40 On the Rain and Drainage - Waters at Rothamsted. 
nitrogen as nitrates per million of water, with a maximum of 
68*9 ; this will be equivalent to an average loss of 11"8 lbs. 
of nitrogen, or 75"6 lbs. of nitrate of sodium per acre for each 
inch of drainage. These quantities much exceed those yielded 
bj the corresponding plots receiving ammonium-salts. It is 
unfortunate for the present purpose that Plot 9 is not treated 
alike on its two halves, for while the " a " portion receives the 
mixed mineral manure, the " h " portion is unsupplied with ash- 
constituents. Half the plot is thus in a similar condition to 
Plot 7, and the other half to Plot 10 in the ammonia series, while 
the drainage-water is derived indifferently from both halves. 
The results yielded by the nitrate of sodium plot are, however, so 
distinct that we are left in little doubt as to its influence on the 
drainage-water. Although the largest wheat-crop in the field is 
yielded on an average by the half-plot 9 a, and consequently 
there must be on this half a large quantity of nitrogen taken up 
by the growing plant, the drainage-water contains, in nearly every 
recent season, more nitrate than that from Plot 10, where, as we 
have just seen, the waste of nitrogen reaches an exti'eme point. 
It appears, therefore, quite certain that when nitrate of sodium 
is applied to the Rothamsted soil a larger proportion of the 
nitrogen will appear in the drainage- water than when the same 
quantity of nitrogen is applied in the form of ammonium-salts. 
We turn next to the plots receiving nitrogenous manures in 
autumn, and first of Plot 15, which receives the same quantity of 
ammonium-salts as Plots 7, 10, 11, 12, 13, and 14, but with the 
difference that these salts are applied in October instead of in 
March. There being no active growth of the wheat-plant during 
the winter months, the nitrates produced from the ammonia on 
this plot remain unconsumed, and in the absence of much rain 
will accumulate in the soil. The drainage-waters from this plot 
thus generally reach a greater richness in nitrates than is the 
case with any other plot in the field. The nitrogen as nitrates 
in the water usually attains 60-70 per million as its maximum 
in the course of the winter, and has in one case reached 83*2. 
The nitrates in the soil being exposed to loss by drainage for 
five or six months before the active growth of the wheat-crop 
commences, a very great loss of nitrogen will ensue whenever 
the winter is wet and drainage abundant, as has been the case 
in two out of the three winters during the period under con- 
sideration. With wet winter seasons the crop grown on Plot 15 
is usually much smaller than that on Plot 7, where the ammonia 
is applied in spring. The comparative crops obtained in 
various years by autumn and spring applications of ammonium- 
salts have been already given in an earlier paper; see "Our 
Climate and Our Wheat Crops'" in this ' Journal,' 1880, p. 205. 
