14 



Witli the third crop the boue-meal gave not even approximately 

 the results of that with superphosphate. 



The mixture of superpiiosphate and boue-meal phosphoric acid 

 also produced as little, with a single exception, namely with the com- 

 bination of 0.() gram of phosphoric acid in superphosphate and 1 .2 

 grams iu raw bone-meal, which gave an exceptional result of 242.4 

 grams. Such a result was produced by no other combination, and 

 we must conclude that other and peculiar circumstances were here in 

 control. 



It is now clear that for sandy soils, low in phosphoric acid, neither 

 the bone-meal phosphoric acid alone nor in combination with super- 

 phosphate can produce an effect which even approaches the corre- 

 sponding effect of the superphosphate acid ; especially is this true if 

 the relative prices are considered. In most cases the effects have 

 been so low that they do not deserve consideration. 



Series D. Table IV. (1894). 



Bone-meal is generally considered a specific fertilizer for sandy, 

 or at least light soils. In 1894 numerous experiments were made 

 w'ith this material on soils whose various amounts of phosphoric acid 

 had been determined by previous experiments. These soils belong 

 chiefly to the group known as loams, but among them were several 

 sandy soils. In this way it could be ascertained whether bone-meal 

 would do better in soils in which it were required to furnish only a 

 part of the necessary phosphoric acid. Nitrogen and potnsh were 

 applied in sufficient quantities. The results are given in Table IV, 

 and are essentially the same as those of the experiments on sandy 

 soils. The three averages for increase of yield were respectively : — 



AVith Grams. With 



118.98 glue-free bone-meal 

 Superphosphate -| 45.67 raw bone-meal 



7.5.33 steamed bone-meal 



Average 79.99 5.10 



It was here of no consequence whether the soil showed a large or 

 a small amount of phosphoric acid, for in no single instance could 

 the bone-meal phosphoric acid, applied in any form, show an eflect 

 worthy of note. In most cases the increase of yield was scarcely more 

 than the limit allowed for error in such experiments. In every case 

 the superphosphate produced most satisfactory results. That this 

 could not be otherwise may be concluded from the figures showing 

 the removal of phosphoric acid, that is the phosphoric acid in the 

 increase of yield. These averages were : — 



