RESULTS OF EXPERIMENTS, 31 



prop(n^tionato to their smaller resistance to this salt as shown in 

 these water cultures. This can not definitely be known until experi- 

 ments have been made correlating- the amount of the ditlerent salts 

 in the soil upon Avhicli the dilt'erent varieties grew, Avith their resist- 

 ance in pure solutions. 



Some interestino- diti'erences can 1)e noted here between the resist- 

 ance of wheat and of lupines to sodium sulphate. The Preston vari- 

 ety is -ij times as resistant, and Zimmerman and Kubanka Of times 

 as resistant, as Lupiims cdbus, the toxic limit of the latter having 

 been established by Kearney and Cameron at 0.0075. They found 

 sodium sulphate more toxic to Lupinus than sodium bicarbonate, 

 while for every variety of wheat in these experiments the reverse 

 is true. AVith maize Kearney showed that the seedling would sur- 

 vive equally w^ell in both salts, and established the limit at 0.05 of 

 a normal solution. 



Hilgard states that few plants can bear as much as 0.1 per cent in 

 the soil of sodium carbonate, or about 3,500 pounds per acre to the 

 depth of 1 foot. For sodium chlorid the limit in the soil is about 

 0.25 per cent. In the case of sodium sulphate, most plants can grow 

 in the presence of 0.45 to 0.50 per cent in the soil. In view of this 

 fact sodium chlorid under soil conditions would seem to be more 

 toxic to most plants than the sulphate. 



Stewart " has made a number of interesting tests on the power of 

 seeds to germinate in the presence of sodium carbonate, sodium sul- 

 phate, and sodium chlorid. He found the carbonate and the chlorid 

 to be more injurious than the sulphate. With one exception (rye 

 seeds in the presence of the chlorid), 0.50 per cent of either carbonate 

 or chlorid j^roved fatal to germination. Stewart showed that sodium 

 sulphate is far less injurious than either of the other salts. The 

 character of his experiments indicates, however, that they are not 

 directly comparable with such as are here described. His seeds were 

 l^laced for germination in sand on tin plates and watered, the nature 

 of the water used not being stated. Kearney and Cameron have 

 shown that these salts are decidedly different in the degree to which 

 their toxic effect can be neutralized by the addition of other salts, 

 such as the chlorid or sulphate of calcium. It is possible that the 

 sand ol- the water, or both, used by Stewart contained more or less 

 calcium salts. The results of Kearney and Cameron, above referred 

 to, show that the toxic effect of sodium carbonate, and next to it that 

 of sodium chlorid, are neutralized far less effectively by calcium sul- 



" Effect of Alkali on Seed termination. Ninth Annual Report, Utah Agricul- 

 tural Experiment Station, p. 2(3 (1898). 



