Vízügyi Közlemények, 1936 (18. évfolyam)
Kivonatok, mellékletek - Kivonat a 4. számhoz
20 The water content of soil expressed in percentage of weight at which the two factors mentioned above are in equilibrium with the suction force of roots, is called „dead water" by Vageler. The dead water is almost identical with the term „withering point" used by the Anglo-Saxons. The soil water available for plants is the difference between the minimum water capacity (or water present) and the dead water. In soils in a natural state only the water volume corresponding to the minimum water capacity can be constantly stored. In deeper layers the capacity of storing water is also influenced by the volume of voids and the swelling. The movement of water in the soil is only in extreme cases governed by the permeability ; usually the capillary laws exert more influence. The capillary rise is an important feature of the different soils. The actual water content is dependent upon the kind of soil, the amount of rain, the vegetation and the season of year. These conditions are illustrated in two examples (Table X.). In addition the significance of Rotmistroff's intermediate dry layer is mentioned. The behaviour of the soil towards air is briefly discussed, and the significance of actual air capacity is indicated. The temperature of the soil depends upon the temperature of the air above it. The deeper the point of the soil profile observed, the smaller are the changes in the temperature found, and the more are the changes of air temperature retarded (sometimes 2 to 3 weeks). The profile of soil shows different horizons, and their formation is characteristic of the type of soil. In general, under conditions of an arid climate two, and under humid conditions three, characteristic strata can be distinguished. In the first case no washing out of salts and their accumulation in a deeper stratum can be established (climate of steppe, A — С soil). In the second case different constituents are washed out of stratum A and are amassed in the so-called accumulation horizon (B) ; below this comes stratum С (primary rock). In the Hungarian text pictures of different soil profiles are to be found (photo 1 ). The processes forming soils are chiefly influenced by climatic factors ; vegetation also plays an important part. Three main types may be distinguished : 1. Semiarid climate with dry hot summers and wet cold winters. Vegetation : grasses of steppe. Under these conditions the soils of steppe (Tshernoziom) are formed. If the soil is impermeable and poorly drained, different sorts of alkali soils are developed. 2. Where precipitates are abundant and uniformly distributed, and the temperature is moderate and cool, the so-called forest soils (podsol) are formed. 3. Under wet and warm climates the laterite soils are formed ; these are characterised by the accumulation of Fe and Al. The systematism of soils is given after the system of Prof. A. Sigmond. II. Examination of soils. The examination of the soil is made partly on the spot (taking profile), partly in the laboratory. When examining on the spot, the site has to be properly chosen. On flat lands places of equal elevation usually have the same type of soil, therefore the proper site for taking profile can be chosen without any difficulty. As a matter
