On the Bain and Drainage - Waters at Rothamsted. 
37 
The considerable accumulation of nitrates that may occur in 
a dry winter is illustrated by the composition of the runnings 
in February 1880. All the analyses referred to will be found 
in Table XLVTI. The general character of the waters at 
different seasons of the year is also illustrated by Table XLVIII. 
The results yielded by the drainage-waters from plots receiv- 
ing ammonium-salts are full of interest. Soil, as is well known, 
has a wonderful retentive power for ammonia, and this is one 
reason why ammonia is so seldom present in drainage-waters. 
In Voelcker's and Frankland's analyses of Broadbalk waters 
mere traces of ammonia were found, the amount being generally 
below that in ordinary rain-water. Our own examinations of 
Broadbalk waters lead to the same conclusion. We have, how- 
ever, one instance in which ammonia was found in the drainage- 
water in considerable quantity. The usual dressing of 400 lbs. 
of ammonium-salts per acre had been applied to Plot 15 on 
October 25, 1880, and the manure ploughed in. Heavy rain 
occurred, during the night of the 26th, so that on the morning 
of the 27th all the drain-pipes, save those of Plots 2 and 19, 
were found running. The water collected from Plot 15 at 
€*30 A.M. contained nitrogen, as ammonia, equal to 9"0 per 
onillion ; a later collection at 1 P.M., contained 6 5 per million. 
Rain still continuing, collections of water were also made on the 
two following days. On the 28th the water collected at 6.30 A.M. 
■contained 2*5 per million of nitrogen as ammonia. On the 
59th, at 10'30 A.M., the quantity was 1'5 per million. Ammonia 
is absorbed by soil from a solution of salts of ammonium, only 
when the soil contains a sufficient quantity of some base capable 
of uniting with the acids of these salts. The Rothamsted soil 
contains but little chalk ; it was clearly unable to decompose the 
ammonium-salt sufficiently quickly to prevent loss of ammonia. 
It is evident that the first result of the application of am- 
anonium-salts to the Rothamsted soil is the chemical absorption 
■of the ammonia ; the acids of the ammonium-salts at the same 
time unite with the lime in the soil, and may be removed in 
the drainage-water. Thus the water mentioned above as con- 
taining 9 0 parts of nitrogen as ammonia, contained 146*4 parts 
of chlorine derived from the ammonium-salts. If the soil is 
sufficiently moist to allow of the reaction just described, nitrifica- 
tion of the absorbed ammonia will rapidly take place. In the 
instance before us nitrification had made distinct progress in 
40 hours. On October 10 the drainage-water from Plot 15 con- 
tained 8"4 of nitrogen per million in the form of nitrates. On 
the morning of October 27, about 40 hours after the application 
ol the ammonium-salts, the nitrogen as nitrates in the water had 
risen to 13 5 per million. By November 15, 21 days after 
