In addition to the wire baskets the apparatus necessary for the 

 more scientific work of a laboratory consists of two balances, one 

 having a minimum capacity of one-tenth gram, the other a maxi- 

 mum capacity of about 10 pounds; a graduated cylinder for measur- 

 ing liquids; several galvanized-iron pans 14 inches in diameter and 

 .2$ inches deep, and some shallow boxes or trays 20 inches long, 16 

 inches wide, and 1 or 2 inches deep to hold a group of baskets. The 

 baskets or pots are made from galvanized-wire net having one-eighth- 

 inch mesh and are of simple construction (see fig. 1 ) . The net is cut 

 into strips 3 inches wide by 10 inches long. The ends are brought 

 together and fastened by short rivets. At intervals along one end of 

 the cylinder thus formed vertical incisions one-half inch long are made 

 and the ends turned in to hold the bottom, which consists of a disk of 

 the same material. The top of the basket is then dipped into hot 

 paraffin to the depth of about 1 inch, removed, and dipped again until 

 a rim of paraffin is formed. Numbers are then attached to the pots 

 so that a record of each may be kept, and 20 pots are placed in each 

 tray. This completes the construction of the wire basket up to the 

 time of filling it with soil. 



The soil to be examined should be a composite sample made up 

 from a large number of separate samples taken from different parts 

 of the field and very thoroughly mixed together. From this com- 

 posite sample is weighed out a number of 4-pound portions and each 

 placed in a pan, the number of portions being one more than the 

 number of different treatments which it is desired to try. The soil 

 in the pans is again thoroughly pulverized and to each is added the 

 fertilizer which it is desired to test. The quantity of fertilizing ingre- 

 dient added should correspond closely to the quantity commonly used 

 in field practice. To one portion of the soil no fertilizer is added, this 

 being used as a check with which to compare the results obtained in 

 the treated soil. 



In the greenhouse it has been found most convenient to add manure 

 and lime in the dry form, finely chopped cowpea vines, either green 

 or dry, and the other fertilizers in the form of stock solutions, pre- 

 pared in such proportion that the desired quantities may be readily 

 determined. It has also been found that the most satisfactory results 

 are often obtained when the fertilizers are added to the soils severs 

 days before planting. Dry cowpea vines and undecomposed manure 

 require a certain degree of decomposition before they benefit growing 

 plants, and the time required for lime to show beneficial effects 

 depends on the nature of its principal action in the soil. It is there- 

 fore desirable to apply these ingredients two or three weeks before 

 planting. The stock solutions used by the Bureau contain 10,000 

 parts per million of each of the following salts: NaNO 3 , K,SO 4 , and 

 CaH 4 (PO 4 ) 2 , and are made by dissolving 10 grams of the salt in 1 liter 



