-28 
On the Valuation of Unexhausted Manures. 
It is, however, when we come to other purchased feeding- 
stuffs, the feeding and manure-value of which is less understood, 
but in respect to which the allowance for compensation is, like 
that for linseed-cake, also based upon original cost, that we find 
very wide differences between the allowance according to the 
" customs," and according to manure-value. Thus, in the case 
of decorticated cotton-cake, which has not only the highest 
manure-value of any of the articles enumerated in the Table at 
page 11, but has also a very high manure-value in proportion to. 
the purchasing price of the food, my estimate of unexhausted 
residue, founded on manure-value, is very much higher than that 
which would be allowed by the Lincolnshire custom. In the 
case of wheat, on the other hand, which has a very low manure- 
value, both actually and relatively to purchasing price, the 
allowance founded on manure-value would be considerably less 
than half that according to the Lincolnshire custom, founded on 
original cost. 
These few examples are sufficient to show how entirely fal- 
lacious it is to assume that the manure-value of a food, whatever 
may be its composition, bears a fixed proportion to its original 
cost. It may, perhaps, be answered that my own estimates are 
erroneous ; and certainly I do not intend to claim for them infal- 
libility, but only that they are carefully made, with due regard 
to such knowledge as at present exists bearing upon the subject. 
But let us test the question in another way. Wheat is much 
used for feeding at the present time, and the purchasing price 
of feeding qualities may be taken at 9/. lO.s'. per ton. On the 
assumption that the manure-value of any feeding-stuff is one-half 
its purchasing price, that of a ton of wheat after consumption 
would be 41. lbs. Now, the manure-value of consumed food 
may be said to depend almost exclusively on the amount of 
nitrogen, phosphoric acid, and potass, contributed to the manure ; 
and the quantity of these constituents yielded by the consump- 
tion of a ton of wheat would be, in round numbers : — 
N lbs. 
Nitrogen 34 
Phosphoric acid, reckoned as phosphate of lime , .. .. 40 
Potass '. .. .. 11 
These manurial constituents could be purchased at the present 
time as follows : — 
£ s. d. 
34 lbs. nitrogen, in 220 lbs. nitrate of soda, at 14.s. per cwt. .. 1 7 G 
40 lbs. phosphate of lime (soluble), in 154 lbs. superphosphate,) a 7 p 
at 5«. 6d. per cwt J " ' 
11 lbs. potass in 22 lbs. .sulphate of jxjtass, at IGs. per cwt. .. 0 3 2 
£1 18 2 
