12 



The question is of course not settled by one harvest, for there is 

 a possibility tliat the after-effect of bone-meal phosphoric acid can 

 make up for what it has neglected to do in the first year. 



Series C. Table III. (1S94.) 



It might be thought that although with bone meal fertilization an 

 intensive and quick effect could not be produced, yet a field, by its 

 application, might be so enriched as to produce a profitable effect 

 for a long time. 



To test this question, oats and then mustard were raised in 1804, 

 on the same soils, without a new application of phosphoric acid. 

 The necessary amounts of nitrogen and potash were given. Results 

 are shown in Table III and are thus summarized : — 



1. The after-effect of the bone-meal application was as follows: 



The smallest of these applications of superphosphate did not 

 show any considerable after-effect. This can be easily understood, 

 for in the first year it was relatively all taken up by the plants. 

 IMoreover, it is known that a part of the soluble phosphoric acid in 

 the soil enters into less soluble forms. 



; The larger applications, however, showed a very satisfactory after- 

 effect, which has far exceeded that of equal quantities of phosi)ho- 

 ric acid in bone-meal. We therefore conclude : that the after-effect 

 of bone-meal phosphoric acid, in the case of oats, was not 

 greater, but very much less than that of the superphosphate, and 

 further, the bone- meals by no means made up for what they had 

 neglected to do in the first year. 



Tlie experiments in which mixtures of superphosphate and bone 

 meal were applied gave the same result, as for instance : — 



a. 1.2 grams phosphoric acid. 



Increase of yield. 

 Grams. 



As superphosphate gave 43.41 



In raw bone-meal " 13.58 



In glue-free bone-meal " 22.34 



Average yield increase due to hone-meals^ 17.96 



b. 0.6 gram of superphosphate acid with 0.6 gram of bone-meal 

 acid gave an increase of yield of 24.94 grams. The average results of 

 the experiments with raw and glue-free bone-meal are the same. 



