FOOD OF PLANTS IN GENERAL. 487 



containing nitrogen consists in the separation of the nitrogen in the 

 form of ammonia ; thus alone, each perishing generation would produce 

 enough nitrogen to furnish the next generation with an equal amount. 

 It is first given to the atmosphere in the form of ammonia, from which 

 it is received by plants in order to be again introduced into the circle of 

 organic existence. We know also from the researches of Daubeny and 

 Jones that ammonia is one among those gases which issue in large 

 quantities from volcanic strata.* By this means large additions are 

 made to the stores of ammonia obtained from its sources. As yet no 

 experiments have been made respecting the amount of ammonia con- 

 tained in the air, but it is known to vary much more with locality and 

 at different times than does carbonic acid. Those who have had any 

 experience in chemical labours, know how very difficult it is to exclude 

 ammonia, which penetrates every where. Every bottle of hydrochloric 

 acid that is not very tightly secured, every bottle of sulphuric acid 

 that has not been perfectly cleaned, affords, in a crust of ammonial salts 

 which forms upon it, the proof of this. All water, especially rain 

 water, and still more snow, contains ammonia. 



The most striking example of the production of nitrogen without 

 the same having been first furnished in the form of manure, is found in 

 irrigated meadows (Rieselwiesen), which annually yield from forty to 

 fifty Ibs, of nitrogen in organic compounds f, whilst on an average the pro- 

 duce of manured land yields only thirty-one Ibs., and after subtracting 

 that which was contained in the manure, "only seventeen Ibs. As we 

 have already seen, plants cannot draw this nourishment from the organic 

 elements of the soil, and this is especially the case with nitrogen. This 

 is seen in mountain districts and meadow lands which are employed only 

 for the breeding and rearing of cattle, and which yet allow more nitrogen 

 to be carried from them than is obtained by any other mode of tillage. 

 It is also confirmed by the amount of nitrogen contained in plants being 

 wholly independent of the amount of the nitrogen supplied by manure. 



In the south, and more especially in the central parts of Russia, the 

 agriculture carried on by the peasantry is of the lowest kind. Manure, 

 where used at all, is exclusively confined to garden and flax tillage ; the 

 fields are never manured. Hence their produce is only from five to six 

 fold. f Yet each acre yields in the harvest 14^ Ibs. of nitrogen ; and in Cen- 

 tral Russia, where we may suppose the land to have been in cultivation for 

 1000 years, each acre must have yielded, without any compensation, 

 14, 500 Ibs. of that substance. The export of corn from Odessa in 

 the year 1827 contained not less than 755 million Ibs. of nitrogen. || 



* The Ammoniacal Grotto near Naples (Gazette Medicale de Paris, No. 49. Froriep's 

 Notizen: 28, 257.). 



f Irrigated meadows ( Rieselwiesen), according to the German farmers, Linke, 

 Scbwerz, &c., yield from 30 to 40 centners of hay. Dried hay, according to Boussin- 

 gault, contains 1'29 per cent, of nitrogen. 



f This poverty of crop is not universal. In some districts of the Ukraine no manure 

 is used. The straw is burned. The corn grows so vigorously that the stalks are as 

 thick as that of the reed, and the leaves resemble those of maize ; whilst crop after crop 

 is drawn from the same soil, with only one ploughing between the harvest and the 

 sowing. (Loudon.) 



The sowing of li Berlin bushels of corn yield six bushels at harvest, or 540 Ibs. 

 The produce of corn to straw is as one to two, making 1080 Ibs. of straw. Wheat 

 dried at 1 10 Cent, yields, according to Boussingault, 85*5 per cent, of dry material, 

 and thus 2-3 per cent, of nitrogen ; the wheat straw 74 per cent, of dry matter, and in 

 that 0-4 per cent, of nitrogen. 



|| Odessa exported in the year 1827 1,200,826 Tschetwert of wheat, 39,940 Tschet- 



i I 4 



