ANCHORAGE 



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soil layers and the older parts of the root have lost the ability to 

 absorb. These facts are very important in connection with the 

 addition of artificial fertilizers to soils in which crop plants are to 

 be grown. 



6. Anchorage.— While the function of absorption is limited largely 

 to the smallest roots and especially to the root hairs, anchorage is 

 a function of the entire root system. That root systems in general 

 are efficient in performing this function is shown by the infrequency 

 with which plants are uprooted by the wind. It is seldom that even 

 tall trees are uprooted except when a region is visited by a tornado. 



Fig. 4.— Trees and shrubs checking erosion on a hillside. 



Experiments have shown that healthy corn plants four months old 

 will offer a resistance of 200 to 360 pounds to a straight vertical pull. 

 The efficiency of the root system is well seen also along streams where 

 the banks are being eroded by the water. The root system of a tree 

 may be more than half uncovered and still hold the plant upright. 

 Where trees are growing along streams erosion is much less rapid 

 than where there are few or no plants as the roots tend to hold the 

 soil in place (Fig. 4). In fact usually the simplest way to check 

 erosion in such a place is to plant trees or shrubs. This is equally 

 true of other places where erosion is likely to occur, such as hillsides. 

 Some kinds of plants are much more efficient than others in holding 

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