196 CROPS FOR ALKALI LAND 



certain kinds of alkali, but as long as the yiqld is sufficiently 

 high to prove economical when used for any purpose con- 

 ditions may warrant the use of such a crop in preference 

 to crops not injured materially by the alkali but which 

 do not fit economically into the cropping system. 



Where the main object is to reclaim land quickly and 

 put it in condition for the common crops, it is frequently 

 desired to green manure the land, to get good aeration of 

 the soil, to retain a mulch, and to keep all moisture moving 

 downward. For such purposes where the soil contains 

 salts in quantities so large that most ordinary crops fail, 

 sorgo, rye, millet, barley, rape, kale, and a few other high- 

 resistant crops which yield a large quantity of dry matter 

 are used. When the alkali content does not exceed about 

 5000 parts per million of white alkali, less resistant but 

 more desirable legume crops (sweet clover, alfalfa, Canada 

 field peas, vetch, and horse beans) should be preferred to 

 the above crops, provided the seed-bed can be prepared 

 so that a good stand may be secured. 



Tolerance of Alkali by Various Crops. In studying 

 the figures given for the quantities of salts that various 

 crops have been found to endure safely, it should be kept 

 in mind that the character of the plants, feeding system 

 in relation to the alkali, and the nature of the soil as above 

 mentioned will often cause enormous differences with the 

 same plant. Soil, moisture, climate, and perhaps other 

 things will often change the relative tolerance of the dif- 

 ferent crops to some extent so that slight differences in 

 tolerance mean little or nothing. Unless otherwise men- 

 tioned, the salt as given is understood to be the proportion 

 found in the soil to a depth of four feet. Although this 

 arbitrary unit will be misleading when the concentration 

 of the salts varies at different depths in the soil, as is often 



