It is a matter of almost universal remark, that in our climate soils are fertile—clayey or loamy soils, that is—only when they contain an appreciable quantity of lime. In whatever way it acts, therefore, the mixing of lime in any of the forms above mentioned, with a soil in which little or no lime exists, is one of the surest practical methods of bringing it nearer in composition to those soils from which the largest returns of agriculture produce are usually obtained. Some of the chemical effects of the lime upon the soil will be explained in a subsequent section. (See page 195.) SECTION II.—OF THE CHEMICAL METHOD OF IMPROVING THE SOIL BY THE USE OF MANURES. None of the above methods of improving the soil are mechanical only—they all involve some chemical alterations also, which are readily to be explained by a knowledge of elementary chemical principles. But the manuring of the land is more strictly a chemical operation, and may therefore with propriety be separated from those methods of improving its quality which involve at the same time important and expensive mechanical operations. In commencing the tillage of a piece of land, the conscientious farmer may have three objects in view in regard to it. 1. He may wish to reclaim a waste, or to restore a neglected farm to an average condition of fertility. 2. Finding the land in this average state, his utmost ambition may be to keep it in its present condition; or, 3. By _high_ farming he may wish to develope all its capabilities, and to increase its permanent productiveness in the greatest possible degree. The man who aims at the last of these objects is not only the best tenant and the best citizen, but he is also his own best friend. The highest farming, skilfully and prudently conducted, is also the most remunerating. But whichever of these three ends he aims at, he will be unable to attain it without a due knowledge of the various manures it may be in his power to apply to his land—what these manures are, or of what they consist—the general and special purposes they are each intended to serve—which are the most effective for this or that crop—how they are to be obtained in the greatest abundance, and at the least cost—how their strength may be economized,—and in what state and at what seasons they may be most beneficially applied to the land. Such are a few of the questions which the skilful farmer should be ready to ask himself, and should be able to answer. By a _manure_ is to be understood whatever is capable of feeding or of supplying food to the plant. And us plants require earthy and saline as well as vegetable food, gypsum and nitrate of soda are as properly called manures as farm-yard dung, bone-dust, or night-soil. Manures naturally divide themselves into such as are of _vegetable_, of _animal_, and of _mineral_ origin. I. OF VEGETABLE MANURES.