Some Observations on Manuring with Bone-dust. 



BY 



S. UCHIYAMA. 



The observation of Kellner and Bottcher that the availability of bone 

 dust, but not that of secondary calcium phosphate, ^^ Thomas phosphate and 

 superphosphate is depressed by calcium carbonate has been repeatedly 

 confirmed and was explained by the neutralization of the soil acidity by 

 liming.-^ In order to gain some further information the action of bone 

 dust in the presence of gypsum and of magnesium sulphate respectively was 

 compared with the depressions caused by the presence of the carbonates 

 of lime, magnesia and potassa with both sand and soil cultures, 



Sand-ciilt7ire : The experiment was carried out with of barley in 

 six series, each in three pots. Each pot contained 6 kilo, pure quartz 

 sand, and received the following manures'^' : 



15.64 g. bone dust. 



3.86 g. ammonium nitrate (In Series F substituted by NaNOs) 

 2,7 g. potassium sulphate ( „ „ „ partly besides K^COg) 

 0.5 g. ferric hydrate. 



i). It might therefore be supposed that carbonic acid of the soil-air suffices to render thia 

 phosphate available to the roots, while for bone dust a more powerful acid seems to be necessary to 

 render it thoroughly available. 



2). Also the acidity of the rootlets doubtless plays a part. 



3). The bone dust (steamed and partly deprived of glue) was of extreme fineness, <:o.5 m.m. 

 and contained 1.39 % N, 29.58 % P2O5, 37.8S % CaO and 1.27 % MgO. 



The magnesit contained 47.05 % MgO. 



The other manuring compounds were chemically pure. 



