312 



Journal of Agricultural Research 



Vol. XV, No. 5 



unknown factor caused a variation in all samples from day to day, but 

 on each day the relation between the check and the treatment was con- 

 sistent. It was found that the depression of the freezing point varies con- 

 sistently with the concentration and that duplicate samples checked to 



Do CI in p. p. m- of dry soil 



^00 1.000 Z.00O J.OOO 4.000 



so% 

 moisture ^ 



rnoisture ^ 



ZTH 



moisture 



moisture ^^f^^^yh^zy^^^^^^y^^^^^:^^^::^^ 



J4?S 



moistiirf. \^j\j\^sijA^rf^ _ 



' one plant ^^^ = o-igm-d/y matter 



20f. 

 moisture 



2JV. 



moisture 



moisture 



j/% 

 moisture 



moisture 



HojCOj in p.p. m. of dry soil 



SOO 1.000 JjOOO 5P00 7,000 



one plant 



o-iqm- dry matter 



10000 



Po^SO^ in p.p. m. of dry soil 



O SOO 1.000 J.OOO J.000 7,000 lODOO 



zor. 

 moisture ' 



moisture 



Zl.'Z, 



moisture K^'tJ^m 



JITS 



moisture ' 



J4 % 



moisture \»>tj^*/ 



• •■ one plant ^^" = o.iqm- dry matter 



Fig. 23. — Diagram showing the number of wheat plants up and the dry maUer produced iu 21 days in 

 sand and clay maintained at different moisture contents and containing sodium chlorid, sodhmi 

 carbonate, and sodium sulphate in various concentrations. 



within o.oi or 0.02 degree. The freezing point of soils used in preparing 

 figures 2,3, and 4 was taken, and the results were averaged for the differ- 

 ent content of each salt and for the different types of soil. The results 

 are given in Tables V, VI, and VII, which show the quantity of the salt 



