* 
oct. 4 ,191 s Effect of Alkali Salts in Soils on Crops 
51 
(9) The anion, or acid radical, and not the cation, or basic radical, 
determines the toxicity of alkali salts in the soil. Of the acid radicals 
used, chlorid was decidedly the most toxic, while sodium was the most 
toxic base. 
(10) The injurious action of alkali salts is not in all cases proportional 
to the osmotic pressure of the salts. 
(11) The toxicity of soluble salts in the soil was found to be in the 
following order: Sodium chlorid, calcium chlorid, potassium chlorid, 
sodium nitrate, magnesium chlorid, potassium nitrate, magnesium nitrate, 
Barley Oats Wheat Alfalfa Sugar beets Com Field peas 
Fig. 48.—Curve showing the percentage of sodium chlorid, sodium carbonate, and sodium sulphate in 
Greenville loam giving about half normal germination and production of dry matter. 
sodium carbonate, potassium carbonate, sodium sulphate, potassium sul¬ 
phate, and magnesium sulphate. 
(12) The antagonistic effect of combined salts was not so great in 
soils as in solution cultures. 
(13) The percentage of soil moisture influences the toxicity of alkali 
salts. 
(14) Salts added to the soil in the dry state do not have so great an 
effect as those added in solution. 
(15) Land containing more than about the following percentages of 
soluble salt are probably not suited without reclamation to produce 
ordinary crops. In loam, chlorids, 0.3 per ojnt; nitrates, 0.4 per cent; 
carbonates, 0.5 per cent; sulphates, above 1.0 per cent. In coarse sand, 
chlorids, 0.2 per cent; nitrates, 0.3 per cent; carbonates, 0.3 per cent; 
and sulphates, 0.6 per cent. 
