CARING FOR SHADE TREES 133 



Akin to watering, and closely related to it in impor- 

 tance, is cultivation of the soil at the base of the tree. 

 The ground must be kept free from weeds and sufficiently 

 loose to permit air to reach the roots. Loose soil holds 

 moisture much better than soil which is allowed to pack 

 and form a solid surface. Closely packed soil causes the 

 moisture to rise to the surface and evaporate, while loose 

 soil gives the roots the full benefit of it. Lack of cultiva- 

 tion of the soil may be set down as one of the most frequent 

 causes of failure in the growing of trees. On the other 

 hand, careful and oft-repeated cultivation will often insure 

 success where the handicaps of environment are most 

 serious. Constant cultivation is needed during the first 

 summer of the young tree in its new location. To accom- 

 plish this, the soil should be kept well crumbled to a depth 

 of three or four inches, in an area extending from the base 

 of the tree as far as the roots reach. 



The nourishment taken from the soil by root absorp- 

 tion may be augmented to good advantage by covering 

 the surface around the base of the tree in the autumn 

 with mulch containing well-rotted manure. In the spring 

 this should be turned into the soil, where it serves the 

 double purpose of furnishing added nourishment and 

 of rendering the soil more porous. Instead of the manure, 

 chemical fertilizer may be used, but it lacks the organic 

 matter contained in manure. A good mixture for most 

 trees in light soil is made up of equal proportions of 

 nitrate of soda, acid phosphate, muriate of potash and 

 ground bone. This should be applied in the spring 

 with the exception of nitrate of soda which should be 

 applied only when roots are active. The amount required 

 for the individual tree will be from 1 % to 2 ounces of 

 the mixture for a tree occupying a space of 8 square 

 feet. If the nitrate of soda is applied separately % to % 



