78 General Care of Trees 
ings or leaves should be added. If this is done in the fall 
the tree will be invigorated with new life, the winter moist- 
ure will penetrate, and new rootlets will form in larger 
numbers, for root activity continues long after the fall 
of leaves. In the spring the sod may be re-established, 
although badly starved trees will be benefited by keeping 
them mulched for a few seasons. The mulch should not 
be too thick, just enough to prevent the pattering rain from 
compacting the soil, and to prevent evaporation from it; 
this may be attained by a cover not heavier than one-half 
to one inch. Nor should the mulch be allowed to become 
compacted itself, so as to impede free penetration of water 
and air. 
There is not much value in making this application close 
around the stem; it is under the trough of the outer foliage, 
under the ambitus of the crown, that the main feeding root- 
lets are located, and here the treatment will most benefit 
the patient. 
On shallow and very compact clay soils this treatment 
should be frequently repeated, and possibly at the same 
time some sand or garden mold should be worked into the 
soil, or else an application of lime, marl, or gypsum may be 
made, which-has the effect of granulating a stiff soil, making 
it porous and thus improving its water-conducting capacity. 
The application of slacked lime, as free as possible from 
magnesia, should be made during the winter in small re- 
peated doses at the rate of about one to three pounds per 
hundred square feet. 
Watering, where practicable, will, of course, overcome 
the effects of drouth; but it must be kept in mind that a 
surplus of water may become injurious by reducing aéra- 
tion. Often, the mere loosening of the soil is sufficient to 
correct the deficiency in water-supply: the loose surface 
