Oct. 4, 19IS 



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 casts 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, 



Above 



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 o«nt; nitrates, 0.4 per cent; 

 carbonates, 0.5 per cent; sulphates, above i.o percent. In coarse sand, 

 chlorids, 0.2 per cent; nitrates, 0.3 per cent; carbonates, 0.3 per cent; 

 and sulphates, 0.6 per cent. 



