DR. SCHLEIDEN'S THEORY OF AGRICULTURE. 41 



never received anj' dunj? yields yearly 40-50 lbs. of nitrogen, 

 while the best ploughed land yields only about 31 lbs. The 

 plants for which most dung is used, as potatoes and turnips, are 

 in fact proportionally the poorest in nitrogen. 



The vast Pampas of Buenos Ayres, since the introduction of 

 horses and oxen, have yielded for their support almost incal- 

 culable quantities of nitrogen, millions of pounds being annually 

 carried off in the form of hides, horns, &.c. ; and yet there is no 

 decrease in tiie produce of the country, which must have been 

 the case had the plants depended upon the soil for the requisite 

 ammonia. 



The Swiss Alps, the meadows of East Friesland and Holland, 

 receive no organic nitrogenous matter, for the dung of the 

 beasts whicii feed on them contributes always less than they have 

 received. A horse, according to Boussingault, consumes in its 

 food in 24 hours 78 -6 drams of nitrogen ; the excrement con- 

 tains only 65 drams; 13' 5 drams are given off by perspiration 

 in the form of ammonia. In the cow the nourishment in the 

 same time contains 113*7 drams, the nitrogen in the excrement 

 and milk amounts to 98 '4 drams, and that of the perspiration to 

 15 -2 drams. In other worils, the cow returns to the meadow 

 for the 710 drams of nitrogenous organic matter which she con- 

 sumes, only 614 7. JSevertheless, these alps and meadows con- 

 tribute annually enormous quantities of nitrogenous matter in 

 the shape of hay and cheese. This production of nitrogen must 

 therefore be independent of the soil. 



Another proof appears as follows : — Since the manure is 

 intended for the supply of several successive years, the content 

 of nitrogen in the crop, as the decomposition proceeds, must 

 year by year regularly rise or fall. It is, however, quite inde- 

 pendent of the time which may have elapsed since the manure 

 was applied, as appears from the following table taken from 

 Boussingault : — 



Nitrogen per Acre, 

 lb. 



Year 1. Potatoes 24,75 



„ 2. Wheat 18,92 



„ 3. Clover 45,21 



„ 4. Wheat and stubble turnips 29,93 



„ 5. Peas 52,63 



„ 6. Rye 17,43 



In two five-year courses, and one of six years, the ground re- 

 ceived yearly, per acre, 21-90 lbs. of nitrogen in dung. The 

 excess of nitrogen in the produce over that in the dung was 

 yearly— 



