own use. Many of these, therefore, will not appear among- 

 the licensed goods but have been listed as farmers' samples. All 

 samples have been taken strictly in accordance with our fertilizer law 

 requirements. Whenever possible the same brand has been taken in 

 various parts of the state and a composite sample, composed of equal 

 weights of the various samples, has been used for analysis. It is- 

 believed that this gives a better representation of the brands than 

 can the analysis of one sample. 



An effort is made to sample every brand licensed. During the 

 season samples were taken from about i8o agents. The 

 towns visited by our collector vary somewhat from those of the pre- 

 vious season — they comprise about 90 in number and represent 

 every county in the state. Ninety-six more samples have been 

 collected and analyzed than during the preceding year. At our 

 request representative samples were sometimes forwarded of those- 

 brands not found in our general markets. Such samples are 

 designated in the tables of analyses as manufacturers' samples. 



All commercial fertilizers are bought for the purpose- 

 Essential of supplying nitrogen, potash, phosphoric acid and 

 Constituents sometimes lime, to growing plants in suitable and 

 of Fertilizers, available forms; the other eight elements, hydrogen,, 

 oxygen, carbon, iron, magnesium, sulphur, chlorine, 

 and calcium or lime, usually regarded as being essential to the 

 proper growth and production of plants, are in most cases abundantly 

 supplied either from the air or soil. It was formerly believed by 

 investigators that sodium, silica, and manganese which are usually 

 found in the plant ash, were essential to the proper growth of plants ;. 

 more recent investigations, however, have disproved this fact. The 

 commercial as well as the agricultural value of a fertilizer, therefore, 

 depends primarily upon the quantity as well as the quality of the 

 three essential elements of plant food which it contains. 



In considering briefly the various forms and functions of 

 Nitrogen, the first three elements mentioned, we find that nitrogen 



in its natural state is a gas, and that it comprises about 

 four-fifths of our atmosphere. There is only one class of 

 agricultural plants, however, which has the power of acquiring free 

 atmospheric nitrogen, namely legumes such as clover, alfalfa, peas, 

 beans, etc.; they do this by means of nodules which develop on- 



