190 



Journal of Agricultural Research voi.xvi. no. 



Table VII. — Effect of strontiiivi carbonate on the growth of wheat — Fifth series 



"Not weighed. 



The results in the fifth series of experiments agree very closely with 

 those of the other experiments in which strontium carbonate was used, 

 both with respect to yields and the results obtained in the analyses of the 

 grain (Table VIII). They also show conclusively that the increased 

 yields obtained in the fourth series of experiments in which strontium 

 nitrate was used were due to the greater amounts of nitrate being present 

 which was assimilated and thus produced grains of wheat that contained 

 8 per cent more protein than was found in the control experiments, 

 which showed a protein content equivalent to that of wheat grown 

 under normal conditions. 



The last two experiments in the fifth scries show conclusively that 

 strontium wll not replace calcium in the growth of plants. They also 

 show, however, that strontium carbonate in the absence of calcium 

 carbonate fs apparently less toxic towards plants than barium carbon- 

 ate in the absence of calcium carbonate. It will be recalled that in the 

 first series of experiments, in which an attempt was made to grow cow- 

 peas in the presence of barium carbonate without calcium carbonate, 

 all the plants died soon after coming through the sand, whereas in 

 the case of the wheat plants in the presence of strontium carbonate and 

 the absence of calcium carbonate the plants did not die soon after they 



