Again, the well-known action of earthworms may be said to be a biological work; but the resulting aeration of the soil causes edaphic differences; and earthworms are absent from certain soils, such as peat.
The best soils are in the west section, where limestone clays or shell marls are common.
On rich loams and the alluvial soils of river-valleys, when well drained, the tree attains a large size, often rivalling the giant oaks of Europe; trunks of 3 or 4 ft.
Common throughout the northern and middle states and Canada, the red oak attains a large size only on good soils; the wood is of little value, being coarse and porous, but it is largely used for cask-staves; the bark is a valuable tanning material.
From the outer cortical myceliuni, again, branches pass through the epidermis and grow out in the soil, In stich cases the roots of the plants are usuall) found spreading in soils which contain a large amount of humus, or decaying vegetable matter.
The damping off of seedlingsand in saturated soils not only are the roots and root-hairs killed by asphyxiation, but the whole course of soil fermentation is altered, and it takes time to sweeten such by draining, because not only must the noxious bodies be gradually washed out and the lost salts restored, but the balance of suitable bacterial and fungal life must be restored.
Roots are often flattened, twisted and otherwise distorted by mechanical obstacles; stems by excess of food in rich soils, the attacks of minute parasites, overgrowth by climbing plants, &c. Leaves are especially apt to vary, and although the formation of crests, pitchers, puckers, &c., must be put down to the results of abnormal development, it is often difficult to draw the line between teratological and merely varietal phenomena.
Schimper used the term xerophytes to include plants which live in soils which are physiologically dry, and the term hygrophytes those which live in soils which are physiologically wet or damp. Schimper recognized that the two classes are connected by transitional forms, and that it is useless to attempt to give the matter a statistical basis.
~rphytes, grow in soils which contain an abundance of free imous compounds, and include plants which grow on fens and le .oors.
Psychrophytes.These include the plants which grow on the lv ild soils of subniveal and polar districts.
Hygrophytes.Plants which are sub-evergreen or evergreen but it scierophyllous, and which live in moist soils; e.g., Lastraea lix-mas, Poa pratensis, Carex ovalis, Plantago lanceolala, and ihillaea Millefolium.
Xerophytes.Plants which grow in very dry soils; e.g., most hens, Ammophila (Psamma) arenaria, Elymus arenarius, Anasis aretioides, Zilla macro ptera, Sedum acre, Bupleurum spinosum, rtemisia herba-alba, Zollikofferia arborescens.
Hydro-xerophytes (bog xerophytes) .Plants which live in ~t, peaty soils, and which possess aeration channels and xeroiilous leaves; e.g., Cladium Mariscus, Eriophorum angustifohium, if bus Chamaemorus, and Vaccinium Vitis-Idaea.
Many plants of peaty soils e sclerophylious.
As Chotts; and on the saline soils surrounding the Chotts, a salt marsh formation occurs, with species of Salicornia, some of which are undershrubs.
Halo phytes, or plants which live in saline soils, have xerophytic adaptations.
In England, the following species are confined or almost confined to calcareous soils: A splenium Ruta-muraria, Melica nutans, Carex digitata, Aceras anthropophora, Ophrys ap~ifera, Thalictrum minus, Helianthemum Chamaecislus, Viola hirta, Linum perenne, Geranium lucidum, Hippocrepis comosa, Potentiila verna, Viburnum Lantana, Galium asperum (= G.
It is sometimes said that lime acts as a poison on some plants and not on others, and sometimes that it is the physiological dryness of calcareous soils that is the important factor.
Again, acidic humus does not form in calcareous soils; and hence one does not expect to find plants characteristic of acidic peat or humus on calcareous soils.
- separates the " northern soils " from the " southern soils."
The " northern soils," which are glacial deposits more or less redistributed by water, are much less fertile as a rule, and consist of all possible varieties from a tough boulder clay to loose sand.
The hornbeam thrives well on stiff, clayey, moist soils, into which its roots penetrate deeply; on chalk or gravel it does not flourish.
The prevailing soils are sand and gravel loams, but other varieties are numerous, ranging from rich alluvial beds of extinct lakes, as in parts of Lyon and Esmeralda counties, to the strongly alkaline plains of the southern deserts.
The dwarf and pyramid trees, more usually planted in gardens, are obtained by grafting on the quince stock, the Portugal quince being the best; but this stock, from its surface-rooting habit, is most suitable for soils of a cold damp nature.
The pear-stock, having an inclination to send its roots down deeper into the soil, is the best for light dry soils, as the plants are not then so likely to suffer in dry seasons.
The introduction of new plants, which made it possible to dispense with the bare fallow, and still later the application to husbandry of scientific discoveries as to soils, plant constituents and manures, brought about a revolution in farming.
The work on agriculture' of Ibn-al-Awam, who lived in the 12th century A.D., treats of the varieties of soils, manuring, irrigation, ploughing, sowing, harvesting, stock, horticulture, arboriculture and plant diseases, and is a lasting record of their skill and industry.
