2 On the Rain and Drainage-Waters at Rothamsted. 
loss of nitrogen thus observed might be to a great extent due to 
the washing out of nitrates from the soil during heavy rain.* 
An excellent opportunity of testing the soundness of this conclu- 
sion was afforded by the experiments in Broadbalk Field, this 
field having been for many years cropped with wheat, manured 
with various kinds of manure, and being furnished with a com- 
plete system of drain-pipes. The investigation of the drainage- 
waters from this field commenced in 1866. Before speaking 
of the results we must briefly describe the conditions of the 
experiment. 
1. The Experimental Field. 
Broadbalk Field contains about 13^ acres of arable land, of 
which only llf acres are now under exact experiment. The field 
lies in " lands," each 4| yards wide ; two adjoining lands form 
the two halves, a and b, of one plot. Both on the extreme right 
and left of the field there are, however, a few plots consisting 
of one land only. The length of the principal plots (Nos. 2-19) 
is 352 yards ; the area of each " land " is thus acre. 
The field was laid with drain-pipes in 1849, but without, at 
that time, any intention of employing them for experimental 
purposes. A drain was laid down the centre of each plot, from 
Plot 2 to Plot 18, the course of the drain lying under the furrow, 
separating the two lands of which each plot consists. A drain 
was also laid along the outer edge of Plot 19, which consistevl 
at that time of one land only. The drains were thus 8j yards 
apart. 
A plan of Broadbalk Field will be found opposite the first 
page. The thick parallel lines represent the side-boundaries 
of the plots, the lines across the field show the end-boundaries ; 
no manure has been applied for many years above or below 
these lines. The dotted parallel lines show the system of drain- 
pipes. The number of the plot to which each drain belongs is 
shown at the lower end of the plan. 
The general slope of Broadbalk Field is from west to east. 
The total fall of the drain of Plot 19 amounts to 12 feet 1^ inches ; 
on the other side of the field, in the middle of Plot 2, the fall is 
16 feet 9 inches in 352 yards. The inclination is but small in 
the upper part of the field, it occurs chiefly in the lower five- 
eighths of its length. The drains deliver entirely at the lower 
end of the field. At this end there is a small fall of 1 foot 
9| inches from Plot 19 to Plot 2. 
The drain-pipes employed were those known as the " horseshoe 
and sole ; " the internal diameter of the drain is about 2 inches. 
* Sec the Srcond Report on the Growth of Barley, alroatly mentioned, pp. 
331-345 ; also " Our Climate and our Wheat Crops ; " this ' Journal,' 1880, p. 199. 
