Some Obieivatiuiis oii. Manuring witli Bon©-tlu«t. 



Ill 



nitrate^* and 2 g. bone dust^^ were applied as general manure to each pot. 

 While 1. 61 g potassium carbonate^^ was added to each of the first two pots, 

 each of the second two pots received as much wood ash*' as corresponded to 

 potassium carbonate so that the potassa content was equal. Each of the 

 third two pots with wood ash received less bone dust than the others, since 

 the wood ash itself contained 3.5 % P2O5. This amount was calculated as 

 bone dust and subtracted from the 2 g. bone dust applied to the other 

 pots ; probably the phosphoric acid in the wood ash is also present chiefly 

 as tertiary calcium phosphate. To make up the difference in nitrogen the 

 amount of sodium nitrate was raised to 6.2 g. In each of the fourth two 

 pots, the potassa was applied as sulphate^' in doses equivalent to the 

 potassium carbonate, applied to the others. The following table gives the 

 quantitative data in regard to manuring : 



On Nov. 6, twenty seeds of sixsided barley were sown per pot, and 

 after nine days the young shoots came up almost stimultaneously. The 



i). Sodium nitrate (i6 % N) was intentionally applied as a source of nitrogen, since am- 

 monium sulphate, being physiologically acid, would have interferred with the alkalinity of the 

 manure (potassium carbonate and wood ash), the effect of which was to be observed. 



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

 and contained 2.71 % N and 27.73 % P.jOg. 



3). The potassium carbonate contained 65 % K2O. 



4). The wood ash contained 11 % K.2O, and 3.50 % PvOs. 



5). The potassium sulphate contained 54 % KjO. 



