22 On the Rain and Drainage - Waters at Rothamsted. 
The superphosphate and the sulphates of potassium, sodium, 
and magnesium, applied to Plot 5, considerably increase the 
contents of the drainage-water, the dissolved matter rising to 
329"8 per million. The sulphate of calcium present in the 
superphosphate, and the sulphate of sodium, are the chief con- 
stituents of the manure which appear in the drainage-water : 
the sulphates of potassium and magnesium also react on the lime 
contained in the soil, and furnish a further supply of sulphate of 
calcium to the water. 
When ammonium-salts are applied to the land, the quantity 
of matter removed in the drainage-water is much increased ; 
thus in the water from Plot 10, receiving 400 lbs. of ammonium- 
salts alone, the dissolved matter reaches 441"8 per million. 
When ammonium-salts are added to the mixed mineral manure, 
the solid contents of the drainage-waters rises in proportion to 
the quantity of these salts applied. Thus in the drainage-waters 
from Plots 6, 7 and 8, to which 200, 400 and 600 lbs. of ammo- 
nium-salts are applied, the mean proportion of total solid matter 
is respectively 450'3, 542"4, and615'l per million. 
The solid matter removed from the soil by the agency of the 
ammonium-salts consists chiefly of sulphate, chloride, and ni- 
trate of calcium. Probably the whole of the sulphuric acid and 
chlorine contained in the ammonium-salts unites with lime and 
magnesia in the soil ; the resulting salts being soluble, they 
will be removed, to a greater or less extent, in the drainage- 
water as soon as a sufficient rainfall occurs. The 400 lbs. of 
ammonium-salts would be able to remove annually from the 
soil in this way about 172 lbs. of lime.* The actual loss of 
lime would, however, be somewhat less, as a part of the sulphuric 
acid and chlorine of the ammonium-salts would be retained by 
the crop. Loss of lime will also occur as nitrate of calcium. 
Ammonia is speedily oxidised to nitric acid in the soil ; this 
acid combines with lime and magnesia in the soil, and 
nitrates appear in the drainage-water. Supposing that the 
whole of the ammonia were converted into nitric acid, and that 
the resulting nitrates were entirely lost by drainage, the soil 
would suffer a further loss of about 172 lbs. of lime for 400 lbs. 
of ammonium-salts applied. On a cropped soil, of course, the 
loss on this score would be greatly diminished, as the crop would 
assimilate a large part of the nitrates formed. The action of 
ammonium-salts in impoverishing a soil of lime and magnesia 
* This amount of lime would of course not be removed in tlic first 5-car of the 
application of ammonium-salts, unless the drainage were especially excessive. 
As, however, the soil became yearly richer in Eoluble calcium-salts, the drainage- 
water would increase in strength, until at last the loss by drainage balanced the 
annual receipt. 
