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II.-TABLE OF THE AUSTRALIAN SOILS OF THE LOWEST PRODUCTIVE POWER.
1.40 | 10.00
2.00 70:10 16.20 0.20 2.50
1.30 Traces. Traces.
The facts which the two preceding tables furnish, bearing on the question of the productiveness of soils, are,—
1st. That both kinds of soils, that is the fertile and the sterile, aborb, on an average, nearly the same amount of solar heat, but that they differ in their respective power of terrestrial radiation: the fertile soil emits, through radiation, an amount which is two thirds less than that yielded by the sterile soil.
2ndly. That their respective capacities for absorbing atmospheric moisture are different also ; the fertile soil absorbing more than double the quantity absorbed by the sterile soil.
3dly. That their solubility in hydrochloric acid is not equal; the fertile soil containing, in 100 parts, 30 parts of soluble matter, while the sterile soils contain but 8 per cent.
4thly. That the difference in the amount of vegetable and animal matter, in the two kinds of soils, is likewise great; the fertile possessing nearly three times as much of these ingredients as the sterile.
5thly. That the mineral constituents of each kind of soil, considered apart from the vegetable matter, the hygrometric water, and the loss in the analysis, and expressed in their atomic weight, are, in the
High Productive Soils.
6.25 = 0·020 .
1.00 - 0.87
the Numbers. - - 30 - - 5 • • 1
The atomic weight of their respective constituents thus shows, that the fertile soils differ from the sterile not only in the number of constituents, but in the proportion in which they are found to be combined.
From the above, the following conclusions are deduced:
That absorption and emission of solar heat, in various proportions, constitute a physical property in soils, which property is connected with their productiveness; and that, as far as regards Australian soils, whenever, according to the averages of the tables, the amount of aborption is to that of emission as 5•76:1, this property of the soil is highly favourable to agriculture; and whenever it is as 2:34:1, it is highly injurious to it.
That the productiveness of a soil is influenced by a property, which the soil is found to possess, of absorbing atmospheric moisture; and that, as regards the Australian soils, whenever this property manifests itself in an amount above the average of that of the sterile soils, i. e. + 3.6, it is beneficial to agriculture, and when below, it is detrimental to it.
That the quantity of the soluble constituents in a soil determines its productive power; and that, as respects Australia, those of its soils which have 30 per cent. of soluble constituents are the best adapted to agriculture, and that those of which the soluble part is but 8 per cent. are the least fit for it.
That a certain amount of vegetable matter in
Australian soils is indispensable to their productiveness ; 15 per cent. appearing highly propitious, and 5 per cent. highly injurious to it; and that it further appears evident, from synthetic experiments, that the amount of vegetable fibre in a soil regulates not only the proportion between its absorption and emission of heat, but also, in a great measure, its power of absorbing atmospheric moisture.
Lastly, that, as regards the mineral ingredients of the Australian soils, it seems very probable that a combination of one atom of the peroxide of iron with one of the sulphate of lime, five of the carbonate of lime, five of alumina, and thirty of silica, constitutes a fertile soil; and that a combination of one atom of the peroxide with two of carbonate of lime, three of alumina, and twenty-six of silica, constitutes a sterile one,
From the preceding survey of farms and farming, and from the examination of the different productive and unproductive soils, it is obvious that, great as are the number of actual improvements in the two colonies, the list of those which remain to be introduced must be still greater.
Hitherto, the colonial farmer has, generally speaking, attended to but one part of the great farming principle of aiming to produce the most at the least expense. That part which relates to combining both economy of capital and the highest profit with the continual increase of the productive power of the soil, has been lost sight of.
Innumerable examples of the evil consequences attending this neglect of farmers are on record; and many of the best known soils of the globe may be pointed out, as having at one time enriched their