Nov.4. i9i8 Soil Factors Affecting the Toxicity of Alkali 307 



on the basis of the dry soil, but the moisture content varied. In the 

 second, the soils were made up with different amounts of the same solu- 

 tion, the concentration being maintained by adding water as it was lost 



HaCL in /ap m. of dry soil 

 400 1000 ZfiOQ J.000 4,000 



moisture ^^j:;KlJKLAlJK.J\..yKy^ 



moisture ^^^Jp^^^^^^^^^ly^Z^^'^y^ 

 moisture v^**/^^^^'^'^ — -' 

 moisture ^5 



• w cne plant ^"■— ■« ai gm drf matter 



12 f, 



moisture 



HoiCOj in p.fim of dry soil 



JfiOO 



5,000 



ipoo 



lopoo 



\^M*/<jMiy<y^ 



» «> ent plant 



' ^ o./ym try matter 



/lotSO, in p.p. m of dry soil 



500 1.000 Jfioo Spoo wo «!**' 



moisture ^^^^kzMlkSKjKjkJ^ 

 moisture ^^^^^^^^Jy^H^^^b^^Zir^ZSMy^^ 



20% 



moisture 



moisture ^^^^^y^*^f^^^b^^^^^ll^^^^y^^^ 



• — «/!» plant ^n^ -moigfn dr-y mafttr 



Fig. 19— Diagram showing the number of wheat plants up and the dry matter produced in 21 days m 

 loam maintained at different moisture contents and containing sodium chlorid, sodium carbonate, and 

 sodium sulphate in various concentrations. 



by evaporation. This would give theoretically the same concentration 

 of salt in each case even though the percentage of moisture was varied. 

 The results are given in Tables III and IV. These show that with soils 

 having the same concentration of salts on the dry soil basis, the greatest 

 83814°— 18 4 



