CROPS AND
METHODS FOR SOIL
IMPROVEMENT

By

ALVA AGEE, M.S.

HEAD OF DEPARTMENT OF AGRICULTURAL EXTENSION
ACTING DEAN AND DIRECTOR OF THE SCHOOL OF
AGRICULTURE AND EXPERIMENT STATION OF
THE PENNSYLVANIA STATE COLLEGE

ILLUSTRATED

New York
THE MACMILLAN COMPANY

Nitrogen, phosphoric acid, and potash are the three substances that may not be in available form in sufficient amount for a growing crop. The lack may be in all three, or in any two, or in any one, of these plant constituents. The natural strength of the soil includes the small percentage of these materials that may be available, and the relatively large stores that nature has placed in the land in inert form as a provision against waste.

The thin covering of the earth that is known as the soil is disintegrated rock, combined with organic matter. The original rock "weathered," undergoing physical and chemical change. A long period of time was required for ....................

 

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