Vízügyi Közlemények, 1936 (18. évfolyam)
Kivonatok, mellékletek - Kivonat a 4. számhoz
18 of the Tamarix are only shrubs. On damp mild alkali lands the Salix alba (TV. 64), Populus alba, Populus canadensis, Praxinus excelsior (IV. 79), and Ulmus glabra (IV. 69) are suitable as trees : while on dry alkali lands the Ailanthus glandulosa (IV. 72), Sophora japonica (IV. 70), Koelreuteria paniculata (IV. 74), Gleditschia triacanthos, Elaeagnus angustifolia (IV. 78), and Pirus piraster are to be recommended. Of the numerous varieties of oak, the Quercus lanuginosa (IV. 66), Quercus cerris (IV. 65), Quercus robur (IV. 67), and especially the Quercus tardissima are good for the afforestation of mild alkali lands. Of the different sorts of shrubs, the Lycium halimifolium, Syringa vulgaris, 'Crataegus monogyna, Sambucus nigra, Ribes aureum and Prunus spinosa are mostly to be found on alkali lands ; while among fruit trees the Prunus armeniaca and Prunus communis can best endure a moderate alkalinity of the soil. The object of this description is to familiarise civil engineers working at reclaiming alkali soils with plants which give useful indications of the degree of alkalinity, and to suggest the measures to be taken. II. A SHORT SUMMARY OF THE SCIENCE OF SOIL. By A. ENDRÉDY. (Pages 4G7— 540.) I. General Knowledge. Definition. Soil is the upper layer of the earth surface on or in which plants live or may live. The idea of soil comprises not only the top layer, mostly darkcoloured with humus, but the whole series of strata created or modified by soilforming processes and reaching down to the primary rocks (soil profile). Petrographically the soil is a sedimentary rock ; geologically it belongs mostly to the Holocene formations, but there are also soils of older origin, the so-called residual soils. In the wider sense of the word, the soil is a living, dynamic system. Composition of soil. The soil as a polydisperse system may be characterised by its solid, liquid and gaseous constituents. For classifying the types of soils, only the proportions of solid particles, the so-called mechanical composition, can be used. Atterberg proposes that soils should be divided into four or five groups according to the size of particles. On this basis sandy, loamy, clayey and stony-gravelly soils are distinguished. The conditions of formation of soils are to a certain extent revealed in the mechanical composition. Great differences may exist between the natural and the dispersed conditions, which characterise the stability of coagulation processes in the undisturbed soil. In the mechanical analysis, therefore, the method by which the soil has been dispersed must always be noted (Tables I and II). The mechanical analysis only gives information about the proportion of grain sizes, but it does not deal with the material of the particles. The grains may consist of inorganic and organic matter.
