igo6.] 



Manurial Effect of Bone-Meal. 



739 



sown were found not only to germinate well, but the resulting 

 plants were excellent and were untouched by the beetle, whilst 

 others from untreated seed — in a neighbouring drill — lost colour 

 and showed a number of brown marks. A record of these 

 experiments will be found in this Journal (Vol. XII., April, 1905, 



Experiments which have been carried out with bone-meal 

 in comparison with other phosphatic manures have frequently 



although in many instances the reverse has been found to be 

 the case in actual practice. Professor Soderbaum, of Stock- 

 holm, has recently published the results of some experiments 

 in this connection which are of considerable interest. 



It was pointed out in 1900 by Kellner and Bottscher that 

 the experiments which gave results unfavourable to bone-meal 

 were made either on soils which were naturally strongly cal- 

 careous or on those to which carbonate of lime had been 

 added. They found, in fact, that the effect of bone-meal was 

 much less on calcareous soils, or on soils manured with lime, 

 than on unlimed soils, and that the manurial action of the phos- 

 phoric acid in bone-meal depended very largely on the lime- 

 content of the soil. After attention had been directed to this 

 point, pot experiments were carried out, which gave results 

 favourable to bone-meal, though a smaller crop was still 

 obtained than after superphosphate or basic slag of a corre- 

 sponding quality. 



This fact admitted of two explanations. On the one hand, 

 it could be assumed that the bone-meal, in consequence of its 

 slow solubility, hardly ever exercised the same phosphatic 

 action as superphosphate ; at any rate, not on plants such as 

 spring grain, with only a short growing period. On the other 

 hand, there was the possibility that besides the lime-content of 

 the soil there were other factors still unexplained which were 

 able to increase or decrease the action of the phosphoric acid 

 in bone-meal. An examination of the results of experiments 

 with bone-meal compared with other phosphates showed that 



P- 38). 



Manurial Effect 

 of Bone-Meal. 



shown that the action of the phosphoric 

 acid in bone-meal is as a rule less than it 

 is when in the form of superphosphate, 



N N N 2 



