" X.--Atmospheric Fertilizers, 197 " XI.--Recapitulation, 203 SECTION FOURTH. MECHANICAL CULTIVATION. CHAPTER I.--Mechanical Character of the Soil, 209 " II.--Under-draining, 211 " III.--Advantages of Under-draining, 217 " IV.--Sub-soil Plowing, 232 " V.--Plowing and other modes of Pulverizing the Soil, 239 " VI.--Rolling, Mulching, Weeding, etc., 245 SECTION FIFTH. ANALYSIS. CHAPTER I.--Nature of Analysis, 259 " II.--Tables of Analysis, 264 THE PRACTICAL FARMER, 279 EXPLANATION OF TERMS, 287 SECTION FIRST. THE PLANT. CHAPTER I. INTRODUCTION. [What is the object of cultivating the soil? What is necessary in order to cultivate with economy? Are plants created from nothing?] The object of cultivating the soil is to raise from it a crop of _plants_. In order to cultivate with economy, we must _raise the largest possible quantity with the least expense, and without permanent injury to the soil_. Before this can be done we must study the character of plants, and learn their exact composition. They are not _created_ by a mysterious power, they are merely made up of matters already in existence. They take up water containing food and other matters, and discharge from their roots those substances that are not required for their growth. It is necessary for us to know what kind of matter is required as food for the plant, and where this is to be obtained, which we can learn only through such means as shall separate the elements of which plants are composed; in other words, we must _take them apart_, and examine the different pieces of which they are formed. [What must we do to learn the composition of plants? What takes place when vegetable matter is burned? What do we call the two divisions produced by burning? Where does organic matter originate? Inorganic? How much of chemistry should farmers know?] If we burn any vegetable substance it disappears, except a small quantity of earthy matter, which we call _ashes_. In this way we make an important division in the constituents of plants. One portion dissipates into the atmosphere, and the other remains as ashes. That part which burns away during combustion is called _organic matter_; the ashes are called _inorganic matter_. The organic matter has become air, and hence we conclude that it was originally obtained from air. The inorganic matter has become earth, and was obtained from the soil.