INFLUENCE OF SOIL ALKALI ON BACTERIA 199 



much of the alkali when it accumulates at the surface during 

 certain seasons of the year. The scrapings are then carted from 

 the land. 



(3) Some farmers attempt to flood the affected area and 

 quickly drain off the water, hoping that in this way considerable 

 of the surface alkali may be picked up by the water. However, 

 such attempts usually meet with failure because the water which 

 dissolves the alkali usually penetrates the soil and is not subse- 

 quently drawn off. 



(4) The most successful method for reclaiming alkali soil is 

 by the leaching out of the soluble constituents by means of water. 

 In order that this be a success there must be a good underdrainage 

 and the water applied in quantities sufficient to pass down through 

 the soil and carry with it the alkali. This is the only permanent 

 method, as it is the only one which completely removes the cause. 

 Even where the alkalies are washed out it is often a number of 

 years before the soil becomes productive. This is probably due 

 to the absence of the requisite bacterial flora. Moreover, during 

 the leaching out of the alkali much of the available plant-food 

 would also be carried out. Hence, more must be rendered avail- 

 able by later bacterial activity. The period of unproductivity may 

 be greatly shortened by the addition of large quantities of barn- 

 yard manure. 



