672 



MANURES. 



itself into those primitive elements which can re-enter 

 into the vegetable system). The principal result of 

 tills decomposition is carbonic acid, which, becoming 

 dissolved in water, finds its entrance into the plant 

 by the pores in the fibres of the roots, and, being 

 everywhere distributed through the vegetable tissue, 

 deposits its carbon for the growth of the plant, while 

 its oxygen escapes into the atmosphere, through the 

 pores of the leaves. Manure which lias not com- 

 pletely undergone the process of fermentation, so 

 that the straw is not yet wholly decomposed, is best 

 adapted to strong, compact soils ; the tubular rem- 

 nants of straw answer the purpose of so many little 

 props to support the earth, and afford a passage for 

 the air, thus rendering the soil lighter ; besides, the 

 completion of the fermentation taking place after the 

 manure is buried in the soil, has the advantage of 

 raising the temperature. Those bodies which are 

 subject to the most rapid decomposition, are most 

 employed for manure. Of this description are ani- 

 mal manures in general, which require no chemical 

 preparation to fit them for the soil. The great object 

 of the farmer is to blend them with the earthy con- 

 stituents, in a proper state of division, and to prevent 

 their too rapid fermentation. In maritime districts, 

 fish, when sufficiently abundant, are sometimes vised 

 to manure the land. They afford a powerful manure, 

 and cannot be ploughed in too fresh, though the quan- 

 tity should be limited. Mr Young records an expe- 

 riment, in which herrings, spread over a field, and 

 ploughed in for wheat, produced so rank a crop, 

 that it was entirely laid before harvest. During the 

 putrefaction of urine, the greatest part of the soluble 

 animal matter that it contains is destroyed ; it should, 

 consequently, be used as fresh as possible ; but if not 

 mixed with solid matter, it should be diluted with 

 water, as, when pure, it contains too large a quantity 

 of animal matter to form a proper fluid nourishment 

 for absorption by the roots of plants. Amongst ex- 

 crementitious solid substances, one of the most power- 

 ful is the dung of birds that feed on animal food, 

 particularly the dung of sea-birds. The guano, 

 which is used to a great extent in South America, 

 and which is the manure that fertilizes the sterile 

 plains of Peru, is a production of this kind. It con- 

 tains a fourth part of its weight of uric acid, partly 

 saturated with ammonia, and partly with potash ; 

 some phosphoric acid, combined with the bases, and 

 likewise with lime ; small quantities of sulphate and 

 muriate of potash ; a little fatty matter; and some 

 quartzose sand. Night-soil, it is well known, is a 

 very powerful manure, and very liable to decompose. 

 Its disagreeable smell may be destroyed by mixing 

 with quick-lime, after which, if exposed to the atmo- 

 sphere in thin layers, in fine weather, it speedily 

 dries, is easy pulverized, and, in this state, may be 

 used in the same manner as rape-cake, and delivered 

 into the furrow with the seed. The Chinese, who 

 have more practical knowledge of the use and appli- 

 cation of manure than any other people existing, 

 mix their night-soil with one third of its weight of a 

 fat marl, make it into cakes, and dry it by exposure 

 to the sun. In this state it is free from any disagree- 

 able smell, and forms a common article of commerce 

 of the empire. After night-soil, pigeon's dung comes 

 next in order as to fertilizing power. If the pure 

 dung of cattle is to be used as manure, like the other 

 species of dung which have been mentioned, there 

 seems no reason why it should be made to ferment, 

 except in the soil; or if suffered to ferment, it should 

 be only in a very slight degree. A slight, incipient 

 fermentation is, undoubtedly, of use in the dunghills: 

 for, by means of it, a disposition is brought on, in 

 the woody fibre, to decay and dissolve, when it is 

 carried to the land, or ploughed into the soil ; and 



woody fibre is always in great excess in the refuse of 

 the farm. Too great a degree of fermentation is, 

 however, very prejudicial ; and it is better that there 

 should be no fermentation at all before the manure is 

 used, than tlrnt it should be carried too far. In cases 

 where farm-yard dung cannot be immediately applied 

 to crops, the destructive fermentation of it should be 

 prevented, very carefully, by defending the surface 

 of it, as much as possible, from the oxygen of the 

 atmosphere ; a compact marl, or a tenacious clay, 

 offers the best protection against the air ; but before 

 the dung is covered over, or, as it were, sealed up, 

 it should be dried as much as possible. If the dung 

 is found to heat at any time, it should be turned over 

 and cooled by exposure to air. When a thermometer 

 plunged into it, does not rise above 100 Fahr., there 

 is little danger of much aeriform matter flying off ; 

 if the temperature is above that point, the clung will 

 require to be immediately spread open. Also, when 

 a piece of paper, moistened in muriatic acid, held 

 over the steams arising from a dunghill, gives dense 

 white fumes, it is a certain test that the decomposi- 

 tion is going too far ; for this indicates that volatile 

 alkali is disengaged. The situation in which dung 

 is kept by farmers is often very injudicious, it fre- 

 quently being exposed to the direct influence of 

 the sun ; whereas it should always be kept under 

 sheds, or, at least, on the north side of a wall. Less 

 perishable substances, of animal origin, are some- 

 times used as manure, such as horn, hair, feathers, 

 and bones; but, owing to their dry nature, they 

 require a longer period for their decomposition. 

 They are not calculated for annual harvests, but to 

 fructify the soil for a produce of much longer dura- 

 tion, such as that of olive trees and of vineyards. 

 Vegetable manure does not undergo fermentation 

 previous to being buried in the soil. Of this kind of 

 manure, green crops, such as clover, lupins, and 

 buckwheat, which are ploughed into the soil, are the 

 best, since they contain a considerable quantity of 

 water, and, when buried, serve to lighten the soil 

 previous to decomposition. It is especially adapted 

 to hot climates. Rape-cake, which is used with great 

 success as a manure, contains a large quantity of 

 mucilage, some albuminous matter, and a small 

 quantity of oil. It should be used recent, and kept 

 as dry as possible, before it is applied. It forms an 

 excellent dressing for turnip crops, and is most eco- 

 nomically applied by being thrown into the soil at 

 the same time with the seed. Sea-weeds, consisting 

 of different species of fuci, algae, and confervas, are 

 much used as a manure, on the sea coasts. This 

 manure is more transient in its effects, and does not 

 last for more than a single crop, which is easily 

 accounted for, from the large quantity of water, or 

 the elements of water, which it contains. It decays 

 without producing heat, when exposed to the atmo- 

 sphere, and seems, as it were, to melt down, and 

 dissolve away. It should be used as fresh as it can 

 be procured, and not suffered to lie in heaps, exposed 

 to the air, for six months or a whole year, as it is 

 often allowed to do. Soot, which is principally 

 formed from the combustion of wood and pit-coal, 

 contains, likewise, substances derived from animal 

 matters, and is a very powerful manure. It re- 

 quires no preparation, but is thrown into the ground 

 with the seed. 



The foregoing species of manure have, for the 

 sake of convenience, been described separately, 

 though they are very rarely employed unmixed 

 by the farmer ; on the contrary, the most com- 

 mon manure consists of a mixture of animal, 

 vegetable, and mineral substances, such as farm- 

 yard litter, night-soil, mud from the streets, dust 

 from the roads', or earth from the bottom of ponds 





