n. |
+----------------------+-----------------+------------+-------------+
| Silica and sand | 70.576 | 96.000 | 77.490 |
| Alumina | 1.050 | 0.500 | 9.490 |
| Oxide of iron | 0.252 | 2.000 | 5.800 |
| Oxide of manganese } | trace | { trace | 0.105 |
| Lime } | | { 0.001 | 0.866 |
| Magnesia | 0.012 } | | 0.728 |
| Potash } | } | | { trace |
| Soda } | trace } | trace | { |
| Phosphoric acid } | } | | 0.003 |
| Sulphuric acid } | } | | trace |
| Carbonic acid | ... | ... | 0.200 |
| Chlorine | trace | trace | trace |
| Humic acid | 11.910 | 0.200 | 0.732 |
| Insoluble humus | 16.200 | 1.299 | 0.200 |
| Water | ... | ... | 4.096 |
| |-----------------+------------|-------------|
| | 100.000 | 100.000 | 100.000 |
+----------------------+-----------------+------------+-------------+

The results contained in these analyses are peculiarly remarkable, for
they indicate the almost total absence of all those substances which the
plant requires. They must, however, be considered as in a great measure
exceptional cases, as it is but rarely that so large a number of
constituents is absent, and it is much more frequent to find the
deficiency restricted to one or two substances. They are illustrations
of barrenness dependent on different circumstances. The first shows the
unimportance of the organic matters of the soil, which are here
unusually abundant, without in any way counteracting the infertility
dependent on the absence of the other constituents. The second is that
of a nearly pure sand; and the third, though it contains a greater
number of the essential ingredients of the ash, is still rendered
unfruitful by the deficiency of alkalies, sulphuric acid, and chlorine.

An examination of the foregoing analyses indicates pretty clearly some
of the conditions of fertility of the soil, which must obviously
contain all the constituents of the plants destined to grow upon it. But
it by no means exh