CARING FOR SHADE TREES 
i33 
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 % 
