EXPERIMENT STATION, 25 



Peruvian guano, superphosphates, fish-scraps, dried blood, potash 

 salts, plaster, etc., have a high agricultural value which is related 

 to their trade-value, and to a degree determines the latter value. 

 But the rule has many exceptions, and in particular instances the 

 trade- value cannot always be expected to fix or even to indicate 

 the agricultural value. Fertilizing effect depends largely upon 

 soil, crop and weather, and as these vary from place to place and 

 from year to year, it cannot be foretold or estimated except by 

 the results of past experience, and then only in a genei-al and 

 probable manner. 



For the above first-named purpose of valuation, the trade-values 

 of the fertilizing elements which are employed in the computations 

 should be as exact as possible, and should be frequently corrected 

 to follow the changes of the market. 



For the second-named use of valuation, frequent changes of the 

 trade-values are disadvantageous, because two fertilizers cannot 

 be compared as to their relative money-worth, when their valua- 

 tions are estimated from different data. 



Experience leads to the conclusion that the trade-values adopted 

 at the beginning of a year should be adhered to as nearly as pos- 

 sible throughout the year, notice being taken of considerable 

 changes in the market, in order that due allowance may be made 

 therefor. It should be remembered that, in an Annual Report, 

 the fluctuations in trade-value that may occur within the year 

 cannot be accurately followed, and the comparisons of estimated 

 values are mostly in retrospect. 



Analyses and Valuations of Fertilizers. 



The classification of the Fertilizers analyzed in the Station Lab- 

 oratory from January 1st to Nov. 1st, 1881, is as follows : 

 9 plain (non-nitrogenous) superphosphates. 

 44 nitrogenous ("ammoniated") superphosphates and guanos. 

 24 special fertilizers, or " formulas." 

 18 bone manures. 

 11 dried blood and tankage. 

 14 fish manures. 



1 tortoise shell saw dust. 



7 castor pomace and cotton seed meal. 



2 night soil and Pollard's night soil fertilizer. 

 11 potash salts. 



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