122 
INVESTIGATIONS ON KOTHAMSTED SOILS. 
therefore possible that the estimate adopted may be more accurate for 
the dung recently used than for that of earlier years. There seems to be 
evidence here again that the potash of the dung travels downward with 
considerable facility, for, although the dunging has only been contin- 
ued for nine years, there is a great increase in the citric-aeid-soluble 
potash of the second 9 inches, and a considerable increase in that found 
in the third 9 inches. 
Potash in Drainage Waters. 
Reference has already been made to the results of analyses of the 
drainage waters of Broadbalk field made in 1867, 1868, and 1869 by the 
late Dr. Augustus Voelcker. 
Averaging the results of the potash determinations in the various 
samples analyzed during these years, we obtain the following figures: 
Table 66. — From analyses of Broadbalk field drainage icaters made by the late 
Dr. Augustus Voelcker, F. R. S. , 1866-18G9. 
[Parts per million.] 
Plat. 
Annual manuring. 
Average 
quantity 
of potash 
in drain- 
age water. 
3 and 4 Unmanured . 
10 Ammonium salts only . 
11 Ammonium salts and superphosphate. 
13 Ammonium salts, superphosphate, and sodium sulphate 
14 Ammonium salts, superphosphate, and magnesium sulphate. 
13 | Ammonium salts, superphosphate, and potassium sulphate .. 
Ammonium salts and full mineral dressing 
Full mineral dressing without nitrogen 
Farmyard manure 
1.7 
1.9 
1 
2.7 
1 
3.3 
2.9 
5.4 
5.4 
These results, although the samples were few, accord very well with 
what might be expected. The potash in the drainage water from plat 
1 1 (supplied with phosphates and nitrogen, but no potash) is less than 
in that from the unmanured plats, 3 and 4, or from plat 10, which 
received only ammonium salts, the utilization by the crops being, of 
course, greater on plat 11 in presence of an abundant supply of phos- 
phates and nitrogen. 
Plat 12, supplied in its earlier history with potash, and, in virtue of 
this (and probably also of the solvent action of the sodium salts), 
showing, in the 1865 soil samples, more citric-acid-sol uble potash than 
plat 11, also yields more potash in its drainage water, and it also 
yields more thai) plat 14, to which magnesium salts were applied, 
which is again in accord with the citric-acid results. 
Plat L3, well supplied with potash, shows decidedly more potash in 
iis drainage water than plat 7, which, while also liberally supplied 
with potash, gels in addition, sodium and magnesium salts, and gives 
in consequence a greater crop, utilizing somewhat more potash. 
Plat 5, getting a fuller supply of minerals than plat 13, but no nitro- 
