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CHAPTER II. 

 MANURES CONSIDERED WITH REFERENCE TO HORTICULTURE. 



THE improvement of the composition and the texture of a soil, and of 

 its condition with reference to water and heat, will have but little 

 effect on the plants cultivated in it, without the addition of manure. 

 In order to determine what substances are suitable for becoming 

 manures, it is useful to know what are the constituent elements of 

 plants. Of these we shall find that some elements are common to all 

 plants whatever, such as carbon, with oxygen and hydrogen in the 

 proper relative proportions for forming water, and nitrogen ; while 

 some elements are only found in particular plants, such as certain 

 salts, earths, and metallic oxides. Every plant, therefore, may be said 

 to have its general or common food, and its specific or particular food ; 

 and hence, in this point of view, manures may be classed as common 

 and specific. The most perfect manure for any plant would therefore 

 seem to be, that plant itself in a state of decomposition ; but as the 

 purpose for which plants are cultivated is to supply food, clothing, and 

 various other necessaries for men and animals, hence, in a state 

 of civilization, it is among these, and from animals themselves, that 

 we must seek for the most suitable manure for plants. The various 

 substances which have been used for manures may be classed, with 

 reference to their effect on plants, as general and specific ; and with 

 reference to the soil, as improving, enriching, and stimulating. Im- 

 proving manures are such as, while they afford positive nourishment 

 or stimulus, add some permanent matter to the soil ; such as lime, 

 chalk, marl, bones, &c. Enriching manures are such as supply only 

 nourishment to plants ; such as stable manure, and every description 

 of organic matter ; and stimulating manures are such as serve to aid 

 in the decomposition of, or otherwise operate on, the organic matter. 

 As some manures, however, partake in an equal degree of more than 

 one of these properties, such as lime, which is both a stimulating and 

 improving manure, the most convenient arrangement of manures will 

 be organic, inorganic, and mixed. 



Organic Manures. 



Organic manures must obviously be either of animal or vegetable 

 origin. Purely vegetable manure is exemplified in leaf-mould, malt- 

 dust, rape-cake, spent tanner's bark, some kinds of peat, and green 

 vegetables when they are buried in the soil in a living state. 



Leaf-mould is perhaps the most universal manure for garden plants, 

 because, when thoroughly decomposed, the most tender kinds will live 

 in it, and all the more vigorous-growing vegetables will grow in it 

 most luxuriantly if it be mixed with fine sand. The sand seems 



