, 



and just after sealing, and this weight is added to the weight wlie'n 

 they were first planted, which is taken as the optimum condition. At 

 intervals of two or three days during the growth of the plants the bas- 

 kets are again weighed and the weights recorded, and after each 

 weighing enough water is added to bring the weight slightly above the 

 optimum. 



At the end of fifteen or twenty days the plants are cut, weighed, and 

 the weight of each set compared with the weight of the set which 

 received no fertilizer. From the comparisons of these green weights 

 and the comparative transpiration of the plants, as shown by the loss 

 in weight, an estimate of the comparative value of the fertilizer may 

 be made. 



In the greenhouse work as carried on by the Bureau of Soils, five 

 baskets are used for each treatment and the total transpiration and 

 green weight for the five taken, thus to a large extent eliminating any 

 error which might arise from accident or inherent differences in the 

 individual seedlings were a fewer number of baskets used in the tests. 



To those desiring to use the wire-basket method and having the 

 necessary apparatus, the plan followed by the Bureau of making up 

 stock solutions is recommended. It should be remembered, however, 

 that where commercial fertilizers in which certain parts are not readily 

 soluble are used the solution should be thoroughly shaken before tak- 

 ing out the portion necessary for a treatment. In case no apparatus 

 is available for making the measurements necessary in mixing the 

 stock solutions, the following plan may be used and results of some 

 value obtained, although not so reliable as those obtained by more 

 accurate methods: 



To 124 ounces, or 7f pounds, of dry, well-pulverized soil add 1 ounce 

 of the desired fertilizer. Mix very thoroughly and pass through a 

 sieve at least twice. To 79 ounces, or nearly 5 pounds more of soil, 

 add 1 ounce of the mixture formed above and mix in the same way. 

 This new mixture contains fertilizer at the rate of 200 pounds per acre. 

 When larger applications are desired, proportionally larger quantities 

 of the first mixture should be taken. Obviously these mixtures should 

 be repeated as many times as there are fertilizers to test, after which 

 the samples of fertilized soil are treated exactly as described in preced- 

 ing paragraphs. Lime, manure, and cowpea vines, being used in 

 larger quantities than the commercial fertilizer, require a smaller 

 amount of soil in the first mixture in order that 1 ounce may be uni- 

 formly required for all treatments. For this purpose 11, 4, and 1J 

 ounces of soil will be required in the first mixture for 1 ounce of lime, 

 cowpea vines, and manure, respectively. One ounce of these mix- 

 tures added to 79 ounces, or nearly 5 pounds of soil, will furnish these 

 ingredients at the rate of 2,000, 5,000, and 10,000 pounds per acre, 

 respectively. If the 5-pound samples are more than sufficient to fill 



