ILLINOIS TREES: SELECTION. PLANTING, AND CARE 



19 



vide adequate drainage with holes made by a soil auger or 

 through fissures made by compressed air or dynamite. Fill holes 

 made by a soil auger with gravel. 



It is advisable to tile-drain holes for large trees. In clay soil, 

 a single 3- or 4-inch standard agricultural tile drain across the 

 bottom of the hole is adequate if the hole is not over 6 feet in 

 diameter (Fig. 14 and 17). For larger holes and for evergreens, 

 which in general require better drainage than deciduous trees, 

 two lines of tile are recommended (Fig. 16). The tile should lead 



Fig. 16. — Holes for 

 planting trees with 

 balled roots should be 

 2-3 feet wider than the 

 soil ball and they should 

 meet the other specifi- 

 cations given in Fig. 14. 



RAVEL 



Fig. 17. — Effective drainage of holes not over 6 feet in diameter can 

 be obtained with a single tile drain across the bottom. Place enough gravel 

 in the hole to cover the tile. 



