lOO Journal of Agricultural Research voi. xvii. No. 3 



2. To eliminate the sulphur compounds acting upon the insoluble 

 plant food and soil organisms, these plants were also grown on sand 

 receiving the sterilized soil extract and certain pots received the addi- 

 tional sulphur fertilizers as the soil. 



3. Sodium sulphate and calcium sulphate were added daily in solu- 

 tion form. The elemental sulphur was mixed with the soil and calcium 

 carbonate at the time of sowing the seed. 



4. Sodium nitrate solution was added daily to eliminate available 

 nitrogen as a limiting factor of growth and also to determine what effect 

 sulphates would have on nitrogen assimilation by the plant. 



5. The plants were grown for two and one-half months and the dry 

 weights of the tops were recorded. The total sulphur and nitrogen was 

 determined in the majority of cases. 



CONCLUSIONvS 



1. Addition of sulphate and elemental sulphur enhanced the growth 

 of the plants grown in pots in the greenhouse. 



2. The corresponding increases obtained on the soil extracts indi- 

 cated that sulphur acted directly in promoting this growth. 



3. The great increase in the nitrogen content of the clover grown on 

 the soil where sulphates had been added is the result in all probability 

 of the sulphates stimulating the action of the legume bacteria. 



4. Sulphates caused increased root development and number of 

 nodules on the clover grown in the soil pots. 



LITERATURE CITED 

 (i) Ames, J. W., AND BoLTz, G. E. 



1916. SULPHUR IN RELATION TO SOILS AND CROPS. Ohio Agr. Exp. Bul. 292, 



p. 219-256. References, p. 255-256. 



(2) and Richmond, T. E. 



1918. SLTLFOFICATION IN RELATION TO NITROGEN TRANSFORMATIONS. In Soil 



Sci., V. 5, no. 4, p. 311-321. 



(3) Bernhard, a. D. 



1910. EXPERIMENTS ON CONTROL OF" POTATO SCAB. (Abstract.) In Chem. 

 Abstracts, v. 5, no. 13, p. 2295. 1911. Original article (Versuche zur 

 Bekampfung dcs Kartoffelschorfes) in Deut. Landw. Presse, Jahrg. 37, 

 No. 18, p. 204-205. 1910. Not seen. 



(4) BOULLANGER, E., and DUGARDIN, M. 



1912. M^CANISME DE l'action FERTIlisante du souFrE. In Compt. Rend., 

 Acad. Sci. [Paris], t. 155, no. 4, p. 327-329. 



(5) Brown, P. E-, and Gwinn, A. R. 



1917. EFFECT OF SULFUR AND MANURE ON AVAILABILITY OP ROCK PHOSPHATE 



IN SOIL. la. Agr. Exp. Sta. Research Bul. 43, p. 367-389. Bibliogra- 

 phy, p. 389. 



(6) and Kellogg, E. H. 



1914. SULFOFICATION IN SOILS. la. Agr. Exp. Sta. Research Bul. 18, p. 49-111. 



(7) 



191 5. SULFUR AND PERMANENT SOIL FERTILITY IN lOWA. In Jour. Amer. 



Soc. Agron., v. 7, no. 3, p. 97-108. 



