HARDWICKE'S SCIENCE-GOSSIP. 



223 



CONCERNING MANURES. 

 By F. Barker Cooke, F.C.S., F.L.S. 



{Continued front p. 210.] 



TO supply these elements the following manures 

 are used : — 

 Farmyard manure.— This is by far the most 

 perfect manure, for it contains all the constituents 

 required by cultivated crops, as may be seen from the 

 following analysis by the late Dr. Voelker : — 



Per cent. 



Water 75"42 



*Soluble organic matter 2>'T l 



Soluble ash I '47 



Silica 0-254 



Phosphate of lime . . . *3S2 



Lime -"7 



Magnesia '047 



Potash . "446 



Soda -023 



Sodium chloride .... '037 

 Sulphuric acid .... '058 



Carbonic acid and loss . . ' 106 



•(■Insoluble organic matter 12*82 



Insoluble ash 6 "58 



Silica 2-434 



Oxides of iron and alumina -947 

 (Containing phosphates equal"! 

 to phosphate of lime) / 



Lime 1*667 



Magnesia '091 



Potash -045 



Soda -038 



Sulphuric acid .... '063 

 Carbonic acid and loss . i'295 



ioo-oo 



But farmyard manure has a further advantage 

 over all other manures, in that it physically improves 

 the land by rendering it porous and thus accessible 

 to air. It consists of the excrements of cattle, their 

 litter and the refusal of their fodder, well trodden 

 down and partly fermented, and then removed to a 

 convenient place, where it is made into a heap for 

 future use. Its composition naturally varies with the 

 kind and condition of the animals producing it, the 

 richness of their diet, the quality and quantity of 

 litter, and with its subsequent treatment. Thus, 

 fattening cattle void richer manure than lean ; older 

 than young, which retain much of the phosphates to 

 form bone and of the nitrogenous substances to form 

 muscle and blood ; and those fed on oil-cakes or 



* Containing "297 per cent of nitrogen, equal to '360 per cent, 

 of ammonia. 



•j- Containing -309 per cent|of nitrogen, equal to '375 per cent, 

 of ammonia. 



Total ammonia in the free state = -046 per cent. 

 „ „ „ form of salts = -057 „ ,, 



leguminous seeds than those on oats, hay, or 

 potatoes. The manure should be thoroughly well 

 mixed, as the solid and liquid portions differ in 

 composition, the former containing most of the 

 phosphoric acid and lime, the latter the alkaline salts 

 and nitrogenous substances. Care should, therefore, 

 be taken not to lose any of the urine, but to collect 

 all not absorbed by the straw by means of drains. 

 The yard should also be well protected from rain, 

 which would wash away many of the valuable 

 ingredients. By storing the manure in heaps and 

 covering it with mould it is kept moist and unexposed 

 to the air, which prevents the formation of mould and 

 too rapid fermentation. The organic matters are 

 decomposed, giving off carbonic acid gas, and from 

 this cause and the loss of moisture the heap grows 

 less both in bulk and weight. All the mineral 

 constituents remain, but some of the insoluble are 

 rendered soluble ; and the nitrogenous substances, 

 such as urea, are decomposed with the formation of 

 ammonium-salts. If applied in autumn, farmyard 

 manure is best ploughed in fresh, but if in spring it 

 should be well rotted so as to be at once available 

 for plant-food. If farmyard manure be not made on 

 the farm, or cannot be obtained in the immediate 

 neighbourhood, it is more economical to use arti- 

 ficial manures which contain the fertilising matters in 

 a concentrated form. 



Guano is the next important manure, as it is also of 

 complex composition and contains both mineral and 

 nitrogenous constituents. It consists chiefly of the 

 excrements of innumerable aquatic and fish-eating 

 birds, such as penguins, gannets, cormorants, etc., 

 and in some places that of seals. It was used as a 

 manure by the Peruvians in the time of the Incas, 

 under whose rule most stringent laws were enacted 

 for the protection of the birds. It occurs in extensive 

 deposits on the coasts of Peru and Bolivia and on 

 the adjacent islands ; and it was from Peru that 

 Baron von Humboldt first brought some to Europe 

 in 1804. Since then deposits of guano have been 

 found at the Ichaboe Islands and Saldanha Bay on 

 the south-west coast of Africa, the Kooria Mooria 

 Islands on the south coast of Arabia, Sombrero and 

 Navassa, uninhabited islands in the Caribbean Sea, 

 and various other places. It is only in rainless, or 

 nearly rainless, countries that nitrogenous guanos can 

 be formed, for many of their constituents are soluble in 

 water. Guanos differ very much in composition and 

 are sometimes divided into "nitrogenous-guanos," 

 such as Peruvian and Chincha Islands, and "phos- 

 phatic-guanos," in which most of the soluble and 

 nitrogenous substances have been dissolved out by 

 rain, and which are, consequently, rich in phosphate 

 of lime. Some Bolivian, Navassa, and Sombrero 

 guanos are examples of phosphatic guanos, which are 

 generally ground to fine powder and treated with 

 sulphuric acid, which decomposes the phosphate of 

 lime and forms super-phosphate. Guanos thus 



