372 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
(2) Tlie percentage of nitrogen in the dry mould of each nine-inch layer, as deter¬ 
mined by the soda-lime method ; 
(3) The calculated nitrogen per acre in pounds ; 
(4) The difference in amount between the two plots. 
The recorded amounts of dry soil per acre at each depth are the averages calculated 
from direct experimental data relating to the point, obtained in the case of three 
samples taken at each depth, from each of 22 plots. The determinations, and the 
estimates of the nitrogen per acre, in the respective soils, do not include the amount 
in roots separated from the soil-samples. Whilst, however, from the first nine inches 
of the unmanured soil 0'32 per cent, of roots was separated, in the corresponding layer 
of the farmyard-manured soil only 0'24 per cent, was found. There would, therefore, 
be no further accumulation in the manured soil due to this source. In the lower 
depths, again, the amounts of separated roots were very inconsiderable. 
Table XXI.—Estimated amount of dry soil per acre at each depth ; Nitrogen per 
cent, in the dry soils, and estimated Nitrogen per acre, at each depth. 
Nitrogen. 
Per cent, in dry soil. 
Per acre. 
Average dry soil 
per acre, 
exclusive of 
Plot 2. 
Plot 2. 
stones. 
Plot 3. 
Unmanured 
continuously. 
Farmyard 
manure 
8 years; 
unmanured 
Plot 3. 
Unmanured 
continuously. 
Farmyard 
manure 
8 years ; 
unmanured 
Plot 2. 
+ or — 
plot 3. 
12 years. 
12 jears. 
lbs. 
Per cent. 
Per cent. 
lbs. 
lbs. 
lbs. 
First depth, 1-9 inches 
2,183,375 
0-2565 
0 2800 
5600 
6113 
+ 513 
Second deph, 10-18 inches . 
2 835,339 
0-0724 
0 0849 
2053 
2407 
+ 354 
Third depth, 19-27 inches 
2,964,176 
0-0458 
0 0473 
1358 
1402 
+ 44 
Fourth depth, 28-36 inches . 
3,049,436 
0 0425 
0-0402 
1296 
1226 
- 70 
Fifth depth, 37-45 inches. . 
3 104 583 
0-0381 
0 0337 
j 1183 
1046 
-137 
Sixth depth, 46-54 inches 
3,080,909 
0 0376 
0 0319 
1158 
9S3 
—175 
Total. 27 inches . . . 
7,982,890 
9011 
9922 
+ 911 
Total, 54 inches . . . 
17,217,818 
12,648 
i 
13,177 
+ 529 . 
Adopting the foregoing results as to the accumulation of the nitrogen of the manure 
within the soil on the basis of the determinations to the total depth of 54 inches, the 
next table shows—the estimated amounts supplied in the farmyard manure, recovered 
in the increase of crop, and not so recovered; the residue found in the soil to the 
depth in question; and the amount not so recovered, either in the increase or in the soil. 
