6 
SIR J. B. LAWBS AND PROFESSOR J. H. GILBERT ON THE 
Table II.—Nitrogen as Nitric Acid per acre, lbs., in the soils and subsoils of some 
experimental plots, without nitrogenous manure for more than 30 years. 
Hoosfield, Rothamsted. Soil samples collected July 17-26, 1883. 
Depths. 
Unmanured. 
Series I. 
Mineral manures only. 
Trifolium 
repens, 
+ or —. 
Wheat land. 
+ or —. 
Trifolium rejpem» 
Wheat- 
fallow land. 
Trifolium 
repens. 
Plot 4. 
Vida 
sativa. 
Plot 4. 
Vida 
sativa. 
Plot 6. 
Vida 
sativa. 
Plot 4. 
Vida 
sativa. 
Plot 6. 
inches. 
lbs. 
lbs. 
lbs. 
lbs. 
lbs. 
lbs. 
lbs. 
1- 9 
19-85 
30-90 
12-16 
10-22 
-f 11-05 
- 18-74 
-- 20-68 
10- 18 
8-05 
27-73 
4-11 
2-72 
+ 19-68 
- 23-62 
- 25-01 
19- 27 
2-47 
8-44 
1-37 
1-08 
+ 
5-97 
- 7-07 
- 7-36 
28- 36 
2-70 
7-64 
1-67 
1-52 
+ 
4-94 
- 5-97 
- 6-12 
37- 45 
1-62 
9-07 
4-58 
2-51 
+ 
7-45 
- 4-49 
— 6-56 
46- 54 
3-57 
8-77 
6-37 
4-42 
+ 
5-20 
- 2-40 
- 4-35 
55- 63 
3-84 
7-92 
7-16 
4-52 
+ 
4-08 
- 0-76 
- 3-40 
64- 72 
2-28 
8-34 
5-95 
4-92 
+ 
6-06 
- 2-39 
- 3-42 
73- 81 
1-48 
8-27 
4-54 
4-81 
+ 
6-79 
- 3-73 
- 3-46 
82- 90 
1-76 
9-95 
5-32 
5-14 
+ 
8-19 
- 4-63 
- 4-81 
91- 99 
2-94 
9-16 
5-66 
6-40 
+ 
6-22 
- 3-50 
- 2-76 
100-108 
1-84 
9-51 
5-32 
6-46 
+ 
7-67 
- 4-19 
- 3-05 
Total 
52-40 
145-70 
64-21 
54-72 
+ 93-30 
- 81-49 
- 90-98 
These wheat-fallow and leguminous plots are absolutely adjoining; and by their 
previous treatment their surface soils had become extremely poor in nitrogen. The 
results have been discussed in detail in the paper in the Transactions of the Chemical 
Society, and must only be briefly summarised here. Table I. shows that, for about 
30 years, the Trifolium repens soil had yielded in crops nearly twice as much nitrogen 
per acre as the wheat-fallow soil. Yet it is seen that, whilst the wheat-fallow soil 
contained, down to the depth of 9 feet, only 5 2’4 lbs. of nitrogen as nitric acid per 
acre, the Trfolium repens soil contained 145’7 lbs. to the same depth. In other 
words—the Trifolium repens soil, from which so much more nitrogen had been 
removed, contained 93'3 lbs. more nitrogen as nitric acid than the wheat-fallow soil. 
Now, excepting that the leguminous crop soil had received mineral manures, and 
the wheat soil had not, the characteristic difference in the history of the two plots 
was, that the one had grown a gramineous crop alternately with fallow for more than 
30 years, and the other had, during the same period, besides growing 6 gramineous 
crops, and being frequently fallow, been sown 12 times with red clover, and, during 
the immediately preceding 6 years, 4 times with white clover. That is to say, the 
chief distinction was, that the one plot had, especially in the earlier and the later years, 
grown a leguminous crop, whilst the other had not; and it is under these circum¬ 
stances that the leguminous crop soil is found to contain, down to 108 inches, nearly 
3 times as much nitrogen as nitric acid ns the gramineous crop soil. 
