THE BKOADBALK WHEAT SOILS. 
123 
;*en, yields much more potash in its drainage — as much as the dunged 
Mat, which receives the greatest quantity of potash. 
The average quantities are in no case great, varying from 1 part of 
potash per million parts of water on plats 11 and 14, to 5.4 parts per 
million on plats 5 and 2; but the higher Quantities are nevertheless 
ugnifieant. Assuming an annual percolation of 10 inches of drainage 
water into the drainpipes or into the subsoil below 27 inches, the 
quantities found would probably represent as little as about 2i pounds 
3f potash pel* acre per annum in the case of plats 11 and 14, and as 
much as 12j pounds per acre from plat 5 (full mineral dressing with- 
>ut nitrogen) and from plat 2 (cont inuousU dunged). The difference 
between these two extremes would amount to . r ><><) pounds per acre in 
5fty years, hut it seems probable that, as the quantity of potassium 
kits has annually accumulated in the soil, the quantity of potash in 
the drainage waters will have become greater in later years on the 
potash-manured plats and on the continuously dunged plats. Dr. 
Voeleker's analyses, therefore, may he regarded as yielding, even as 
long ago as 1 86 7-1 869, evidence of appreciable descent of potash on 
the plat on which the applical ion <>f potassium salts had been excessive, 
iml where its utilization had been Least, owing to the absence of 
ii it rogenous manure, and also OB the continuously dunged plat. Fur- 
thermore, the analytical results of the subsoils of these plats down to 
i depth of 27 inches show a much Larger quantity of citric-acid-soluble 
potash 1 han do t hose <>f any of t he ot her plats, and 1 his seems to accord 
with the indications of the descent of some potash in the drainage 
water to even a lower depth. 
General Conclusions as to Potash. 
The general conclusions derived from the potash results, as summed 
up in the pap t recently laid before the Royal Society, 1 are to the 
effect that strong hydrochloric acid, as a solvent for potash in soil 
analysis, is again shown to be pract ically useless as a gauge of potash 
fertility, especially in soils containing an abundance of total potash 
in mineral combination as silicates, etc. No concordant results are 
obtainable except by working under the strictest arbitrary conditions, 
and the results, even when concordant, have little meaning apart 
from an independent knowledge of t he history of the soil. Wit Ii this 
knowledge they are interesting, but in its absence t hey are of little 
use except in ext reme cases. 
The results obtained by citric acid, however, are on the whole both 
instructive and consistent. They show that the largest accumulation 
of manurial potash, where applied in t he form of dung or of potassium 
salts, is in the surface soil; but that a large proportion is also found 
'Philosophical Transactions of the Royal Society [England], 1901, series B, vol. 
194, pp. 235-290. 
