PREPARING HOLES FOR PLANTING 



105 



between the trees is said to be practicable after the trees are grow.- 

 ing, and may in certain soils relieve trees which are suffering for 

 lack of drainage. A half-pound cartridge of dynamite has been 

 successfully used for subsoil blasting, and some have reported in 

 favor of exploding a quarter-pound cartridge quite near to a tree 

 suffering from standing water, putting in the charge during the dry 

 season. 



There are many situations where such practice would be bene- 

 ficial, and in some cases mere digging or boring through the im- 

 pervious 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, rilling with good soil and planting 

 the trees in these holes. Their roots penetrate to the gravel stratum 

 and obtain abundant moisture 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 hard-pan underlaid by free 

 soils, trees can often be successfully grown by the use of high ex- 

 plosives. In his book on "Soils" Professor Hilgard gives these 

 suggestions : 



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

 moderate charges (y 2 to ^4 lb.) 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 hard pan to a corresponding 

 extent sidewise. If properly proportioned the charge will hardly disturb the 

 surface; but if this be desired, from i l /2 to 2 l /2 pounds of black powder placed 

 above the dynamite will throw out sufficient earth to plant the tree without . 

 farther 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 crop*, where 

 formerly they would not succeed. 



The boring for such blasting is usually with an ordinary carpen- 

 ter's auger, a little larger than the diameter of the cartridge to be 

 used ; the shank of the auger being lengthened by the blacksmith to 

 reach the depth desired. 



It is becoming more and more apparent, however, that for com- 

 mercial plantings of trees and vines all such defective soils should 

 be avoided. There is plenty of good, deep land to be had, and the 

 burden of ameliorating poor land is a serious handicap in the com- 

 petition which has brought production to very narrow margins of 

 profit. 



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 



