^Feb.,i9o8.] Artificial Manures Acts. 103 



Practical Utility of the Unit Value System. 



The practical utility of the unit value system is that it enables a 

 farmer to readily ascertain if the price asked for a manure is its reason- 

 able commercial value. The term used the " commercial value " must 

 not be confused with the '" agricultural value" of a; manure. They are 

 quite distinct. The commercial value represents the value of a manure 

 according to its composition. The agricultural value of a manure is 

 measured by the extent of the increase in quantity and quality produced 

 by it in a particular crop grown in a particular soil, under certain condi- 

 tions. The agricultural value of a manure may vary quite extensivelv. 

 A particular soil, for instance, may not give an increased crop return after 

 application of nitrogenous manures commensurate with the cost of the 

 fertilizer. On another soil an application of superphosphate may not 

 increase the yield. In both instances the manures would have no positive 

 agricultural value. 



The " commercial value '"' of a manure is determined by the percentage 

 of certain constituents in it possessing fertilizing properties and their 

 unit value. The assumption is made that the manures are all prepared 

 from materials of the same quality and value, but this is not strictly in 

 accord with practice as each manufacturer has his own source of supply 

 of materials. In the table of unit values it will be seen that the value 

 for citrate soluble phosphoric acid is quoted as pd. less per unit than the 

 water soluble. The general result of Victorian experiments shows that 

 water soluble phosphoric acid has a higher agricultural value in wheat 

 growing than citrate soluble phosphoric acid, and it is generally assumed 

 that its solubility enables it to come more easily within range of plant 

 roots. In any case, after application to the soil, the water soluble 

 phosphoric acid becomes "reverted." The rate at which this change 

 proceeds depends on the composition of the soil to which the fertilizer is 

 applied, the reversion teing most rapid in soils containing carbonate of 

 lime. 



Requirements of Artificial Manures Acts. 



A special feature of the Victorian Artificial Manures Acts is the re- 

 quirement of a label or tag attached to the bags declaring the guaranteed 

 •composition by analysis of any manure sold in the State in quantities 

 exceeding 56 lbs. at one sale. This is provided by section 7 of the 

 principal Act, and, as a further measure of protection to farmers, it is 

 made compulsory, under section 5, for vendors to deliver to all pur- 

 chasers of manures an invoice certificate declaring the guaranteed analysis 

 •of the manure sold. No farmer in Victoria should take delivery of 

 manure unless the above conditions of sale are complied with. Substantial 

 assistance would be rendered in the enforcement of the Act if farmers 

 Avould immediately report any irregularity obseryed in the sale of manures 

 to the Chemist for Agriculture. Additional control of the sale of manures 

 has been provided by the amended Act, loth October, 1905. Under 

 section 4, sub-section (i), officers of the Chemist's branch may collect 

 samples of manures at railway stations and farms throughout the State. 

 The results of the analysis as to the percentage of fertilizing constituents 

 found in a manure, and the percentage claimed bv the guarantee on tag 

 and invoice certificate are published side by side along with the calculated 

 value. These analyses are published in the Government Gazette and in 



