80 General Care of Trees 
A nitrogenous fertilizer, or an occasional dressing with 
hardwood ashes, which contain the required minerals in 
most accessible form, is to be recommended wherever the 
vigor of the tree is impaired. A dressing of ten pounds of 
ashes per hundred square feet, costing perhaps twenty 
cents, will be found very ample. 
Although in most cases hardwood ashes are as good a 
fertilizer as need be, for very impoverished soils the follow- 
ing mixture will be found serviceable and should be applied 
in early spring before the leaves unfold, namely, one pound 
of nitrate of soda, five pounds cotton-seed meal, two pounds 
acid phosphate, two pounds muriate of potash, the whole 
mixed together just before using; one pound of this mixture 
costing, if prepared in quantity, less than two cents per 
pound, will suffice for a hundred square feet. ‘This is also 
an excellent top dressing for lawns. 
The growing of a crop of clover, alfalfa, lupine, or some 
other similar crop and plowing it under while green, is also 
an excellent means of recuperating impoverished soil both 
physically and chemically, and at the same time improving 
its aération. 
While lawns are benefited by sheep, cow, and horse ma- 
nure, and some flowering shrubs respond to treatment with a 
compost made of bone dust and manure, or better still, 
with leaf-mold, the physical improvement of the soil for 
water conduction by stirring and mulching, as advised in 
the preceding pages, is usually all sufficient for arborescent 
growth. 
Points in Grading. One of the most common mistakes 
causing the loss of many old trees, is the filling up of 
ground over the roots in grading operations, by which water 
and still more surely the necessary air is excluded. This 
careless burying of the roots shows inexcusable ignorance 
