290 Journal of Agricultural Research voi. xv. No. s 



EFFECT OF SIZE OF SOIL PARTICLES 



The first factor to be examined was the effect of the size of soil parti- 

 cles on the toxicity of alkali. For this purpose pure quartz sand graded 

 into five sizes was used. The experiment was repeated three times in 



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Fig. 3.— Diagram showing the number of wheat plants up and the dry matter produced in 21 days in soils 

 of different texture containing sodium carbonate added in various concentrations. Moisture content 

 maintained at 20 per cent throughout. 



two different years, twice at 20 per cent moisture and once at 10 per cent. 

 The details of the make-up of the tumblers and the results are shown in 

 figure I. 



