378 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
The next table shows the estimates of the nitrogen—supplied in the manure, 
recovered in the increase of crop, determined in the soil, and not recovered in either 
the increase or the soil. 
Table XXVII. — Experiments on Wheat. Estimated Nitrogen supplied in the 
Manure, recovered in the increase of crop, determined as residue in the soil, 
and not recovered in either the increase or the soil, to the depth of 27 inches. 
Nitrogen of manure. 
Per acre. 
Per cent. 
Supplied in farmyard manure in 22 years. 
Recovered as increase of crops. 
lbs. 
4415 
470 
10-7 
Not recovered in increase. 
Residue determined by soda-lime in soil 27 inches deep 
3945 
2172 
89-3 
49-2 
Not recovered in increase or in soil. 
1773 
40-1 
Here we have, over the first 22 years of the wheat experiments, only 10 "7 per cent, 
of the supplied nitrogen estimated to be recovered as increased yield, against 14 - 6 per 
cent, over the last 20, of the first 28 years (see p. 374). There is about one-and-a-half 
time as large a proportion determined as residue in the wheat soil, and therefore a 
less proportion estimated as loss, than in the case of the hay-plot reckoned to the 
depth of 54 inches. On the other hand, if the latter be taken to only the same depth 
as the wheat plots—that is, to 27 inches instead of 54—the proportion of the supplied 
nitrogen estimated to remain as residue in the soil is greater, and that estimated as 
loss less, in the case of the permanent meadow than in that of the wheat plots. Thus, 
in the case of the wheat experiments, the loss of nitrogen, by drainage or otherwise, 
is estimated to be about 40 per cent, of that supplied; in that of the hay-plot 
reckoned to the same, or 27 inches of depth, 25'2 per cent., or to the depth of 
54 inches 49 per cent. 
It must be borne in mind that the whole of the estimates on this point, whether 
relating to wheat, to barley, or to grass, are based on the assumption that the 14 tons 
of farmyard manure annually applied contained 0'64 per cent., or 200 - 7 lbs., of 
nitrogen; and if it did not contain so much, the percentage recovered was of course 
greater, and that not recovered less, than the foregoing calculations indicate. But it 
is at any rate clear that only a comparatively small proportion of the nitrogen so 
supplied is recovered in the increase of crop. The residue actually determined in the 
soil is very large; and it is possible that the whole of the nitrogen existing as nitric 
acid, especially in the subsoil, is not accounted for by the soda-lime determinations. 
It is very remarkable, however, that notwithstanding this great ascertained accuinu- 
