MANURES. 285 



conditions seem so entirely those, the object of which it is to realize 

 by paring and burning, that in order to make the operation favorable 

 to the soil which undergoes it, the vegetable matter which it has 

 produced, must of necessity be transformed into black ashes ; when 

 it goes beyond this, as Mr. Hoblyn has well observed, when the in- 

 cineration is complete, and the residue presents itself as a red ash, 

 the soil may be struck with perfect barrenness for the future. The 

 burning, therefore, that was not properly managed, that led to the 

 complete incineration of all the organic matter, would, for the same 

 reason, have a very bad effect in the preparation of the Picardy ash- 

 es ; which might indeed act in the same way as turf ashes from the 

 hearth and oven, but which, deprived of all azotized principles, would 

 not ameliorate the ground in the manner of organic manures. 



I have frequently seen the process of burning pertormed in the 

 steppes of southern America. Fire is set to the pastures after the 

 grass which covers them has become dry and woody ; the flame 

 spreads with inconceivable rapidity, and to immense distances. The 

 earth becomes charred and black ; the combustion of those parts 

 that are nearest to the surface, however, is never complete ; and a 

 few days after the passage of the flame, a fresh and vigorous vege- 

 tation is seen sprouting through the blackened soil, so that in a few 

 weeks the scene of the desolation by fire, becomes changed into a 

 rich and verdant meadow. 



ANIMAL EXCREMENTS. 



Horse-dung. The composition of horse-dung would lead us to 

 infer that its action must be more energetic than that of cow-dung. 

 Nevertheless, agriculturists frequently consider it as of inferior qual- 

 ity. This opinion is, even to a certain extent, well founded. Thus 

 although it be acknowledged that horse-dung covered in before it has 

 fermented, yields a very powerful manure, it is known that in general 

 the same substance, after its decomposition, affords a manure that is 

 really less useful than that of the cow-house. This comes entirely 

 from the fact that the droppings of the stable, by reason of the small 

 quantity of moisture they contain, present greater difficulties in the 

 way of proper treatment than those from the cow-house. Mixed 

 with litter and thrown loosely upon the dung-hill, horse-dung heats 

 rapidly, dries, and perishes : unless the mass be supplied with a suf- 

 ficient quantity of water to keep down the fermentation, and the 

 access of the air be prevented by proper treading, there is always, 

 without the least doubt, a considerable loss of principles, which it is 

 of the highest importance to preserve. I can give a striking instance 

 of this fact in the changes that happen in the conversion of horse- 

 dung into manure in the last stage of decomposition : fresh horse- 

 dung in the dry state contains 2.7 per cent, of azote. The same 

 dung laid in a thick stratum and left to undergo entire decomposition, 

 gave a humus or mould, from which, reduced to dryness, no more 

 than one per cent, of azote was obtained. I add, that by this fermen- 

 |ation or decomposition, the dung had lost nine tenths of its weigtt 



