7 



0*4 gramme a drop of 69 and 75 per cent, respectively. In both cases 

 not only had no nitrogen been appropriated by the plants from the dun<* 

 but it was oven found that the plants upon the dunked pots contained 

 less of this element than the plants grown without any added nitrogen. 

 Even assuming that the albuminoid nitrogen in dung is absolutely in- 

 operative, there still remained an appreciable amount of ammoiuacal and 

 amide nitrogen which, if applied alone, would certainly havo 

 produced an increase in the crop. In some way or other, then, the 

 action of this active nitrogen was hindered and the results on certain of 

 the other pots throw some light on this matter. In Maercker's experi- 

 ments it was fouud that whereas 0"75 gramme of nitrogen in the forms 

 of nitrate of soda and urea respectively were capable of more than 

 doubling the yield when applied to the soil without dung, their action 

 was very much less when they were added to soil that contained either 

 horse, ox, or- cow-dung. By a series of experiments and calculations 

 Maercker showed that from 12 to 47 per cent, of the nitrogen in nitrate 

 of soda was dissipated through the contact with the various forms of 

 dung in the soil, and the loss was greatest when the largest quantity of 

 dung was used. 



Wagner also tested the action on mustard of nitrate of soda alone 

 and in conjunction with horse-dung, and found that whereas 05 per 

 cent, of the nitrogen in the nitrate was recovered when it was applied 

 alone, only 30 per cent, was recovered when it was added to 

 a soil holding a moderate dressing of horse-dung. And not only did the 

 horse-dung greatly depress the nitrogen-recovery from nitrate of soda, 

 but it acted in a precisely similar manner when the active nitrogen wa9 

 furnished to the soil in the form ot urea and chopped lucerne. With 

 nrea the nitrogen recovery was 60 per cent, when used alone, but 

 only 49 p<-r cent, when used with dung ; while in the case of chopped 

 lucerne the respective figures were 38 and b\ 



In another very extensive and thorough going experiment witb 

 oats, Wagner tested the result of the application of nitrogen to pots 

 holding eighteen and a half kilogrammes of soil, the nitrogen beiug de- 

 rived from nitrate of soda, sulphate of ammonia, blood meal, chopped 

 grass, cow urine, horse and cow-dung, and various samples of farmyard 

 manure. The figures are too extensive to be dealt with as a whole, but 

 attention may be called to some of the results obtained. Thus, when 

 nitrate of soda was used alone to the extent of two and four grammes 

 of nitrogen per pot, the nitrogen recovered in the crop increase was 77 

 er cent, and 59 per cent, respectively. That the larger dose of nitrate 

 ad still ample opportunity to act is evident from the fact that it increased 

 the average yield from 244.3 grammes (the yield with the smaller dress- 

 ing) to *385.9 grammes per pot. The fresh horse-dung, containing two 

 grammes of nitrogen, produced 9.1 grammes less yield than the unma- 

 nured pots, and the produce also contained less nitrogen. When 2 

 grammes of nitrogen in horse-dung were added to pots containing 2 

 grammes of nitrogen derived from nitrate of soda there was a depression 

 of the yield from 244.3 grammes to 177 grammes ; when the dung was 

 added to pots holding sulphate of ammonia there was a drop in the 

 yield from 231,5 grammes to 165.7 grammes ; when added to 

 pots getting chopped grass the drop in produce was from 



