Soil science in 1881
This is an excerpt from a 1881 book, "The Household Cyclopedia". It is here because it shows the moment when we started to leave traditional soil management techniques dependent on natural processes, and began the use of chemical fertilizers.
We may take it for granted that every thinking practical mind, will admit it as proved, that there must be an exact adaptation and fitness between the condition of any given soil and the plants intended to be raised upon it; and, further, that if this mutual fitness does not naturally exist, a knowledge of its requirements will enable us to supply it artificially. The great difficulty is, to obtain this knowledge fully and accurately. It must be confessed that, at present, much is wanting to render it complete and directly available. Industrious observation and experiment may, hereafter, make it so; and thus give us a system of truly scientific agriculture.
A few statements only remain to be added to what has been said. The best natural soils are those where the materials have been derived from the breaking up and decomposition, not of one stratum or layer, but of many divided minutely by air and water, and minutely blended together: and in improving soils by artificial additions, the farmer cannot do better than imitate the processes of nature.
We have spoken of soils as consisting mostly of sand, lime, and clay, with certain saline and organic substances in smaller and varying proportions; but the examination of the ashes of plants shows that a fertile soil must of necessity contain an appreciable quantity of at least eleven different substances, which in most cases exist in greater or less relative abundance in the ash of cultivated plants; and of these the proportions are not by any means immaterial. In general, the soils which are made up of the most various materials are called alluvial; having been formed from the depositions of floods and rivers. Many of them are extremely fertile. Soils consist of two parts; of an organic part, which can readily be burned away when the surface-soil is heated to redness; and of an inorganic part, which remains fixed in the fire, consisting of earthy and saline substances from which, if carbonic acid or any elastic gas be present, it may, however, be driven by the heat. The organic part of soils is derived chiefly from the remains of vegetables and animals which have lived and died in and upon the soil, which have been spread over it by rivers and rains, or which have been added by the industry of man for the purposes of increased fertility. This organic part varies much in quantity, as well as quality, in different soils. In peaty soils it is very abundant, as well as in some rich, long cultivated lands. In general, it rarely amounts to one-fourth, or 25 per cent. even in our best arable lands. Good wheat soils contain often as little as eight parts in the hundred of organic animal or vegetable matter; oats and rye will grow in a soil containing only 1 1/2 per cent.; and barley when only two or three parts per cent. are present.
The inorganic portion of any given soil, again, is divisible into two portions; that part which is soluble in water, and thus easily taken up by plants, and a much more bulky portion which is insoluble.
Sir Humphrey Davy found the following to be the composition of a good productive soil. In every 9 parts, 8 consisted of siliceous sand; the remaining (one-ninth) part was composed, in 100 parts, as follows:
Carbonate of lime (chalk) 63 grains.
Pure silex 15 grains.
Pure alumina, or the earth of clay 11 grains.
Oxide (rust) of iron 3 grains.
Vegetable and other saline matter 5 grains.
Moisture and loss 3 grains.
Thus the whole amount of organic matter in this instance is only 1 part in 200, or one-half of one per cent.; a fact which, in itself, would demonstrate the fallacy of supposing that decomposed animal and vegetable matter in the soil form the exclusive supply to growing plants. In another instance, soil was taken from a field in Sussex, remarkable for its growth of flourishing oak trees. It consisted of 6 parts of sand, and 1 part of clay and finely-divided matter. One hundred grains of it yielded, in chemical language:-
Of silica (or silex) 54 grains.
Of alumina 28 grains.
Carbonate of lime 3 grains.
Oxide of iron 5 grains.
Vegetable matter in a state of decomposition 4 grains.
Moisture and loss 6 grains.
To wheat soils, the attention of the practical farmer will be most strongly directed. An excellent wheat soil from West Drayton, in England, yielded 3 parts in 5 of silicious sand; and the remaining two parts consisted of carbonate of lime, silex, alumina, and a minute proportion of decomposing animal and vegetable remains.
CHAPTER 1. AGRICULTURE Of these soils, the last was by far the most, and the first the least, coherent in texture. In all cases, the constituent parts of the soil which give tenacity and stiffness, are the finely-divided portions, and they possess this quality in proportion to the quantity of alumina (or earth of clay) they contain.
The varying power of soils to absorb and retain water from the air, is much connected with their fertility. This absorbent power is always greatest in the most fertile lands. Their productiveness is also much influenced by the nature of the subsoil on which they rest; for, when soils are situated immediately upon a bed of rook or stone, they dry sooner by the sun’s agency than when the subsoil is clay or marl.
A great deal more might be said upon other kindred points. But, as has been already remarked, agricultural science is, as yet, imperfect. It is a mistake for the practical farmer to contemn ”book farming,” as if it were something visionary or useless; while, on the other hand, the agricultural chemist and vegetable physiologist must submit all their inductions and conclusions to the test of careful and repeated trials. The one can seldom analyze soils, and the other can rarely attend to raising crops; so they must help each other, and, together, aid in advancing the oldest of human arts, and one of the most beautiful of the sciences - that of the earth’s culture.