284 



SOILS PHYSICS AND MANAGEMENT 



at the surface of the soil or near the root crown. The bark is 

 turned to a brown or black color for about a half inch and may 

 easily be peeled off. In other words, the plant has been " girdled." 

 If the plant does not die it becomes unprofitable. 



The roots are not injured perceptibly to any depth, as a general 

 rule, but it is very likely that the entire plant is poisoned more or 

 less. It is only where common salt is very abundant in the subsoil 

 that the deeper roots are injured. 



Limit for Germination and Growth. Germinating plants are 

 most sensitive to alkali, hence a comparatively small amount in the 



Highest Amount of Alkali in Which Plants Weie Found Unaffected* Arranged 

 from Highest to Lowest. Pounds Per Acre Four Feet Deep 



surface soil at that period may produce very serious results. As an 

 illustration, young alfalfa will not stand more than 13.000 pounds 

 of alkali hi the soil to a depth of four feet, while old alfalfa will 

 flourish where nearly ten times that amount exists, and this is true 

 more or less of all plants. 



In the growing of certain crops special methods are employed 

 for reducing the amount of alkali in the surface soil until the plant 

 becomes old enough to resist its effect. All plants are not equally 

 injured by the same amount of alkali. Some will grow and flourish 

 where others will die. In the case of the tussock grass, it will grow 

 where the soil to a depth of four feet contains 499,000 pounds of 



