ALKALI 



ALKALI is a salt or a combination of salts, which, if existing in the soil 

 ■ in excessive quantities, destroys it for agricultural purposes. A very- 

 small per cent of alkali is very essential to plant life; in fact, soil devoid 

 of this salt is not productive. It is estimated that nearly a million acres 

 of the irrigated lands in the west contain enough alkali to render them 

 very unproductive or absolutely worthless for farming purposes. 



Alkali salts are divided into two classes, namely, white alkali and 

 black alkali. 



The white alkali is less harmful than the black. The principal white 

 alkalis are Glaubers salts (sodium sulphate), common table salt (sodium 

 chloride), Epsom salts (magnesium sulphate) and common baking soda 

 (sodium bicarbonate). 



The black alkali is salsoda (sodium carbonate). 



White alkalis either existed in the soil before it was cultivated, or 

 were carried there by irrigating waters. If these salts exist in quanti- 

 ties as gi'eat as one per cent, they exert a deleterious effect upon the 

 plants; however, some very resistant plants thrive where as much as two 

 per cent of alkali exists in the soil. The ability of a plant to thrive in an 

 alkali soil depends upon the amount of water holding the salt in solution 

 and the location of the salt. Alkalis are carried to the surface by water 

 through the process of evaporation, and they are driven down by the 

 water into the deeper subsoils when it is applied in excessive quantities. 

 They are destructive to plants when on or near the surface, but when in 

 the deeper soil in solution, they are less harmful. 



Black alkali is a very corroding destructive salt, and if it exists in the 

 soil to the extent of one-tenth of one per cent or more, it is destructive 

 to plant life. 



White alkali appears in a thin film or crust on the surface. 



Soil containing black alkali has black spots or black rings on the surface, 

 the soil is black and puddled, and water standing on the surface is black. 



How to Remedy Alkali Soils 



White alkali can be removed from the soil by washing it out with 

 water either by irrigation or by heavy rains, provided underground 

 drainage is supplied to carry it off. 



Black alkali can be remedied by the application of gypsum (land 

 plaster). If several applications are made, the black alkali is neutral- 

 ized and transformed into a white salt which can easily be washed out. 



Black alkali without the use of gypsum, however, cannot be washed 

 out to any extent. 



Crops 



Certain crops are adapted to soils containing different amounts of 

 alkali. 



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