NEUTRALIZATION OF BLACK ALKALI 



317 



and composition of the alkali. The soil must be kept 

 moist, in order to bring about the reaction, and the 

 gypsum should be harrowed into the surface, and not 

 plowed under. 



Fig. 104. Bromus inermis growing on reclaimed alkali land. 



When soil containing black alkali is to be tile-drained, 

 it is recommended that the land first be treated with 

 gypsum, as the substitution of alkali sulfates for carbo- 

 nates causes the soil to assume a much less compact 

 condition and thus facilitates drainage, as well as pre- 

 venting the loss of organic matter dissolved by the alkali 



