On the Rain and Drainage - Waters at Rothamsted. 
61 
more or less — to be contributed by seed, and by rain and con- 
densation from the atmosphere. Of this about 2 lbs. will be 
due to seed, leaving not much more to be otherwise accounted 
for than has been shown to be annually supplied in rain and 
the minor deposits from the atmosphere. 
Assuming 32 lbs. of nitrogen to be annually contributed by 
seed, rain and condensation, and the soil, to the vegetation and 
the drainage of the plots receiving nitrogen in manure, there 
is, as has been shown, a considerable amount of the total 
nitrogen available, which is not accounted for in the crop and 
drainage. Deducting the amounts in crop and drainage of 
Plot 5 from those of the other plots, as in Table LIII., it was 
shown that with 86 lbs. of nitrogen supplied in 400 lbs. am- 
monium-salts, there remained from 34 to 42 lbs. unaccounted 
for in increase of crop and drainage. Or, if we add the 32 lbs. 
assumed to be available from other sources to the 86 from the 
ammonium-salts, we have 118 lbs. annually available from all 
sources ; and, as we have under the most favourable conditions 
of mineral supply and growth only about 80 lbs. in total crop 
and collected drainage, there remain, on this mode of reckoning, 
about 38 lbs. of the 118 annually unaccounted for; and with 
excess of nitrogen in manure very much more. 
As on these modes of reckoning, the same amount is assumed 
to be available from seed, atmosphere, and soil, as to Plot 5, it 
is clear that the amount in the soil of the different plots in 
excess of that on Plot 5, is to be reckoned as so much reduction 
of the amount otherwise unaccounted for. So far as can be judged 
from the results already at command, it would appear that, with 
86 lbs. of nitrogen supplied in manure, and the more favourable 
conditions of mineral supply and growth, perhaps one-third of 
the deficiency will be accounted for in the soil. There would 
still remain, therefore, say 25 lbs., more or less, annually 
unaccounted for, and the amount will be the greater the more 
defective the conditions of growth, or the greater the excess in 
manure. The latter are, nevertheless, the conditions under which 
the collected drainage accounts for the greatest actual quantity. 
Either then the amounts of nitrogen estimated to be lost by 
drainage are too low, or there is some other source of loss. 
With regard to the first supposition, it is admitted that there 
is uncertainty in the estimates of the total amount of drainage 
passing from the land ; that it is a question how far the com- 
position of the drainage collected from the pipes represents that 
of the total drainage ; and that at any rate the determinations 
of nitric acid in the drainage-waters are but few, indeed far too 
few, for the long series of years during which the nitrogenous 
manures were sown in the autumn. On this point it may be 
