,iS,i now CROPS FF.Kn. 



generally which have not been recently manured, ammonia 

 and nitric acid are the exclusive feeders of vegetation with 

 nitrogen. Such a view is not indeed absohitely demon- 

 strated, but the experiments alluded to render it in the 

 highest degree probable, and justify us in designating the 

 organic nitrogen for the most part as inert, so far as vege- 

 table nutrition is concerned, until altered to nitrates or 

 ammonia-salts by chemical change. 



To comprehend the favorable results of garden-culture 

 in such a soil, it must be considered what a large quantity 

 of earth is at the disposal of the crop, viz., as Boussingault 

 ascertained, 57 lbs. for each hill of dwarf beans, 190 lbs. 

 for each hill of potatoes, 470 lbs. for each tobacco plant, 

 and 2,900 lbs. for every three hop-plants. 



The quantity and condition of the nitrogen of Boussin- 

 gault's garden soil are stated in tlie subjoined scheme. 



Available \ Ammonia 0.00220 per cent = Nitrogen 0.00181 per cent I „ nmn „ f 

 nitrogen "(Nitric acid 0.00034 " '• = " 0.00009" " )' U-UUi.i per ct. 



Inert nitrogen— of organic compounds 0.2591 " " 



Total nitrogen 0.2610 per ct. 



Calculation shows that in garden culture the plants 

 above named would have at their disposal in this soil quan- 

 tities of inert and available nitrosren as follows : 



Indirect Feeding of Crops by the Organic Nitrogen 

 of tlie Soil. — In what has been said of the oxidation of 

 the organic matters of the soil, (whereby it is probable 

 that their nitrogen is partially converted into nitric acid,) 

 and of the effect of alkalies aud lime upon them, (whereby 

 ammonia is generated,) is given a clue to the understand- 



