THE HANDLING OF THE LAND 111 
addition of this humus makes the land mellow, friable, retentive 
of moisture, and promotes the general chemical activities of the 
soil. It also puts the soil in the best physical condition for the 
comfort and well-being of the plants. Very many of the lands 
that are said to be exhausted of plant-food still contain enough 
potash, phosphoric acid, and lime, and other fertilizing elements, 
to produce good crops; but they have been greatly injured in 
their physical condition by long-continued cropping, injudicious 
tillage, and the withholding of vegetable matter. A part of the 
marked results secured from the plowing under of clover is due 
to the incorporation of vegetable matter, wholly aside from the 
addition of fertilizing material; and this is emphatically true 
of clover because its deep-growing roots penetrate and break 
up the subsoil. 
Muck and leafmold are often very useful in ameliorating 
either very hard or very loose lands. Excellent humous mate- 
rial may be constantly at hand if the leaves, garden refuse, and 
some of the manure are piled and composted (p. 114). If the 
pile is turned several times a year, the material becomes fine 
and uniform in texture. 
The various questions associated with the fertilizing of the 
land are too large to be considered in detail here. Persons who 
desire to familiarize themselves with the subject should con- 
sult recent books. It may be said, however, that, as a rule, 
most lands contain all the elements of plant-food in sufficient 
quantities except potash, phosphoric acid, and nitrogen. In 
many cases, lime is very beneficial to land, usually because it 
corrects acidity and las a mechanical effect in pulverizing and 
flocculating clay and in cementing sands. 
The chief sources of commercial potash are muriate of potash, 
sulfate of potash, and wood ashes. For general purposes, the 
muriate of potash is now recommended, because it is com- 
paratively cheap and the composition is uniform. A normal 
application of muriate of potash is 200 to 300 pounds to the 
