570 



of kainit contain about 2J cwt. of potash — he will need, therefore, 

 4 cwt. of kainit costing about 12s. Thus he can obtain standard 

 manures of equal agricultural value to that offered for £7 10s. 4d. 

 Put in another way the equivalents are : for every 1 per cent, of 

 nitrogen offered, 1 cwt. of sulphate of ammonia ; for every 1 per 

 cent, soluble phosphates, | cwt. of superphosphate ; for every 

 1 per cent, of insoluble phosphate, ^ cwt. of steamed bone flour; 

 and for every 1 per cent, of potash, If cwt. of kainit. 



The above is a rough method only. A more accurate method 

 is to find the unit values (i.e., the value of 1 per cent, per ton, 

 or 22.4 Ib.^ of nitrogen, soluble phosphates, insoluble phosphates 

 and potash in standard manures {e.g., sulphate of ammonia, 

 superphosphate, steamed bone flour and kainit as above) multiply 

 by the percentages of each in the compound manure and add the 

 results, adding an allowance for cost of mixing. Taking as 

 above, sulphate of am.monia (20 per cent, nitrogen) at £16 per 

 ton, superphosphate (32 per cent, soluble phosphates) at £4 10s. 

 per ton, steamed bone flour (60 per cent, total phosphates) at 

 £S per ton, and kainit (12 J per cent, potash) at £3 per ton, then 

 the unit values are : nitrogen 16s. ; soluble phosphate 2s. lOd. ; 

 insoluble phosphate 2s. 8d. ; and potash 4s. lOd. A ton of a 

 compound manure containing 5 per cent, of nitrogen, 15 per 

 cent, of soluble phosphates, 5 per cent, of insoluble phosphates, 

 and 2} per cent, of potash, would be worth, therefore, 5 x 16s. 

 plus 15 X 2s. lOd. plus 5 x 2s. 8d. plus 2 J x 4s. lOd. = 

 £7 7s. lid. per ton plus an allowance as explained above for 

 mixing. 



In working out unit prices in this way care must be taken to 

 observe whether the prices on which calculations are based are 

 prices delivered at the farm or nearest railway station, or prices 

 at the works ; if the latter, carriage of course must be added. The 

 quantities (e.g., 2 ton lots) to which the prices relate should also 

 be noted, relatively more per unit will have to be paid for small 

 than for large quantities. 



The unit method of valuation also allows of the prices of 

 standard manures being compared with one another. A full 

 account of the method will be found in the Ministry's Leaflets 

 Nos. 72 and 80. Unit values at London are regularly published 

 in the Ministry's Agricultural Market Report fprice 2d.) each 

 week. 



