MANURES. 161 



portion of the rapidly-forming ammonia. Camel dung makes the 

 strongest manure of all owing to the succulent and herbaceous 

 plant-parts that the animal feeds on. 



Whatever the droppings used, they must be rotted in pits similar 

 to those used for preparing vegetable mould ; but the necessity for 

 protection from the sun is not so great here, as the droppings 

 consist of matter that has already undergone a considerable degree 

 of decomposition. Great care should, however, be taken to pre- 

 vent a too violent fermentation, to which all animal dejections are 

 particularly liable. The contents of the pits should always be kept 

 moist and turned over from time to time, and the manure will be 

 ready at the end of two years. During the rotting process, ammonia 

 and other useful gases are formed in abundance, and are apt to 

 disappear unless special precautions are taken to fix them. The 

 best plan is to sprinkle charcoal dust or finely sifted clay or gyp- 

 sum thickly over the fermenting heap each time it has been turned 

 up. 



Farmyard manure contains from six to seven times as much 

 nitrogenous matter as pure vegetable mould on an average, i. ?., 

 from 1 to 2^- per cent of its dry weight of nitrogen. Ordinary 

 arable land, according to its quality, requires, in order to be fully 

 manured, from 200 to 400 maunds of farmyard manure per acre. 



2. POUDRETTE. Poudrette is the deodorized mixture of night 

 soil with earthy matters. It is very rich in nitrogenous substan- 

 ces and phosphates, and should, therefore, never be used pure but 

 combined with vegetable mould in the proportion necessary to 

 secure from five to six per cent, of nitrogen in the mixture. Pou- 

 drette may be prepared in pits in the same manner as farmyard 

 manure ; but as the offensiveuess of the contents prevents its being 

 turned for free aeration, the night soil, with the earthy matters, 

 should be thrown into the pits in thin layers at a time. It is ready 

 for use at the end of a year. Poudrette prepared with a large ad- 

 mixture of ashes and charcoal dust is the most valuable of all. 

 When required on a large scale, it is best, from every point of 

 view, to desiccate the night soil in special furnaces. 



3. BONE DUST. Where an appreciable proportion of phosphates 

 is required, bone dust should be added to other manures, particular- 

 ly to vegetable mould or surkhi-ash, at the rate of from four to 

 ten maunds per acre. Fresh or unboiled bones are of course to 

 be preferred to boiled ones, which, nevertheless, contain more than 

 50 per cent, of phosphate of lime. 



