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A CONTRIBUTION TO THE STUDY AND THE SIGNIFICANCE OF THE CHANGES IN THE CONSISTENCE AND VOLUME IN HEAVY, VERTIC SOILS OF THE PILOT FARM JEŽEVO
Zoltan Racz
; Poljoprivredni fakultet u Zagrebu
Sažetak
The Pilot Farm Ježevo was established in accordance with the Project UNDP for Yugoslavia, with the aim of its future growing into an experimental station for heavy hydromorphic soils, which would have wider, international significance (ILACO, 1972). Pedological investigations under the above title were carried out within the theme „Investigations of complex agrotechnical practices on heavy soils in the Upper Save Valley - the Ježevo locality“. Their purpose was to determine: a) the basic parameters and changes in the consistence, depending on the moisture dynamics in the soil, b) potential and actual changes in volume, total porosity and air content in the soil, and c) their significance for the agriotechnical practice and, generally, for the exploitation of hydroarneliorated soils of the Farm. The investigations were carried out on the production plots 8, 19 and 17 with pipe drainage of various intensity (spaces 15, 20 and 25 m, depths 1.1 and 1.25 m). According to the marked oder of production plots, they are former: noncalcareous, vertic, humous, amphigley soils, mineral variety of amphigley soils, also noncalcareous and vertic, and - browned meadow soils. Standard methods (JDPZ,1971) were used in the field and laboratory experiments, as well as more recent experiences of foreign authors (See Literature), The results are presented in Tables 1-5 and Graph 1. The lay-out of the Farm is shown in Figure 1. The following conclusions were drawn: 1. Heavy vertic soils of the Pilot Farm Ježevo have very unfavourable mechanical properties. In addition to other characteristics of plasticity, this is also confirmed by the unfavourable relation between the lower plasticity limit and the field water capacity (0.8 - 0.9). Further more, by the low values of the consistence index (lower than 0.25 and 0.25 - 0.50) with the corresponding liquid state or very soft plasticity in the course of spring (Table 2). 2. In the described conditions to soil consistence, mechanical tillage is practically unfeasible. This is also the main reason for the delayed seedbed preparation and sowing of maize in spring on most arable areas of ahe Farm. 3. Other physical properties of these soils are also unfavourable due to greater changes in the volume, depending on the moisture dynamics in the soil. They are characterised by high values of the coefficient of linear extensibility (0.12 - 0.22) and swelling (N %). For instance, the swelling values in spring amount to 51 - 113, and to 39 - 50 % in autumn (Table 4). 4. The side effects are complex changes in the porosity and soil structure, that is in the distribution of macro- and micro- pores, with an unfavourable effect upon the water - air relationship in the soil (Graph 1). Spring is the critical period again, when the current air content amounts to only 0.1 - 2.5 vol. % (Table 5). 5. Finally, in the author's opinion, the described conditions require: - either corrections of the planned crop rotation (maizewinter wheat - clover-grass mixtures), - or further intensification of particular detailed drainage systems at the Farm.
Ključne riječi
Hrčak ID:
165105
URI
Datum izdavanja:
30.5.1974.
Posjeta: 594 *