IRON AND ALUMINUM SALTS ON CLOVER SEEDLINGS. 125 



TOXIC effp:ct of iron and aluminum 



SALTS ON CLOVER SEEDLINGS. 



BY R. W. RUPRECHT. 



During the study of the soil from field A it was found that marked 

 amounts of soluble aluminum and iron salts were removed from the 

 plots receiving sulfate of ammonia by long-continued wasliing of the 

 soils with distilled water, while no aluminum and only traces of iron were 

 removed from the plots receiving nitrate of soda. This led to the con- 

 clusion that the iron and aluminum salts might be the causes of the poor 

 crops, and water-culture work, using these salts, was undertaken. 



At the time these culture experiments were started practically no work 

 of this nature, using iron and aluminum salts in water cultures, had been 

 reported. Since then, however, Connors of Indiana has pubhshed ^ results 

 of the toxic action of aluminum on corn seedlings, and Gile has published^ 

 results of the toxic effect of salts of iron on rice seedlings. 



The salts used by me were ferrous sulfate and aluminum ammonium 

 sulfate. The alum was used instead of aluminum sulfate because the 

 latter was not on hand. 



Standard solutions of the above salts of one-tenth molecular strength 

 were made up, and different amounts were added to the nutrient solution. 



The nutrient solution used was a slight modification of Pfeffers, and 

 was made up as follows: — 



Solution (a) : 20.5 grams MgSO^ dissolved in 350 c.c. distilled water. 

 Solution (6): 40 grams Ca(NOi;)-', 10 grams KNO.;, 20.56 grams NaaHPOi dis- 

 solved in 350 c.c. distilled water. 



One hundred cul)ic centimeters of solution (o) and 100 cubic centi- 

 meters of solution (6) were then added to 9.8 liters of distilled water, 

 and a few drops of ferric chloride solution added. 



The seeds were germinated on paraffin-coated wire gauze as described 

 in Bulletin No. 70, Bureau of Soils. When the stems of the seedlings 

 reached a length of 1 inch they were transferred to notched corks and 

 placed in the culture solutions. 



The culture solutions were contained in salt-mouth bottles of 250 

 cubic centimeters capacity, with necks having a diameter of 134 inches. 



1 Indiana Experiment Station Bui. No. 170. 



- Jour, of Agricultural Research, Vol. III., No. 3. 



