QUESTION OF THE SOURCES OF THE NITROGEN OF VEGETATION. 75 
The little influence of the mineral, and the great influence of the nitrogenous 
manure, on the oats, and again the marked influence of the mineral, and the little effect 
of the nitrogenous manure, on the Leguminosae, are here very strikingly illustrated. 
Referring to the amounts of nitrogen in the crops of sand-peas grown in the washed 
sand, as given in the table at the top of page 74, Wolff states that the 19 peas sown 
contained 1*542 gram diy substance, and he estimates the amount of nitrogen in the 
seed sown at only 0*0647 gram; the quantity of nitrogen so provided was, there¬ 
fore, quite immaterial in proportion to that in the crops. 
The amounts of nitrogen in the clover crops of Experiments 2 and 4 are estimated to 
correspond to 334 and 376 kilog. per hectare, to which one-third should be added for 
stubble and roots. The beans appear not to have collected so large a quantity of 
nitrogen in 1886 as the clover and the lupins; and it may be mentioned that whilst 
the 54 bean seeds sown would contain 1*0353 gram of nitrogen, the same number of 
lupin seeds would contain only 0*5912 gram. 
Some experiments by Stuecker with yellow lupins are quoted as showing con¬ 
siderable gains of nitrogen. 
With regard to the numerous results recorded in his paper, Wolff admits that 
they are not satisfactory in all respects, those of different years not being always 
accordant. But the special object was to compare the growth of cereals with that of 
Papilionacese, over a series of years, in a soil poor in combined nitrogen, or containing 
known amounts of it; and the influence of the various seasons was different on the 
different crops. 
The following table gives estimates of the amounts of nitrogen in the crops, more 
(+) or less (—) than supplied in the seed and manure, calculated per hectare; the 
selection of experiments being the same as in the case of the results given in the table 
at the top of p. 74 :— 
Estimated Nitrogen, in kilograms per hectare, in crops more (+) or less (—) than in 
seed and manure. 
■ 
“ C ” series, unwashed sand. 
‘ B ” series 
washed sand 
Oats. 
Lupins. 
Field- 
beans. 
R d 
clover. 
Sand-peas. 
Kilog. 
Kilog. 
Kilog. 
Kilog. 
Kilog. 
1. Unmanured. 
- 9-0 
+ 88-3 
+ 57-7 
+ 135-8 
-b 84-7 
2. Mineral manure. 
- 8-3 
+ 359*3 
+ 146-2 
+ .334-1 
-b 464-9 
3. Mineral manure, and nitrate. 
- II-7 
+ 158-8 
-f~ 54‘b 
-1- 318-8 
-b 643-5 
4. Mineral manure, and nitrate . 
- 17-6 
-h 195-8 
- 10-4* 
-b 242-9 
+ 668-1 
* Given in error as -|- 89’5 by Wolff, the nitrogen of tbe manure of Experiment 3 instead of that of 
Experiment 4 having been deducted. 
