On the Rain and Drainage - Waters at Rothamsted. 
327 
cultivation. In 1870 the soil was bare fallow, save that two rows 
of barley (manured with guano) were sown by mistake along 
one end of each of the plots afterwards isolated as drain-gauges. 
In 1869 the crop was wheat unmanured. In 1868 swedes were 
grown with guano and superphosphate. The few crops imme- 
diately preceding the swedes were all cereals, grown with 
artificial manures, generally with guano. 
The soil was sampled to the depth of 54 inches, while lying 
as bare fallow in June 1870. The amount of nitrogen found 
in each successive 9 inches of dry soil, stones removed, was as. 
follows : — 
Table XXVI. — Nitrogen found in the Soil of the Deain-Gauges. 
Depth. 
Nitrogen per cent. 
In Soil dried at 
212°. 
Nitrogen in lbs. 
per Acre. 
First 
9 inches .. 
0-1463 
3499 
Second 
9 „ .. .. 
0-0781 
2083 
Third 
9 , 
0-0757 
1902 
Fourth 
9 „ .. .. 
0-0757 
1825 
Fifth 
9 „ .. .. 
0-0611 
1668 
Sixth 
9 „ .. .. 
0-0569 
1359 
Total 54 inches . . 
12,336 
The surface-soil was apparently rather richer in nitrogen 
than the ordinary arable soil of the Rothamsted farm, the first 
9 inches of which usually contains about 0-135 per cent. 
Besides the constituents originally present in the soil we must 
bear in mind that it annually receives from the atmosphere a 
certain quantity of matter in the form of rain-water, and also by 
its own direct absorption. Sulphates and chlorides, with smaller 
quantities of organic matter, ammonia, and nitrates, are thus 
regularly supplied. As a large portion of the rain-water is 
evaporated after falling on the soil, we should expect to find in 
the drain-water some of the constituents of the rain in increased 
proportion ; and this is actually the case when, as in the present 
instance, no crop is growing upon the soil. The large amount 
of nitrates found in drainage-water has, however, a source far 
more prolific than that furnished by rain. 
That nitrates are actually formed in surface soils, and fre- 
VOL. XVII. — S. S. 2 A 
