves indicated the near 

 approach of maturity. Data of the weights of the air-dried rape crops 

 are given in Table V. 



Table V. — Average weight (in grams) of air-dried rape crops 



Tops. 



Crop 

 A. 



Crop 



Crop 

 C. 



I Rela- 

 j tive 

 Crop I weights 

 D. I with 

 control 



Rela- 

 tive 



weights 

 with 



control 



Control 



Complete fertilizer 



Complete fertilizer-hsodium sul- 

 phate 



Complete fertilizer-f-calciura sul- 

 phate 



Sodium sulphate alone 



Calcium sulphate alone 



Sulphur alone 



29.0 

 30-9 



It is clearly evident that the addition of sulphates benefited this crop, 

 but especially so where they supplemented the complete-fertilizer ration. 

 Apparently the demands for sulphur of the higher yields of tops from 

 the fertilized plants accentuated the benefits from the sulphates in this 

 case (PI. XXII, fig. i). 



The sulphates of calcium and of sodium were equally efficient for 

 rape. In the case of the roots only the calcium sulphate gave beneficial 

 results. Possibly the soluble sodium sulphates increased the concentra- 

 tion of the soil solution to such an extent as to retard the growth of the 

 roots. It is well known that in water cultures the roots of plants are 

 more sensitive than the tops to such changes in the nutrient medium. 

 As in water cultures, so, too, in these soil cultures, it appears that the 

 growth of tops and of roots does not proceed parallel. 



