866 



Journal of Agricultural Research 



Vol. VI, No. 22 



mately the same toxic effect when the total of the carbonate salts recov- 

 erable is considered rather than the percentage of salts added to the soil. 

 In other words, the toxicity of these salts in the soil is directly associable 

 with the quantity of the basic radical in the salt recoverable. The close 

 relationship between the results of these two experiments is shown in 

 figure 6, in which the curves of decrease in growth are constructed on 

 the same scale. 



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/=£T/? GFA/T SALTS //V SO/L AT £TA/D 0/= £X/=>£:f?/MEA/T. 



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Fig. 6. — Diagram of the decrease in growth of wheat seedlings in experiments 2 and 4 as affected by the 

 total carbonate salts recoverable from the soil. The solid black line on the left at each series number in- 

 dicates the percentage of sodium carbonate added to the soil; the line at the right shows the percentage 

 recovered at the end of the experiment. The solid portion of the line shows the carbonate and the 

 hatched portion the bicarbonate. The curve at the right of the figure shows the relative growth of the 

 plants in each series of pots. 



EFFECT OF SODIUM CHLORID ON WHEAT SEEDLINGS 



Experiment 5. — At the same time the carbonate and bicarbonate 

 experiments in 1914 were in progress (experiments 2 and 4) a similar 

 experiment with sodium chlorid was carried on with the same soil. The 

 general plan and manipulation was the same as has been described above. 

 The wheat was allowed to grow for 16 days. The original soil contained 

 only 0.006 per cent of sodium chlorid. 



A summary of the results obtained in this experiment is given in Table 

 V. It is possible to compare these results directly with those obtained 

 in the carbonate, bicarbonate, and sulphate experiments in 1914, as the 

 soil used was the same in all cases. 



