224 THE LURE OF THE LAND 



destroy the chestnut groves of the United States, 

 namely, the chestnut blight, which, taking its origin in 

 the northeast, has already reached northern Virginia. 



It is possible that the artificial planting of many of 

 these valuable trees, especially the leguminous vari- 

 eties, such as the locust, might be interspersed with the 

 terracing of the surface so that the two might work to- 

 gether for holding the soils. The locust enriches the 

 soil where it grows by increasing its store of nitrogen. 

 The new embankment of the terrace might, therefore, 

 be planted with rows of locust trees, which permit 

 cultivated crops to be grown close up to their trunks. 



All of these methods of restraining the action of 

 water naturally tend to hold the water in the locality 

 where it falls, and thus to increase the amount avail- 

 able a^s soil moisture for crop growth. It would of 

 course be disastrous if water could be so held that it 

 never would percolate. The soluble materials which 

 come from the decay of rocks in the form of alkaline 

 compounds would so increase, if there were no under- 

 drainage, as to produce everywhere in the course of 

 many years that condition which is called alkaline, and 

 which in excess is so fatal to plant growth. It appears, 

 therefore, that among the various methods which have 

 been recommended for the control of soil erosion, espe- 

 cial attention should be paid to reforestation in gen- 

 eral or to reforestation with crop-producing trees in 

 particular. 



But this is not sufficient. Restitution must be made 

 for the robbery of the past. If the land has been re- 

 duced to the very lowest degree of penury, it is neces- 

 sary to purchase, in order to begin its restoration, 

 additional quantities of phosphoric acid, potash and 

 nitrogen. With this purchase of plant foods a new 



