MICHIGAN EXPERIMENT STATION BULLETINS. 135 



INSPECTION OF COMMERCIAL FERTILIZERS. 



BY R. C. KEDZIE. 

 Bulletin No. 86, July, 1892. 



The law providing for the inspection of commercial fertilizers and regu- 

 lating their sale was enacted in 1885. The law was designed to protect 

 farmers from loss by the purchase of inferior or even worthless fertilizers 

 ofiPered for sale in our state. Other states requiring an inspection of fer- 

 tilizers before they are offered for sale, a manufacturer who had inferior 

 fertilizers for- sale might find it profitable to offer such goods in states 

 where no inspection is made, and farmers are not warned of the low grade 

 of goods offered for sale.. But for our inspection law this state might be 

 made the dumping ground for worthless fertilizers. Farmers should make 

 use of the information offered them by this law, and know what they buy 

 and be able to judge of its commercial value. 



The three most valuable materials in commercial manures are potash, 

 phosphoric acid, and available nitrogen. Each of these has a commercial 

 value, and the worth of any given quantity in the market may be stated in 

 dollars and cents. Only these three substances are considered in the 

 inspection of commercial fertilizers, because the other materials are of too 

 little value to be purchased at high prices. The essential value of these 

 fertilizers lies in the potash, phosphoric acid, and available nitrogen they 

 contain. The law does not prescribe the amount of these substances in 

 any fertilizer, but requires the manufacturer or dealer to certify the com- 

 position of the fertilizer, and to deposit a sample of the fertilizer with the 

 Secretary of the State Board of Agriculture. In this way the composition 

 of the fertilizer as claimed by the manufacturer is offered to the public. 

 Samples of the fertilizer are gathered in the open market, and analyzed, 

 and the results directly compared with the claims of the manufacturer in 

 the bulletin. The farmer can thus find in the bulletin, on lines opposite 

 each fertilizer, the amount of nitrogen, phosphoric acid, and potash as 

 claimed by the manufacturer, and as actually found by analysis at this 

 laboratory. If the analysis shows more of any given substance than is 

 claimed, the goods are better than claimed; but if much less is found on 

 analysis than is claimed, then the goods are proportionately of less value 

 to the farmer. For example, an Ohio potato fertilizer was sold in the 

 state last year that fell short of the claimed amount of available nitrogen 

 by more than two per cent., and of potash by more than three per cent., 

 and the fertilizer was not worth so much as claimed by $11 a ton. By 

 consulting the tables in the bulletin, the market value of these commercial 

 fertilizers can be estimated on the basis that available phosphoric acid is 

 worth eight cents a pound, insoluble phosphoric acid three cents, potash 

 six cents, and ammonia eighteen cents. As there are 20 times 100 pounds 

 in a ton, if we multiply the value of a pound by 20, we get the value of 

 one per cent, of each substance, and thus obtain a factor for obtaining the 

 value of the material in a ton from the percentage given in the tables of 

 the bulletin. One per cent, means 20 pounds in a ton, and if the material 

 is worth eight cents a pound then each per cent, ecpals $1.60 a ton. 



