The Conservation of Farm-yard Manure. 
831 
enjoyment of charlatans. . . . Agriculture in general, and French 
agriculture in particular, has made immense progress in the last 
century, progress which has been accomplished almost wholly with 
dung as a fertiliser. The production of wheat in France in 1789 
was not more than 31,000,000 hectolitres, while now, in a medium 
season her soil grows three times as much, and four times as much 
in a good one.” 
The manure annually produced on the farms of France repre- 
sents, in nitrogen, phosphates, and potash, a value which M. Grandeau 
calculates at nearly 1,650,000,000 francs. In English money this 
represents a sum of 66,000,000^. sterling, and it is interesting to 
see how the author arrives at it. He starts with the last decennial 
“Agricultural Returns” of France, which show, for all live stock, 
a total live-weight of nearly 6j- million tonnes, which may for con- 
venience’ sake be directly taken by the English reader as “ tons ” — 
the difference between the English ton and the French tonne of 
1,000 kilog. being comparatively small. The official calculations, 
given in these returns, put the manure produced by these 6,250,000 
tons of live stock at 84,000,000 tons, but this estimate M. Grandeau 
considers to be too low. He discusses the experimentally ascer- 
tained yield of manure per ton of live weight from horses, mules, 
asses, horned stock, sheep, and pigs, quoting, among other autho- 
rities, M. E. Lecouteux and M. A. Girardin, who concur, from ex- 
perimental evidence, in putting the annual production of dung per 
ton of live weight — taking a fair average of all animals of various 
ages — at some 25 tons of fresh manure (excreta and litter com- 
bined) ; or, say, 19 tons after resting for an average duration of 
time in the dung-heap. Applying the separate “ coefficients ” for 
calculating manure production from live weight in the different 
classes of animals enumerated in the French Goverment Statistics 
of 1882, it would appear that the quantity of fresh dung produced 
should be 165,000,000 tons. The average figures adopted by 
MM. Lecouteux and Girardin give an estimate of 156,000,000 tons. 
Even adopting this lower figure, we get nearly 119,000,000 tons of 
half-rotten dung. The estimates of the local commissions, there- 
fore, are, he argues, too low. It must be pointed out here, how- 
ever, that M. Grandeau appears to assume that all live stock con- 
sume litter, which forms the bulk of “ dung,” leaving out of sight 
the existence of animals that spend half or all of their lives in the 
field. Possibly this may throw some light on the difference between 
the 165,000,000 tons of fresh or 119,000,000 tons of half-rotten 
dung estimated by M. Grandeau, and the much less quantity of 
84,000,000 tons estimated in the reports of the local commissions 
as representing the dung production of France. 
In arriving at his estimate of the money value of what may 
well be called “this enormous mass of dung,” M. Grandeau adopts 
an average figure of rather more than 10 francs (say 8s.) a ton — 
a figure which in this country, at all events, we should probably 
consider too high. It is, in fact, based on the assumption that the 
nitrogen contained in the dung is worth 1*50 f. per kilog., or lather 
