QUESTION OF THE SOURCES OF THE NITROGEN OF VEGETATION. 
5 
Table I.—Estimated yield of Nitrogen per acre, in lbs,, in wheat alternated with 
fallow, and in various leguminous crops without nitrogenous manure. 
Onmanured. 
Mineral manures only. 
Fallow-wheat. 
Trifolium repms. 
Vida saliva. 
Prelimmary period :—Wheat and fallow, 27 years, 1851-77. Red clover, &c., &c., 
29 years, 1849-77. 
1 
Ihs. 
lbs. 
Average per acre per annum . . 
17 
32 
Experimental period. 
lbs. 
lbs. 
lbs. 
1878 . 
29 
0 
51 
1879 . 
Fallow 
82 
46 
1880 . 
24 
0 
58 
1881. 
Fallow 
8 
65 
1882 . 
18 
74 
146 
1883 . 
Fallow 
0 
101 
Total, 6 years. 
71 
164 
467 
Average annual. 
12 
27 
78 
The next Table (11.) shows the amounts of nitrogen as nitric acid found in the soils 
and subsoils of the several plots under the conditions above described. 
