11 



Mixing Efficiency Table. 



The above table shows that in most instances allowances are made for a 

 suitable margin of overruns. As might be expected, however, these are kept 

 as low as is consistent with making the mixtures conform to the guarantee. 

 Of the 32 manufacturers, — 



22 showed an overrun in all of the elements guaranteed. 



24 showed an overrun and 8 a shortage in nitrogen. 



31 showed an overrun and 1 a shortage in available phosphoric acid. 



31 showed an overrun and 1 a shortage in potash. 



On the whole, the guarantees of available phosphoric acid and potash were 

 much better maintained than the guarantees of nitrogen. In most instances 

 the nitrogen deficiencies have been very small, perhaps indicating too great 

 a zeal on the part of the management to avoid costly overruns. 



Nitrogen in Mixed Fertilizers. 



The following table has been prepared to show the average proportion 

 and quality of the different forms of nitrogen found in mixed commercial fer- 

 tilizers sold in Massachusetts during 1924. The fertilizers are divided into 

 seven groups according to the ammonia guarantee. 



