ALKALI LANDS AND THEIR RECLAMATION 285 



alkali, while 7000 or 8000 pounds will injure the lemon tree. The 

 preceding table gives the highest amount of alkali in which plants 

 were found unaffected. 



As a general rule plants. cannot withstand more than 0.1 per cent 

 of sodium carbonate or 1(1,000 pounds in a, depth of 4 feet, O.^o per 

 cent or 40,000 pounds of sodium chloride or common salt, nor 

 more than 0.5 per cent or 80,000 pounds of sodium sulfate. If the 

 amounts increase to any extent beyond these, the plants are very 

 seriously injured. 



Utilization and Reclamation of Alkali Lands, The large 

 extent and great value of alkali lands make their utilization and 

 reclamation some of the most important problems in irrigated 

 regions. While a great many methods have been tried with partial 

 success, yet the removal of the alkali is the only remedy that will 

 permanently reclaim the land. It may be well to notice some of 

 the more or less temporary expedients for utilizing these soils. 



1. Growing Alkali-Resistant Crops. All plants are not 

 equally sensitive to alkali, and the problem here is to find the crop 

 of highest value that will be affected least by the salts. The salt 

 grass and salt bushes grow under extreme conditions and they are 

 of considerable value for forage. Sweet clover (Melilot) grows 

 well where alkali is quite abundant and furnishes very good pasture 

 and forage when cut early. In some places it is crowding out other 

 plants. For gaining the requisite knowledge, the kinds and amounts 

 of each alkali must be determined and different crops grown to learn 

 the effects of varying quantities of salts upon them. After getting 

 this information the determination of the alkali of new lands will 

 give a very good idea of the crops to grow. Many plants are most 

 sensitive to alkali when young and some special precautions must 

 he taken in starting them. As a general rule shallow rooting crops 

 are more sensitive than the deeper rooting ones, such as alfalfa and 

 melilot. whose roots extend beyond the /one of greatest concen- 

 tration. 



2. Retarding Evaporation. Alkali salts do most of their in- 

 jury when near the surface. They are brought there by the upward 

 .movement and evaporation of water, and anything that will prevent 



this will retard the accumulation of salts in the /one of greatest 

 injury. This may be done in two ways by mulching and shading. 

 The efficiency of a layer of soil in fine tilth to prevent, evaporation 

 has already been discussed. This should be three or four inches 



