12 MANUKES. 



manure heaps exposed to the weather, is not so much due to the 

 volatilization of ammonia as to the removal of ammoniacal salts, 

 soluble nitrogenized organic matters, and valuable mineral matters, 

 by the rain which falls in the period during which the manure is 

 kept. 



20. If rain is excluded from dung heaps, or little rain falls at a 

 time, the loss in ammonia is trifling, and no saline matters of 

 course are removed ; but if much rain falls, especially if it descends 

 in heavy showers upon the dung heaps, a serious loss in ammonia, 

 soluble organic matters, phosphate of lime, and salts of potash is 

 incurred, and the manure becomes rapidly deteriorated in value, 

 whilst at the same time it is diminished in weight. 



21. Well-rotten dung is more readily affected by the deteriorat- 

 ing influence of rain, than fresh manure. 



22. Practically speaking, all the essentially valuable manuring 

 constituents are preserved, by farmj'ard manure under cover. 



23. If the animals have been supplied with plenty of litter, fresh 

 dung contains an insufiScient quantity of water to induce an active 

 fermentation. In this case fresh dung cannot be properly ferment- 

 ed under cover, except water or liquid manure is pumped over the 

 heap from time to time. 



Where much straw is used in the manufacture of dung, and no 

 provision is made to suppl}'^ the manure in the pit at any time with 

 the requisite amount of moisture, it may not be advisable to put up 

 a roof over the dung-pit. On the other hand, on farms where there 

 is a deficiency of straw, so that the moisture of the excrements of 

 our domestic animals is barely absorbed by the litter, the advan- 

 tage of erecting a roof over the dung pit will be found very great. 



24. The worst method of making manure is to produce it by ani- 

 mals kept in open yards, since a large proportion of valuable fer- 

 tilizing matters is wasted in a short time ; and after a lapse of 

 twelve months, at least two-thirds of the substance of the manure 

 is wasted, and only one-third, inferior in quality to an equal weight 

 of fresh dung, is left behind. 