Nitrate of soda, Peruvian guano and superphosphate of lime in the form of bones dissolved by sulphuric acid were now added to the list of manures, and the practice of analysing soils became more general.
Improvements in the plough, harrow and roller were introduced, adapting those implements to different soils and purposes.
The clay soils of England, Agricul- the latent fertility of which was to be brought into 187 since Y g I sis.
In 1891 excessively heavy autumn rains washed the arable soils to such an extent that the next season's corn crops were below average.
Incidentally there have been extensive sampling and analysing of soils, investigations into rainfall and the composition of drainage waters, inquiries into the amount of water transpired by plants, and experiments on the assimilation of free nitrogen.
Although barley is appropriately grown on lighter soils than wheat, good crops, of fair quality, may be grown on the heavier soils after another grain crop by the aid of artificial manures, provided that the land is sufficiently clean.
It seems obvious that the lighter and poorer soils would benefit more than the heavier or richer soils by the extended growth of leguminous crops.
In Canada and the United States this rational employment of a leguminous crop for ploughing in green is largely resorted to for the amelioration of worn-out wheat lands and other soils, the condition of which has been lowered to an unremunerative level by the repeated growth year after year of a cereal crop. The well-known paper of Lawes, Gilbert and Pugh (1861), " On the Sources of the Nitrogen of Vegetation,.
On heavy soils, however, the farmer cannot afford to curtail the time necessary for thorough cultivation of the land.
In the more southern parts of the island it often reaches a height of 90 ft., and specimens exist considerably above that size; but the young shoots are apt to be injured in severe winters, and the tree on light soils is also hurt by long droughts, so that it usually presents a ragged appearance; though, in the distance, the lofty top and horizontal boughs sometimes stand out in most picturesque relief above the rounded summits of the neighbouring trees.
In regions where climatic conditions are favourable, cotton grows more or less successfully on almost all kinds of soil; it can be grown on light sandy soils, loams, heavy clays and sandy " bottom " lands with varying success.
The most suitable soils are medium grades of loam.
Sandy soils are made thereby too dry and leachy, and it is a questionable proceeding to turn the heavy clays upon the top. Planters are, as a result, divided in opinion as to the wisdom of subsoiling.
In spite of the clean culture, good crops of cotton have been grown on some soils in the south for more than forty successive years.
The question of deep and shallow culture has been much discussed among planters without any conclusion applicable to all soils being reached.
The soils of Florida have sand as a common ingredient.'
Metallurgical operations, such as smelting, roasting, and refining, were scientifically investigated, and in some degree explained, by Georg Agricola and Carlo Biringuiccio; ceramics was studied by Bernard Palissy, who is also to be remembered as an early worker in agricultural chemistry, having made experiments on the effect of manures on soils and crops; while general technical chemistry was enriched by Johann Rudolf Glauber.1
Most of the rocks or soils composing its surface were formed as submarine deposits; the easternmost and southernmost parts are true river deposits.
On drier and higher soils are the persimmon, sassafras, red maple, elm, black haw, hawthorn, various oaks (in all 10 species occur), hickories and splendid forests of longleaf and loblolly yellow pine.
Soils are of four classes: calcareous-ferruginous, alluvial, argillous and silicious.
Deep residual clay soils derived from underlying limestones, and coloured red or black according to the predominance of oxides of iron or vegetable detritus, characterize the plains.
Tobacco is most generally cultivated on loose red soils, which are rich in clays and silicates; and sugar-cane preferably on the black and mulatto soils; but in general, contrary to prevalent suppositions, colour is no test of quality and not a very valuable guide in the setting of crops.
It is invariably present in soils, where compounds are formed by nitrifying bacteria.
63 of the Bureau of Soils, U.S. Department of Agriculture (Washington, 1910).
It is questionable whether it is not better, in cold soils and bleak situations, to abandon outdoor peach culture, and to cover the walls with a casing of glass, so that the trees may be under shelter during the uncongenial spring weather.
Sometimes the vegetation, shrubs, trees, &c., as characteristic of certain soils, may furnish evidence as to rock or minerals below.
But it is worthy of special attention that the mere chemical composition of agricultural and garden soils is, as a rule, the least important feature about them, popular opinion to the contrary notwithstanding.
Obviously no more than this is possible until physiologists are able to state much more precisely than at present what is the influence of common salt on the plants of salt-marshes, of the action of calcium carbonate on plants of calcareous soils, and of the action of humous compounds on plants of fens and peat moors.
All soils which are physically dry are also physiologically dry; and hence only the physiological dryness or wetness of soils need be considered in ecology.
Calcicole and Calcifuge Species.Plants which invariably inhabit calcareous soils are sometimes termed calcicoles; calcifuge species are those which are found rarely or never on such soils.