SMALL HOLDINGS 133 



constructed to retain it until it is removed 

 to the land. 



The value of the fertilising matter in a 

 ton of farm-yard manure of average quality — 

 estimating the ammonia at 6d. per lb., 

 the phosphoric acid at 3d., and the potash 

 at 2d. per lb. — is from 7s. 6d. to 10s. It 

 is, however, always difficult to prevent loss 

 as between the time that the manure is 

 voided by the cattle and ploughed beneath 

 the soil. 



There is also a loss of the fertilising 

 matter, owing to the conversion of a portion 

 of the nitrogenous matter in the urine into 

 carbonate of ammonium, which is a volatile 

 substance, and therefore easily lost. It was 

 estimated by Sir John Lawes and Sir Joseph 

 Gilbert that owing to the slowness of action 

 of dung, and to the losses of fertilising matter 

 which occur during its preparation as a food 

 for plants, its actual money value was not 

 more than one-half as much as that of the 

 excrement originally produced by the stock. 

 This opinion, however, was expressed on 

 the assumption that the prices for the nitro- 

 gen, phosphoric acid, and potash in the dung 

 were estimated at the same rate as in chemical 

 manures. It is thus doubly important that 



