BLASTING HOLES FOR TREES 95 



There are many situations where such practice would be beneficial, 

 and in some cases mere digging or boring through the impervious 

 stratum avails much. There are spots where "lava crusts" overlie 

 gravel, and trees have been well grown by cutting holes through the lava 

 to the gravel, filling with good soil and planting the trees in these holes. 

 Their roots penetrate to the gravel stratum and obtain abundant moist- 

 ure and nutriment. In certain situations where a shallow layer of soil 

 overlies a heavy clay, trees have been blown over, but when a cut has 

 been made through the clay, the trees have rooted deeply and have 

 withstood the winds. 



Shooting Holes for Trees. Even where there are continuous 

 depths of dense strata, and not shallow hardpan underlaid by free 

 soils, trees can often be successfully grown by the use of high explosives. 

 In his book on "Soils," Professor Hilgard gives these suggestions : 



A permanent loosening of dense sub-strata is best accomplished by moderate 

 charges (J/ to $4 Ib.) of No. 2 dynamite at a sufficient depth (3 to 5 ft.). 

 The shattering effect of the explosure will be sensible to a depth of eight feet or 

 more, and will fissure the clay or hardpan to a corresponding extent sidewise. 

 If properlv proportioned the charge will hardly disturb the surface ; or will throw 

 out sufficient earth to plant the tree without further digging. Where labor is 

 high priced this proves the cheapest as well as the best way to prepare such 

 ground for tree planting, and it has often been found that in course of time the 

 loosening begun by the powder has extended through the mass of the land so as 

 to permit the roots to utilize it fully and even to permit, in after years, of the 

 planting of field crops where formerly they would not succeed. 



Upon the basis of these pioneer demonstrations, California claims 

 priority in the now widely prevalent "dynamite farming." The most 

 minute descriptions of approved methods are now available in the pub- 

 ILations of the powder manufacturers and their traveling demonstra- 

 tors give field instructions in materials and appliances to those who 

 ask for them. 



It is still a question, however, how for commercial plantings of 

 trees and vines on such defective soils should be undertaken while there 

 is plenty of good, deep land to be had. 



Digging the Holes. Holes for tree planting may be dug at a 

 leisure time after the laying off of the field, even though it is not 

 designed to plant the trees immediately, but our largest planters do 

 not approve the practice. In such cases the sides of the holes should 

 always be freshly pared off before the trees are put in, because the 

 rain and sunshine are apt to cement the sides. In digging holes the 

 surface earth should always be thrown to one side and the lower 

 soil on another. The object of this is to have the top soil to place 

 in direct contact with the roots when the tree is planted, the lower 

 soil being used to fill up the hole with. 



TREE SETTERS 



No matter how carefully the stakes are placed in laying off the 

 orchard, the trees will not easily come in line unless some handy de- 

 vice is used for bringing the stem just in the place occupied by the 

 stake which was thrown out in digging. These devices are called 



