BLACK WALNUT ! ITS GROWTH AND MANAGEMENT. 43 
ever, should be protected from grazing for a period sufficiently long 
to allow the trees to become reasonably safe from damage. The 
period of protection from hogs should be about three years ; from 
cattle and horses, not less than 10 years. The farmer should, how- 
ever, be cautious: and, if grazing that has been started in a planta- 
tion at the end of the tentative period of protection appears to be 
damaging the trees, the stock should be removed for a year or two 
longer. Damage from grazing results more from breakage of the 
trees and from trampling and compacting of the soil than from 
actual browsing. In one plantation in Indiana, for example, there 
is a large opening which resulted from the feeding of corn to hogs, 
a procedure that was continued through many years. The excessive 
trampling and compacting of the soil, together with the unusually 
large accumulations of manure at one place, killed out the trees. 
By wallowing in the depressions about the trees and laying bare 
the roots, hogs occasionally damage trees planted in low, moist parts 
of pastures. For this reason trees planted singly in pastures should 
be set on the slight rises or slopes rather than in the hollows. On 
account of the better drainage these sites dry off quickly after rains, 
instead of holding pools of water or mud about the roots of the trees, 
and consequently they provide better shade places for cattle. 
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