3o6 Journal of Agricultural Research voi. xv, no. s 



EFFECT OF MOISTURE CONTENT 



In order to test more completely the effect of different moisture con- 

 tents on the toxicity of the alkali salts, a separate series of experiments 

 was conducted using many of the soils used in the other experiments at 

 different moisture contents. These varied between the lowest and 

 highest extremes at which seeds could be made to germinate. 



rioCI in pp. m- of dry soil 



^00 1,000 2000 J.000 ^00 



moislure tLMzKj<LJKjKjKj^J^^ 



moisture 



• = one plant ■ = o-i^mdry matter 



Po; COj In p.p. m- of dry soil 



SCO 1.000 J.000 JO DO 7.0CO tOflOO 



I J 7. 

 moisture ^^^^ja^^^^/^^^^^' 



207. 



moisture 



2J% 



moisture 



©o©oex:xxxxxx) 



• = one plant «■■" =^ o-njm dry matter 



riOji 5 Of in pp. m of dry soil 



500 1,0 00 J.OOO .\000 7.000 lODOO 



moisture fe)^JCJC_AJUwLJLXJLJw 

 moisture ^3*^^^3^5i^'^!>^ll>VA_A_A_,^^^V_^ 



■20% 



moisture 



moisture Vl/l!>O^^A.^A^!AlA_A^.A^^A_^^y 



• = one plant i == o-iqm dry matter 



Fig. i8. — Diagram showing the number of wheat plants up and the dry matter produced in 21 days in 

 sand and loam maintained at diflcrcnt moisture contents and containing sodium chlorid, sodiimi car- 

 bonate, and sodium sulphate added in various concentrations. 



The results which are given in figures 17 to 26 show that the resist- 

 ance was increased with the increased moisture content up to the point 

 of excessive moisture for plant growth. This was the most noticeable 

 correlation observed in all these investigations. Two additional series 

 were conducted on the plan of duplicating tumblers and using only four 

 concentrations. In the first, the salt content of each set was the same 



