done. The large amount used adds greatly to the accuracy of th<> 

 results. Having found the parts per million of these ingredients in 

 the soil, and having the dry weight of the original sample, which 

 was taken over a definite area, it is a very simple matter to calcu- 

 late to pounds per acre for the depth to which the sample was taken. 



It is believed that this method will give the amount of plant food 

 which is in condition to be taken up by the oat plant, provided there 

 is a suitable balance in such plant food. It is the result of experience 

 in a large number of analyses. The calculation in pounds per acre 

 in this work is on the assumption that plant food does not exist to a 

 greater depth than 18 inches. 



It is desired that those who wish to cooperate in the work will 

 notify this Bureau as soon as possible, as arrangements should be 

 made without delay. 



C. C. MOORE, 



In Charge of Soil Analysis Laboratory. 

 Approved : 



JAMES WILSON, 



Secretary. 



WASHINGTON, D. C., January 3, W02. 



O 



