28 FERTILISERS AS AN AID TO 



Commercial Valuations do not indicate 

 Agricultural Value 



The one is determined by the law of supply 

 and demand, the other by soil, crop, and climatic 

 conditions. Take, for example, the 

 Valuation of mos ^ ac tive nitrogenous fertilisers, 

 nitrate of soda and sulphate of am- 

 monia ; one would suppose that the unit price 

 would be higher than in the slower acting forms 

 of organic nitrogen, such as dried blood, whereas 

 the contrary is actually the case. This is the 

 result of years of practical experience by which 

 farmers all over the world have realised its 

 greater agricultural value, and are prepared to 

 pay higher prices, so as to obtain the limited sup- 

 plies available. The unit of nitrogen in sulphate 

 of ammonia is generally the lowest in price, 

 that in nitrate of soda costing somewhat more, 

 whilst organic nitrogen in good available forms 

 is still more costly. It is thus ob- 

 vious how very unreasonable it is to 

 base the valuation of fertilisers, so 

 far as nitrogen is concerned, on the cost of its 

 lowest source. To be correct, an average must 

 be taken, and a difficulty lies in the constant and 

 sometimes considerable fluctuations which occur 

 in the cost of nitrogenous materials. This does 

 not apply, however, with so much force in the 

 case of phosphates and potash. 



The intelligent farmer buys fertiliser in order 

 to obtain available plant food, not a large bulk 

 of material irrespective of the amount and 



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