Atmospheric manures cost nothing, and are of great value when properly employed. In consequence of this, the soil which is enabled to make the largest appropriation of the atmospheric fertilizers, is worth many times as much as that which allows them to escape.
SECTION FOURTH.
MECHANICAL CULTIVATION.
CHAPTER I.
THE MECHANICAL CHARACTER OF SOILS.
What is the first office of the soil?
How does it hold water for the uses of the plant?
How does it obtain a part of its moisture?
The mechanical character of the soil is well understood from preceding remarks, and the learner knows that there are many offices to be performed by the soil aside from the feeding of plants.