The Purchase of Artificial Manures. 



basis, should be i8-| x ris.— £io 3s. 6d., while that of the 

 latter should be 16 x ns.=^"8 16s. Comparing these figures 

 with the price actually demanded, we are able at once to 

 determine which of three lots of manure is the cheapest. 



It may be mentioned that it would be rather exceptional 

 to have the opportunity of obtaining sulphate of ammonia 

 so poor in nitrogen as 16-18 per cent., but dirty samples do 

 sometimes occur, and if the quotation of a price, to include 

 carriage, can be obtained, one can sometimes secure good 

 value in a low-class manure, provided the impurities are of 

 a perfectly harmless character. 



The value of a unit of nitrogen in nitrate of soda is 

 generally rather higher than it is in sulphate of ammonia, 

 which means that farmers regard the former source of 

 nitrogen as rather the more valuable. 



When sulphate of ammonia is selling at about £11 per ton, 

 carriage paid, nitrate of soda will usually be costing about 

 £g. On a basis of 15 J per cent, of nitrogen the value of a 



unit in the latter case works out at 1 is. gd., that is gd. 



i5'5 



higher than in the case of sulphate of ammonia. If we use this 

 unit to value sulphate of ammonia we should get the value of a 

 ton as 20 x ns. od. == £11 15s., which is 15s. higher than this 

 manure can usually be bought for when nitrate of soda is at 

 £g per ton. Now, it lies in the power of- many farmers to 

 secure this 15s. by depending on sulphate of ammonia rather 

 than nitrate of soda where the conditions are specially 

 suitable for the use of the former substance. When sulphate 

 of ammonia costs more, per unit of nitrogen, than nitrate of 

 soda, as occasionally happens, the latter manure is almost 

 invariably to be preferred. 



As a rule organic nitrogenous manures are priced in the 

 market at a much higher rate per unit than in the case with 

 the two manures just looked at. The results of their use do 

 not justify this position, for organic nitrogen will not produce 

 so much increase as nitrogen from nitrate of soda or sulphate 

 of ammonia. If we employ us. gd. as the value of a unit of 

 nitrogen in its most effective form, and apply it to the 

 valuation of some organic manures, we should get some 

 such results as these : — 



