MAJSrUEING IN THEOEY AND PEACTICE. 



169 



Any manure which, restores all the suhstanoes 

 taken from the soil by the growth of plants is a 

 "general manure," of which good farmyard dung 

 is the most "perfect type" hecause it supplies not 

 merely the mineral constituents, but also the car- 

 bonaceous and nitrogenous matters necessary for 

 building up the organic structure of the plant. 

 Artificial manures, on the other hand, are fre- 

 quently supposed to be mere stimulants ; and the 

 very fact that but a small quantity of them may 

 produce — as we have already seen — as much or more 

 increase of crop than a very large application of 

 farmyard dung, is sometimes brought as an argu- 

 ment against the use of artificial manures. 



Farmyard Manure is a mixture of the solid 

 and liquid excrements of animals, together with the 

 straw or other materials used as litter. 



The composition will naturally depend upon the 

 character of the animals contributing to it, the 

 quality of their food, and the nature and proportion 

 of the litter. 



The following table by Boussingault gives an 

 analysis of the quantity of carbon, hydrogen, nitro- 

 gen, oxygen, and ash in the excrements of the horse 

 and cow in their natural state, and after drying at a 

 temperature of 212° Fahr. 



From these results we see that, weight for weight, 

 the urine of the horse, in its natural state, contains 

 three times as much nitrogen as its dung ; that of 

 the cow twice as much ; and the difference, especially 

 in the horse, is still more conspicuous when they are 

 dry. Potash forms about nine-tenths of the ash or 

 inorganic part of the urine of the ox, while less than 

 3 per cent, of that substance is found in the solid ex- 

 crement. Phosphoric acid is not met with in the 

 urine, but forms about 10 per cent, in the composi- 

 tion of the dung. 



"We learn, therefore, that the urine of animals is 

 iar more valuable as a manure than their solid 

 excrements, yet greater care is taken to preserve the 



latter, the former being too frequently allowed to 

 run into the drains. The putrefaction of urine 

 greatly promotes the rotting or " ripening " of long 

 dung. When clean straw dung is dug into the 

 soil it decomposes only very slowly ; and hence when 

 employed as manure its constituents are not soon 

 available to plants. But when left in contact with 

 putrid urine, the straw rapidly rots, and its ingre- 

 dients 'pass from a comparatively inactive condition 

 into immediately available plant-food. 



Co-nr-dung is the most abundant and least valu- 

 able in composition of the animal manures. It 

 decomposes slowly, giving out but little heat ; hence 

 it is said to be a " cold manure." 



Horse-dung is more valuable than cow-dung. 

 It contains, as we see from the foregoing table, less 

 water, is not so coherent, and does not form, during 

 its decomposition an imctuous mass such as cow- 

 dung does. Horse dung decomposes rapidly, and is, 

 therefore, a " hot or forcing manure." It may be 

 usefully added to cow-dung, rendering the latter 

 more friable, whereby it can be more equally dis- 

 tributed throughout the soil. 



Sheep-dung decomposes more rapidly than cow- 

 dung, and not so quickly as horse-dung. It is richer 

 in soKd matters than the former. 



Pig-dung. — The pig being almost an omnivorous 

 animal, its excrements probably vary in composition 

 according to the natiire of its food more than in any 

 other animal. Its dung is soft and compact, and 

 decomposes slowly. It is one of the richest kinds of 

 animal manures ; but it is alleged that when used 

 alone as 'manure it gives a disagreeable flavour to 

 some vegetables, and on stiff soil favours insects. 



Guano is the excrement of sea-fowl, and is found 

 on rocky islets, principally on the coast of Peru, 

 where rain seldom falls. It owes its value as a 

 manure to the fact that it contains from 6 to 13 

 per cent, of ammonia, from 10 to 14 per cent, of phos- 

 phoric acid, and 7 to 13 per cent, of alkaline salts. 



Peruvian guano is considered the most valuable 

 auxiliary manure which the gardener possesses, as 

 it resembles, in, the complexity of its composition, 

 farmyard dung more than most artificial manures. 

 It may be applied at the rate of from 3 to 5 cwts. per 

 acre, but should never be so-wn -without having been 

 first sifted and any hard lumps reduced to pow- 

 der. It is also a good plan before sowing to mix the 

 sifted guano with dry soil or ashes. Care should 

 be taken that it be not brought into direct contact 

 with newly-sown seed. 



