CHAPTER V 



MOVEMENTS OF SALTS IN THE SOIL 



Salts in the Soil Diffusion of Salts Influence of Movements of Water 

 Phenomena of Drainage Waters Alkali Lands Treatment of Alkali 

 Lands. 



Salts in the Soil. The water present in a fertile soil 

 always contains salts in solution ; the quantity of salts dis- 

 solved in the water is usually very small, but their importance 

 for plant nutrition is very great. A part of these salts is 

 annually taken up as plant food by the roots of the crops 

 growing on the land ; a part is also annually removed by 

 percolating water, and is discharged by springs into rivers, 

 and finally carried to the sea. The loss of salts which thus 

 takes place is met by annual supplies. The rain brings 

 small quantities of certain salts to the land. The decay 

 of vegetable and animal matter returns soluble salts to 

 the soil which had previously existed in their tissues. The 

 gradual solution of some of the soil constituents may also 

 considerably increase the quantity of salts present. 



The salts most generally produced in the soil by this 

 process of solution are calcium carbonate, resulting from 

 the solvent action of water containing carbonic acid on the 

 calcareous constituents of the soil, and calcium nitrate, 

 produced during the process of nitrification. The solution of 



