328 
Journal of Agricultural Research 
Vol. XXIV, No. 4 
sodium carbonate also increases somewhat as the concentration of the 
sulphates increase. It is curious that this divergence should be appre¬ 
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ViG. 8—Diagram showing the effect on the growth of wheat plants of adding sulphates in various pro¬ 
portions to Greenville loam already impregnated with sodium carbonate. The maximum concentra¬ 
tions of the individual sulphates are given in the text. 
any toxicity, and as this condition does not obtain in the other trials it 
may be. due to experimental error in this case. The data are not exact 
enough to permit quantitative relations to be drawn with certainty, 
but tiiey seem to indicate that when 5,000 parts per million or more of 
