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should be seriously considered as a permanent system on an alkali 

 soil, no matter what the texture, is the installation of under- 

 ground drains, for which purpose, so far, cylindrical tile drains 

 commend themselves as giving the best results. With a well 

 established system of tile drains, the alkali and all excess of 

 soluble salts can be removed from the soil above the drains; 

 and alkali rising from the soil below can, at least very largely, 

 be prevented from rising to the upper soil layers. The reclama- 

 tion of an alkali tract by underdrainage is not, however, a nec- 

 essarily quick operation. Generally it must be a matter of sev- 

 eral years persistent and careful effort, but once attained should 

 readily be maintained. The reclamation of an alkali tract by 

 flooding and underdrainage involves the reverse process to the 

 crystallization of salt from a brine. If the water in percolating 

 through the soil were long enough in contact with the salts 

 present to become a saturated solution in equilibrium with them, 

 then the composition of the resulting solution or drainage water 

 would depend upon the particular solid phases or salts which 

 are present in the soil, but not on the amounts of these salts; 

 and the relative proportions of the mineral constituents in the 

 drainage water should remain constant until some one of the 

 solid phases in the soil permanently disappears. 



In practice, however, the water passes through the soil at 

 different rates from time to time, the flow from the tiles being 

 copious after a flooding but gradually diminishing as time goes 

 on. One or both of two processes can therefore take place. 

 The water may dissolve some of the salts without at any time 

 or place becoming saturated. As the different salts have differ- 

 ent rates of solution as well as different absolute solubilities, 

 it would be expected that not only the concentration of the 

 drainage water, but the composition of the dissolved salts would 

 change from time to time. On the other hand, a part of the 

 water may be imagined to percolate slowly through the finer 

 openings, thus forming a saturated solution with respect to the 

 alkali salts which solution, however, will be diluted on entrance 

 to the drains by a part of the water going through the larger 

 soil openings and dissolving but little salt in its passage. In 

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