176 



(1) Of the nitrogen, phosphoric acid, and potash supplied in the 

 food, comparatively small amounts are assimilated and retained in the 

 animal body, the relation between the amounts of these substances 

 excreted in the urine and the solid excremeQt depending largely upon 

 the nature of the food. 



(2) The urine is much richer in nitrogen than the solid dung. It also 

 contains considerable amounts of potash but is poor in phosphoric acid, 

 which remains almost entirely in the solid excrement. The best results 

 may therefore be expected from applying the mixed solid and liquid 

 excrement. 



The figures given in the preceding pages have only approximate and 

 comparative value. They do not admit of too strict an application in 

 practice, because barnyard manure, as can be readily understood, is a 

 very variable substance. Its composition and value depend on a variety 

 of conditions, the more important of which are (1) age and kind of 

 animal, (2) quantity and quality of food (3) proportion and nature 

 of litter, and (4) method of management of the manure and the length 

 of time it is stored. Each of these factors will be discussed in detail. 



INFLUENCE OF AGE AND KIND OF ANIMAL. 



The proportions of the potash, phosphoric acid, and nitrogen of thefood 

 recovered in the manure vary considerably with the age and kind of animal. 

 Full-grown animals, neither gaining nor losing weight, excrete practically 

 all of the fertilising constituents consumed in the food. Growing animals 

 and milch cows excrete from 50 to 75 per cent, of the fertilising consti- 

 tuents of the food ; fattening or working animals from 90 to 95 per cent. 



The variations in the composition of the manure of different classes 

 of animals will be seen from the preceding tables. From these it 

 appears that classified according to strength of equal weights of the 

 normal manure produced the common farm animals stand in the follow- 

 ing order : Poultry, sheep, pigs, horses, cows This difference in valu^, 

 however, may be largely due to differences in the food commonly fed 

 to the different classes of stock, as will be explained later. 



Sheep manure contains a small amount of water and is, weight for 

 weight, the richest manure produced by any of the common farm ani- 

 mals. It is what is caled a hot manure, fermenting rapidly with the 

 development of heat. Like horse manure it is especially liable to lose 

 ammonia. 



Horse manure is very dry and is therefore difficult to thoroughly mix 

 with litter. It is a hot manure, undergoing fermentation rapidly and 

 generating a high heat on account of its loose texture. It is likely to 

 lose ammonia even more rapidly than sheep manure, and requires care- 

 ful management — in use of litter, preservatives, etc. — from the moment 

 it is voided. The composition of horse manure is more uniform than 

 that of any other farm animal, chiefly because the food of horses is 

 more uniform. The urine is especially rich. 



Pig manure is very variable in composition, due to the variable nature 

 of the food supplied to this animal, but is generally rich although contain- 

 ing a high percentage of water. It generates little heat in decomposing. 



Tht manur% of neat cattle, like that of pigs, and for the same reason, 

 Js variable in character, but is generally poorer than that of other 

 farm animals on account of its large percentage of water. It decom- 

 poses slowly and develops little heat. 



