70 THE ROYAL SOCIETY OF CANADA 



Considering that the sodium sulphate in this group would have 

 no material effect on the crop, it may be concluded tentatively that 

 •25 per cent sodium carbonate marks an extreme limit for vetch and 

 rye. 



Group 1699. No growth. Surface appearance of alkali. Nature 

 of soil: "A," dark brown fine sandy loam with pebbles, moist, showing 

 slight efflorescence on drying; "B" and "C," sand, with very little 

 clay or silt, rather dry; "D" not collected owing to hard pan at 22 

 inches. 



Failure of crop growth in this case appears to be due chiefly to the 

 effect of sodium sulphate, which in "A" reaches approximately 1 per 

 cent. The sodium carbonate present in "A," -056 per cent, although 

 not negligible, can only be acting as a contributory factor. 



Detailed discussion of these and previously reported data for the 

 purpose of establishing limits of tolerance will be postponed until 

 further evidence has been obtained. Satisfactory progress has been 

 made, but the difificulty and importance of the problem involved 

 demand more investigatory work before final conclusions can be 

 safely drawn. 



The soil samples of the several series now reported on were 

 collected and the field notes thereon written by Mr. E. A. Smith, M.A., 

 the joint author of the two papers on this subject previously presented 

 to the Societv. 



