191S.] PUBLIC DOCUMENT — No. 31. 41a 



respiration or exhalation of carbon dioxide has been measured as 

 a guide to the rate of chemical change taking place in the fruit 

 after being picked. 



The latter group of problems was taken up at the request of 

 the Bureau of Plant Industry of the United States Department 

 of Agriculture, and will necessarily extend into next year. 



The soil problems must also continue in order to follow up 

 promising leads arising from this year's work. 



2. Fertilizer Section. 

 The work of the fertilizer section, in charge of Mr. Haskins, 

 with Messrs. Walker, Allen and Scull as assistants, may be 

 summarized as follows : — 



(a) Fertilizers registered. 

 During the season of 1917, 100 manufacturers, importers and 

 dealers have secured certificates for the sale of 512 brands of 

 fertilizer, fertilizing materials and agricultural limes. They are 

 classed as follows : — 



Complete fertilizers, 175 



Ammoniated superphosphates, 182 



Ground bone, tankage and dry ground fish, 54 



Wood ashes, 4 



Chemicals and organic nitrogen compounds, 65 



Agricultural limes, 32 



512 



(6) Fertilizers collected and analyzed. 

 During the year 5,452 tons of fertilizer were sampled, ne- 

 cessitating the sampling of 12,801 sacks. One hundred and 

 thirty-six towns were visited; 1,047 samples, representing 441 

 distinct brands, were drawn from stock found in the possession 

 of 360 different agents or owners, and 626 distinct analyses 

 were made. In addition, numerous samples of materials both 

 single and mixed were officially collected and analyzed for 

 farmers, so that the total number officially collected and ex- 

 amined was as follows: — 



