3i8 



Journal of Agricultural Research 



Vol. XV, No. 5 



solution was allowed to settle for an hour and filtered through a Pasteur- 

 Chamberland filter. Ten to fifty cc. of the clear solution were titrated 

 with NI50 sulphuric acid, with methyl-orange as indicator and the 

 results expressed as sodium carbonate. In cases where there was much 

 organic matter in the soil the solution was very black, but by diluting 

 with neutral water to a yellowish-brown color the end point could always 

 be distinctly observed by one accustomed to making the titration. It 

 was found that this method gave as nearly complete an extractidn as 



Fig. 27. — Graphs showing the percentage of normal yield of dry matter of wheat produced in 21 days with 

 various concentrations of added sodium chlorid, sodiiun carbonate, and sodium sulphate. Average 

 of all trials. 



any method of cold-water extraction that we could find, but the solution 

 was never complete. Since most field studies are made by water extrac- 

 tions, this may offer a partial explanation of the unusual nature of our 



results. 



SUMMARY 



(i) There is a great need for definite information regarding the toxicity 

 of alkali salts in the soil. 



(2) This paper reports about 12,000 determinations of the effect of 

 alkali salts on plant germination and growth under different conditions. 



(3) Size of particles of a sand independent of other factors does not 

 seem appreciably to influence the toxicity of alkali. 



