EXPERIMENT STATION BULLETINS. 197 



INSPECTION OF COMMERCIAL FERTILIZERS. 



By R. C. Kedzie. Bulletin No. 64, Chemical Department. 



The law in this state requires the analysis every year of all commercial 

 fertilizers sold or offered for sale, the retail price of which exceeds ten 

 dollars per ton, and the publication of the results of analysis. The mater- 

 ials to be determined in such analysis are "nitrogen in available form, 

 potash soluble in water, phosphoric acid in available form, and the insol- 

 uble phosphoric acid." The chemists of Europe and America have selected 

 these same materials as determining the chief value of commercial fertil- 

 izers, and in every state of our Union where the law prescribes chemical 

 analysis of commercial manures as one condition of sale, these are the 

 materials to be determined as the basis of value. 



These are not the only materials concerned in raising crops, but they 

 are the only materials for ivhich the farmer can afford to pay more than 

 ten dollars per ton. These substances are all contained in stable manure, 

 but such stable manure is not sold in the open market for more than ten 

 dollars per ton, nor could the farmer afford to pay such price for this manure, 

 and therefore no analysis of such manure is required by law. There are 

 other materials required for the growth of crops, such as lime, magnesia, 

 oxide of iron, sulphates, etc., but these are constituents of all good soils, 

 and if required in excess of what is in the soil, can be bought for much 

 less than ten to twenty dollars per ton. A man who buys at twenty dollars 

 per ton what can be bought for three dollars per ton is not wisely investing 

 his money. Plaster and salt are very cheap in this state and need not be 

 purchased at inflated prices. Lime and the silicate of lime, alumina and 

 silicate of alumina, magnesia, and oxide of iron, make up the great bulk of 

 the soils of Michigan, and the farmer does not need to buy his soil mater- 

 ials at twenty dollars per ton. Land is bought and sold by the acre, not by 

 the ton. An acre of land, taken to the depth of one foot, weighs about 

 2,000 tons. To buy the chief materials of our soil, even at the rate of 

 ten dollars per ton, would be buying soil at the rate of $20,000 per acre, 

 which is too high a price for even Michigan lands. Because silica, lime, 

 magnesia, and oxide of iron are found in all agricultural plants, and many 

 of these are essential for the growth of plants, it does not follow that we 

 shall profitably purchase these materials for manures at inflated prices, 

 when we find that all arable soils contain these substances by hundreds of 

 tons. 



The case is different with materials that are found in very small amount 

 in the soluble or available form in the soil, and which are soonest exhausted 

 by cropping, such as available nitrogen, potash soluble in water, and phos- 

 phoric acid. Under certain conditions the farmer may find a profit in 

 buying and using commercial manures containing these substances, even 

 at prices demanded for commercial fertilizers, but it does not follow that 

 he may with equal wisdom buy all the other materials contributing to 

 plant growth and at the same high prices, while they are found in abund- 



