EXPERIMENT STATION BULLETINS. 291 



This is the law of the state on this subject, and the only duty of the 

 college authorities is to see its provisions and regulations properly carried 

 out. It was designed primarily to protect the farmers from loss by buy- 

 ing poor and even worthless fertilizers at high prices. It has driven 

 some inferior goods out of our market and saved thousands of dollars to our 

 people. It has also improved the quality of many fertilizers sent into our 

 state, and tends to keep all manufacturers up to the quality claimed for 

 their goods. Michigan is no longer the dumping ground for fertilizers of 

 so poor quality as to be unsalable in other states. 



In these analyses attention is directed exclusively to nitrogen, potash and 

 phosphoric acid in form available for the plant. These are not the only 

 materials concerned in raising crops, but they are the only manurial mater- 

 ials for which the farmer can afford to pay more than ten dollars a ton. 

 The common soil materials, lime, magnesia, silica, alumina, oxide of iron, 

 etc., make up the bulk of our soils, which the farmer cannot afford to buy 

 at twenty to thirty dollars a ton to manure his fields made up of the same 

 materials. These common soil materials aside from nitrogen, potash and 

 phosphates do not enter into consideration in making up an estimate of 

 the value of any fertilizer. 



OBJECT OF INSPECTION OF COMMERCIAL FERTILIZERS. 



The law does not prescribe any standard for the composition of a com- 

 mercial fertilizer, the manufacturer being free to make his own standard, 

 the law simply requiring that the fertilizers offered for sale shall be up to 

 the standard set up by the manufacturer. The license to sell does not 

 certify to the value of the fertilizer, but simply states that the manu- 

 facturer or dealer offers for sale a fertilizer for which a certain content of 

 nitrogen, potash and phosphoric acid is claimed, and that samples of such 

 fertilizers have been deposited with the secretary of the college with 

 affidavit regarding the composition. Analysis is then made of each of 

 chese fertilizers, gathered in the open market as far as possible, and the 

 results of such analysis published in bulletin. The claimed composition 

 and found composition are arranged in parallel lines so that the real com- 

 position can be compared at a glance with the composition claimed for it 

 by the manufacturer. In this way the buyer can see at once by this 

 bulletin whether the fertilizer is as good as it claims. 



To find the market value, calculations can be made on the basis that 

 available nitrogen is worth nineteen cents a pound, soluble or available 

 phosphoric acid eight cents, insoluble phosphoric acid two cents, and 

 potash from four and one-half to six cents, according as it is in the form 

 of chloride or sulphate. These prices are determined each year by the 

 prices of substances from which these materials are derived in the great 

 commercial centers, e. g.. New York. 



The composition is given in parts in one hundred.- To obtain the 

 number of pounds in a ton we multiply the per cent by twenty. If we 

 multiply the number of pounds in a ton by the price of each material the 

 sum will give the value of a ton of fertilizer. Take an example in a super- 

 phosphate made in this State. 



