MANURES. 



159 



Ordinary night-soil does not contain so large 

 a proportion of fertilizing matters as fresh excre- 

 ment, being mixed with water, ashes, soil, and 

 other rubbish. It should be deodorized before 

 it is employed in the garden by mixing it with 

 charcoal dust, gypsum, dry earth, sifted ashes, 

 and quicklime. 



Night-soil forms an excellent manure for Tur- 

 nips, the Cabbage tribe, and Celery, and indeed 

 for many other crops, though it is not so much 

 employed as it deserves to be, perhaps on 

 account of its being erroneously supposed to 

 affect the flavour of the plants. In Belgium, 

 France, and many other continental countries, 

 night-soil is highly valued as a manure. 



Pouclrette. — In some of the large towns of 

 France, Germany, and America, night-soil is 

 dried and made into a transportable form, and 

 sold under the name of "poudrette"; but as 

 it is prepared by adding largely such materials 

 as gypsum, ashes, earth, peat, saw-dust, &c, the 

 mixture forms but a poor fertilizer, and is rarely 

 worth the price asked for it. 



Sewage Manure. — Many processes have been 

 devised for the treatment of sewage from large 

 towns, so as to collect its manurial constituents 

 into a portable and saleable form. Dr. A. B. 

 Griffiths says none of these methods is alto- 

 gether satisfactory, although what is known as 

 the ABC process is considered by some to be 

 "a hit" in the right direction. The ABC 

 process consists in precipitating the manurial 

 constituents by the addition of clay, alum, blood, 

 charcoal, &c, to the sewage. The precipitate 

 so obtained, after drying, constitutes a manure 

 sold under the name of " native guano ". The 

 very best sewage manures are rarely worth 

 more than £2 per ton. 



Guano. — The word guano, derived from the 

 Spanish word huana (dung), is a term applied 

 commercially to all faecal deposits of birds and 

 marine animals which on different parts of the 

 earth's surface have been collected together in 

 greater or less purity. The quality and value 

 of these manures depend almost wholly upon the 

 amount of decomposition to which they have 

 been subjected by the action of the atmosphere. 

 The faecal matter of these animals consists essen- 

 tially of nitrogenous and phosphatic compounds. 

 The ammoniacal portion of these deposits, with 

 some of the phosphaces, are, through the long- 

 continued action of rain and air, made tolerably 

 soluble in water, and are readily washed away. 

 The phosphates of lime and magnesia are less 

 soluble. In dry climates, where very little rain 

 falls, as in some parts of Bolivia and Peru, on 



the western coast of South America, the dung 

 deposited suffers very little from the action of 

 the atmosphere, and retains nearly the whole of 

 its soluble fertilizing compounds. Guanos found 

 in the regions where much rain falls lose a great 

 portion of their soluble ingredients. The resi- 

 due is, however, often left rich in phosphates of 

 lime and magnesia. Many guanos are also much 

 deteriorated by large quantities of sand being 

 driven on to the deposits by the action of the 

 winds. The composition of the present Peruvian 

 guano is greatly inferior to that of twenty years 

 ago. Average samples contain from 5 to 8 per 

 cent of nitrogen, and from 20 to 35 per cent 

 of phosphate of lime. 



The guanos of commerce may be classified 

 under two heads: — (1) Nitrogenous guano, of 

 which Peruvian is a type; (2) Phosphatic guano, 

 of which the Bolivian is an example. 



Bats' or Texas Guano. — This manure is im- 

 ported from Texas, where it accumulates in con- 

 sideral quantities in caves frequented by large 

 numbers of bats, of which it is the dried excre- 

 ment. A microscopic examination shows the 

 remains of their insect diet. According to Dr. 

 Voelcker's analysis, bats' guano contains nitrogen 

 in three separate forms — as organic matter, as 

 ammonia salts, and in the form of nitrates. 

 Hence the nitrogen is in different degrees of 

 solubility. The nitrates are ready for imme- 

 diate absorption by the roots of plants. The 

 ammonia salts may first of all undergo a change, 

 with the ultimate formation of nitrates; and, 

 lastly, the organic matter requires time for its 

 decomposition; therefore it forms a reserve or 

 latent supply of nitrogen, which becomes active 

 after a time. 



Dr. Voelcker gives the following as the com- 

 position of good-quality bats' guano : — 



Water (loss at 212°), 



2010 



(1) Organic matter and combined water, 



50-13 



(2) Phosphoric acid, 



6-37 



Lime, 



12-19 



Iron oxide, alumina and alkali salt, ... 



S-5S 



Insoluble silica, 



2 63 



100-00 



(1) Total nitrogen (including 2'5Q nitric nitrogen), S-45 

 Equal to ammonia, ... ... ... ... 10 - 26 



(2) Tribasic phosphate, 1 3 -90 



Guano should always be mixed with six or 

 eight times its weight of fine earth or loam, or 

 with ashes or charcoal dust, or with charred 

 peat, previous to being applied to the soil. 

 Mixed in this way it may be used at the rate 

 of 4 or 5 cwts. per acre. 



Guano is also employed with great advantage 



