On the Rain and Drainage-Waters at Rothamsted. 67 
1877-8 to 1880-1, is 41-81 lbs., equal to 268 lbs. of ordinary 
nitrate of sodium per acre. 
10. The amount of chlorine in the drainage from the drain- 
gauges is approximately the same as in the rainfall. 
11. The advantage of a bare fallow is largely due to the 
production of nitrates in the soil ; in fields in bare fallow at 
Rothamsted 50 lbs. per acre of nitrogen as nitrates have been 
found at the end of summer in the first 20 inches. If followed 
by a wet winter, bare fallow must result in a serious loss of soil 
nitrogen. 
Drainage-waters from Land Manured and Cropped 
WITH Wheat. 
12. The drainage-water passing through a natural soil is of 
two kinds : — 1. Surface-water passing downwards through open 
channels. 2. The discharge from the saturated soil. The first 
is much weaker than the second, save when soluble manures 
have been recently applied to the surface. 
13. The annual average loss of lime and magnesia by drainage 
from the continuously unmanured wheat-plot, is apparently 
about 223 lbs. ; where 400 lbs. ammonium-salts are applied, the 
loss is 389 lbs. ; where sulphates of sodium, potassium, and 
magnesium are also added, the loss is still greater ; the two 
last-named salts exerting most influence. Nitrate of sodium 
does not apparently increase the loss of lime. 
14. The chlorine and soda applied in manure are retained 
to only a small extent, either by the wheat-crop or the soil ; 
sulphuric acid is retained to a somewhat greater extent. Phos- 
phoric acid and potash are very perfectly retained, the part 
unassimilated by the crop being held by the soil, chiefly in the 
upper layers ; this is especially true of phosphoric acid. 
15. The quantity of nitric acid lost by drainage from un- 
manured land cropped with wheat, is far smaller than that lost 
by uncropped land, the crop assimilating the nitrates formed. 
In summer the drainage-waters contain little or no nitrates ; after 
harvest nitrates reappear, and are found in the waters through 
the winter. 
16. When ammonium-salts are applied to land, the ammonia 
is at first retained by the soil, while the sulphuric acid or 
chlorine passes into the drainage-water, chiefly as calcium salts. 
17. The conversion of the ammonia into nitric acid commences 
almost immediately after the application of ammonium-salts to 
wet soil, the conversion is apparently complete in a few weeks 
if wet weather follows. The nitrogen of rape-cake is more 
slowly converted into nitric acid. 
F 2 
