M ANURES 55 



N in fish manure 



RS. 



10-0 



N in dried blood j *" 



P 2 5 in superphosphate 4*8 



P 2 6 in bone meal '9 



P 2 5 infish -9 



K*0 in sulphate of potash 37 



Summary, 



Potash 3*5 



P 2 5 soluble 5-0 



P 2 5 insoluble 1*0 



N in saltpetre imported 13*0 



N in saltpetre .. 6*5 



N in bones, poonacs. etc. ... ... 1V0 



These can only be taken as approximate. 



"Unit" Prices of Manures. * 



The price divided by the percentage gives the cost of a 

 "unit ", i.e., the one-hundredth of a ton. If a standard unit 

 price is adopted, the real value of any manure can be found by 

 multiplying the percentage of each ingredient by the standard 

 price and adding all together. The real value can then be 

 compared with the market price. 



It is customary in fixing the prices of manures per ton, on 

 the system of valuing by units, to allow only for the phos- 

 phates dissolved or soluble, the phosphates undissolved or 

 insoluble, the nitrogen equal to ammonia and the potash. 

 Other items are seldom taken notice of, and in the case of a 

 mineral superphosphate it is not even usual to allow for the 

 insoluble phosphate. 



The above prices are of course only approximate, as they 

 vary according to markets, and only represent the value at the 

 ports or manufactories ; the cost of bags, carriage, credit, etc., 

 must be added according to circumstances. 



It must be borne in mind that the commercial values bear 

 no relation to the manmial values ; the soluble phosphate in 

 a mineral superphosphate, for instance, being probably as 

 good for the plants as that in a bone superphosphate, although 

 the latter has a higher market value. The cheapest sources 

 should be tried first in experiments. 



