Nov. 4. 1918 Soil Factors Affecting the Toxicity of Alkali 291 



The size of particles alone, as shown by the quartz sand, seemed to 

 have no appreciable effect on the toxicity of tlie salts. The different 

 moisture content shows a marked difference here as elsewhere. The 

 results with sand are the only ones showing the carbonate more toxic 

 than the chlorid on the basis of the amount of salt added. 



flo^SO^ inp.p.nn-ofcjryso'il 

 soo 1,000 J.000 6.000 7.000 10000 



sand 



sand- 90% 

 loom- to % 



sand- 60?. 

 loam-zoi.^ 



6ond- 70'^. 

 loam-joi', 



sand -eon, 

 loam-'tov, 



sand- JO'^ 

 loam-60'f. ' 



sand- ■90% , 



l0Qm-6O< 



Zoom- 70 -i \^3Vl5A;5AlAi»^<^^ 



sond-20^. 

 Joom-oQ-fc 



loom 



loom- 10% 

 cloY-wi 



loam-BO^. 

 c/ay-20% 



loom- 70'% 

 cloy- JO ■X, 



ham- 60 f. 

 cloy- 40< 



loom- 40 f. 



clay - 6o^c \^^^;^^^A^j^/^^ 



loom - - 7 /I •/- fi7i^i<7iy£7it~,^ 



cloy- 70 < 



loam -lo-f. 

 cloy- ^ov. 



cloy 



• = one plant — •— = c-i^mdry motter 



Fig. 4. — Diagram showing the number of wheat plants up and the dry matter produced in 21 days in soils 

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

 maintained at 20 per cent throughout. 



As a continuation of the study of the effect of size of particles or tex- 

 ture, various combinations were used, including soils varying from sand 

 through loam to a brickyard clay. The loam contained more organic 

 matter than either of the others. This condition is usually found in 

 83814°— 18 3 



