QUESTION OE THE SOURCES OE THE NITROGEN OE VEGETATION. 
23 
In the case of the wheat-fallow, and rotation clover land samples, to which the 
bottom division of the Table refers, there was a seeding with 0'2 gram of the garden 
soil after the extraction of the already existing nitric nitrogen, and before the first 
period of exposure ; and there was again a similar seeding of the “ seeded ” lots, after 
the third period of exposure in the case of the wheat-fallow subsoil, and after the 
fourth period in that of the rotation clover land subsoil. There was also added, in 
the case of the wheat-fallow subsoil after the third, and in that of the clover subsoil 
after the fourth period, 0‘8 gram of a mixture of 1 part potassium phosphate, 1 part 
magnesium sulphate, and 5 parts calcium carbonate; the mixture containing as 
impurity 0'000616 gram nitrogen per gram. 
Table X. 
—Results showing the amount of the Nitrification of the nitrogen of subsoils. 
Nitro¬ 
gen 
in fine 
dry 
soil. 
Nitrogen as nitric acid per million fine dry soil. 
Total. 
Origi¬ 
nal. 
Periods of exposure. 
1st. 
2nd. 
Srd. 
4th. 
5 th. t 
Wheat-fallow subsoils, collected July 17-26, 1883. 
Mixture of Srd-12th depths 
Per 
cent. 
Days. 
Days. 
Days. 
Days. 
Days. 
Days. 
Hole 1. 
•0492 
0-77 
28 
•106 
28 
•109 
28 
-237 
28 
•247 
246 
•084 
358 
•783 
„ 2 . 
•0562 
0-48 
28 
-071 
28 
•208 
28 
•043 
28 
•162 
246 
•225 
358 
•709 
,, 4. 
•0484 
0-54 
28 
•127 
28 
•166 
28 
•066 
28 
•299 
246 
•224 
358 
•882 
Means .... 
•0513 
0-60 
28 
•101 
28 
•161 
28 
•115 
28 
•236 
246 
•178 
358 
•791 
Leguminous crop subsoils, collected July 17-26, 
1883. 
Mixture of 3rd-12th depth 
S. 
Trifolium repeiis. Plot 4 
•0592 
2-50 
28 
•132 
28 
•083 
28 
•156 
28 
•303 
246 
•338 
358 
1-012 
Viciasativa. „ 4 
•0508 
1-63 
28 
•145 
28 
•015* 
28 
•185 
28 
•379 
246 
•375 
358 
1-099 
Vicla sativa. „ 6 
•0360 
1-40 
28 
•108 
28 
•079 
28 
•176 
28 
•276 
246 
•421 
358 
1-060 
Means .... 
•0487 
1-84 
28 
•128 
28 
•059 
28 
•172 
28 
•319 
246 
•378 
358 
1-056 
Wheat-fallow samples collected May 7 
, 1886 
, at a depth of 5 feet. Clover land samples collected April 16, 1886, 
at 
7 feet 4 inches deep. 
TT 1 j f Wheat-fallow 
Unseeded 
•0768 
•0772 
0-720 
0-618 
28 
28 
•053 
•077 
35 
35 
•052 
•060 
49 
28 
•107 
-134 
129t 
30 
[•312]t 
•177 
139 
[358] 
241 
260 
•524 
•806 
Means . . 
•0770 
0-669 
28 
-065 
35 
•056 
39 
•121 
79 
-245 
„ , , j Wheat-fallow 
[ Clover laud 
•0768 
0-714 
28 
-140 
35 
•081 
49 
•118 
129t 
r-3581 
241 
•697 
•0772 
0-626 
28 
•262 
35 
•103 
28 
•437 
30 
•192 
139 
[•580] 
260 
1-574 
Means . . 
•0770 
0-670 
28 
•201 
35 
•092 
39 
•278 
79 
•275 
Referring to the results, it is in the first place to be observed that there is very 
considerable variation in the percentage of total nitrogen in the different subsoils. 
* Probably too low. 
t The number of days represents the periods of e.xposure, the periods of activity are uncertain. 
J The figures given between brackets thus [ ] show the results obtained after the addition of the mineral mixture described 
in the text. 
