262 FERTILIZERS. 



Direct applications of growing vegetables — straw, tops of potatoes, anil a variety of stalks of 

 vegetables, may be spread over the fields and ploughed in, like a green crop. Upon the sea 

 coast, sea weeds have been largely employed for fertilization : they possess considerable power 

 for the season, but their effects are transient ; they require an annual renewing ; still they are 

 cheap, and should not be neglected, when they are accessible. They are to be employed in 

 the compost heap. The analyses by Johnston give large percentages of potash and soda : 

 sulphuric acid is also abundant ; the phosphates are less, in proportion to the other elements ; 

 they contain much the same elements as the ash of land plants. Sea weed, in consequence of 

 the large quantity of water which is always in combination with it, decays rapidly. Somewhat 

 similar to the sea weed, in its effects, is the common brake, or polypod : there are many species, 

 but they are alike, in their effects upon a grain crop, when ploughed in ; these decompose also 

 rapidly. They may be cut in August, during the rainy weather, carted green into the barn- 

 yard and formed into a compost heap : they may also be spread over a field, to be ploughed 

 and treated in the same way as green crops are treated. All weeds, leaves, saw dust and refuse 

 vegetable matters may be made into a heap, treated with subcaustic lime. They soon become 

 suitable to be employed as fertilizers. 



In all vegetables, both organic and inorganic matter is secured to the crop. The addition 

 of organic matter is often necessary to give effect to the inorganic. It is important in the de- 

 composition of the oxides of iron, and hence, too, is quite necessary to the formation of nitro- 

 gen in the soil. The most favorable of organic bodies in the soil to produce all the results 

 required, both mechanical and chemical, are the roots : these have penetrated deep, as well as 

 widely — occupy almost, if not quite, the whole ground, and hence, too, affect the soil with 

 great uniformity. Carbonic acid is also set free in the course of the chemical changes which 

 organic matters undergo in the soil. Two purposes, at least, are secured, by its liberation ; it 

 is absorbed by water, and enters the tissues of the vegetable ; it also becomes a solvent for the 

 phosphates and the carbonates, and brings them into a state suitable to meet the wants of the 

 plant. Peat, in its green or fresh state, may be ploughed under the soil, when being subjected 

 to a new class of agencies, it is decomposed, like other vegetable matter, and with like results. 



III. Fertilizers from the animal kingdom. 



The substances which belong properly to this class of fertilizers are the solids and fluids of 

 animals, and their excrementitious matters. They differ, in one respect, from vegetable sub- 

 stances — they are far more active in their effects; and what is farther true of them, in part, is, 

 they are more transient in their operation. This is particularly the case with flesh and blood, 

 and all those parts which contain an excess of nitrogenous matter. Bone, hair and horn being 

 composed of less perishable constituents, remain a long time, and yield slowly their aliments to 

 plants ; and in this we find a very valuable property. Their decomposition goes on with suffi- 

 cient rapidity to supply the wants of the various crops to which they are applied, and hence 

 are little subject to waste and loss, when subjected to the ordinary atmospheric agencies. 

 They require to be more or less comminuted, or broken, in order to increaseathe extent of sur- 



