Some Ob.'ifi vattoita on Ma.nuvlns ■\\ltl\ Bont^Mliist. 



Average of three parallel pots. 



117 



If we now assume the total yield with the manure of the group IV to 

 'be= 100, we obtain the following ratio : 



From these results, which differ partly from those obtained with plain 

 •sand-culture (see above) it may be concluded that the harvests of barley 

 obtained on sandy soils with done dust and sodium nitrate as manure do 

 7iot shotu great differences ivhen in one case tJie potassa is supplied as 

 potassium sulphate and in the other as potassium carbonate. On one soil, 

 the result was nearly equal, while on the .second soil, potassium sulphate 

 yielded a somewhat better result. Also the potassa in the form of wood 

 ash yielded a result not behind the other case. Wood ash and bone dust 

 may therefore be applied together. 



This behavior of potassium carbonate in the soil manured with bone 

 dust required some further chemical examination, for there was a direct 

 action of it on the bone dust possible with gradual formation of potassium 

 phosphate and calcium caibonate. 



■^ The weight of one plant in the group \ would therefore be 7 g. in the air-dry state and of 

 the group IV 8 g. In the first experiment whtn bone dust was applied together with ammonium 

 nitrate and gypsum the average weight of one plant was also 7 g. In the second experiment, the 

 average weights of one plant in the pots I and IV were again 7 g. 



