equaling nearly 1-2500 of an acre. The method of procedure is the 

 same as that prescribed for the soil sample, namely : Drive in one peg ; 

 stretch one side of the tape and drive in the second peg; then stretch 

 the two remaining sides and drive in the third ; cut the inclosed crop 

 even with the ground, taking care to lose no grain by shattering. 

 Place the total crop in the bag which is supplied, label carefully and 

 forward to the Department, where it will be dried, weighed, ashed, 

 and analyzed, and the material and analyses distributed, the whole 

 being calculated to pounds per acre of the different parts of the crop 

 removed. 



One method for the determination of available P 2 O 5 and K 2 O, 



FIG. 2. Shaking machine for soil extraction at constant temperature. 



which this Bureau proposes, has been worked out in connection with 

 a very elaborate research. It has been printed as a contribution 

 from this Bureau in the Journal of the American Chemical Society, 

 Vol. 24, page 79, and a reprint has been prepared for distribution. 



A very simple and inexpensive form of shaking machine (fig. 2) 

 has been designed for this work, which, with the accompanying 

 flasks, will be supplied. By the use of this apparatus it is possible to 

 have a uniform agitation and temperature throughout the work. 

 The machine may be run by any motive power at hand at the speed 

 of about 40 revolutions per minute. The temperature is kept at 

 40 C. by means of a flame under the air chamber, and owing to the 



