Krzysztof Otremba, Mirosława Gilewska, Wojciech Owczarzak
Uniwersytet Przyrodniczy, Poznań
An attempt was made in this investigation to determine the impact of the following four systems of soil agricultural use: not subjected to any reclamation treatment, fodder-cereal reclamation treatment, rape-cereal reclamation treatment and the so-called “conservation” treatment (permanent lucerne) on the properties of soils developing from post-mining grounds. A particular attention was paid to the properties of the humus layer of the developing soils, among them, their texture which belongs to the most important soil diagnostic features. Experiments were carried out in 2010 on the experimental field of the Department of Soil Science and Reclamation of the University of Life Sciences in Poznań. A combination without mineral fertilisation (0NPK) was established on each of the analysed use systems. In the case of the fodder-cereal and rape-cereal systems, additionally, two levels of mineral fertilisation: 1NPK – in rape-cereal system (rape: 200 kg N, 70 kg P2O5, 90 kg K2O; wheat: 160 kg N, 40 kg P2O5, 80 kg K2O) and in fodder- cereal (lucerne: 170 kg N, 60 kg P2O5, 150 kg K2O; wheat: 160 kg N, 40 kg P2O5, 80 kg K2O) and 2NPK were applied. The control was post-mining ground which was not subjected to any reclamation treatment. The evaluation of changes in the selected, most important soil structure parameters was based on the original methodological solution elaborated at the Department of Soil Science and Reclamation of the University of Life Sciences in Poznań in which the basic element is a regular soil aggregate of 1 cm3 volume. The following parameters were determined for such aggregates cut out from two depths of the humus layer (7 and 15 cm): dynamic water resistance (SW), static water resistance (SW), secondary aggregation after dynamic and static water action, time of capillary rise (Tkmin), capillary minimal (Vkmin) and maximal (Vkmax) water capacity and compression strength (Rc). The above-mentioned properties were determined in 5 replications. Using methods commonly employed in soil science, the following parameters were determined: texture composition, solid phase density, bulk density and porosity, hygroscopic capacity and maximal hygroscopic capacity as well as soil reaction and carbonate, carbon and nitrogen contents. Reclamation treatments applied in the course of the past 32 years and soil-forming processes taking place under their influence led to distinct changes in the morphological structure of the examined profiles, primarily, in their surface layer. The smallest morphological changes were observed in the profile sampled from the plot with long-term lucerne cultivation (so-called “conservation”). The profiles representing the fodder-cereal use system exhibited a more advanced stadium of soil-forming processes. Their humus layer was more distinctive, with dark colour, its thickness ranged from 20 to 28 cm corresponding to the depth of the performed ploughing. Identical features and better homogeneity were observed in the case of the humus horizon developed in the rape-cereal system of agricultural use, although certain differences were recorded in profile morphology depending on the level of the applied mineral fertilisation (1NPK and 2NPK). Post-mining ground which was not subjected to any reclamation treatment was found to contain the smallest quantities of organic material – carbon and nitrogen (2.65-2.84 g·kg-1). The amount of oxidisable carbon in the fodder-cereal system of agricultural use was 2.5 to 3 times higher (6.45-8.82 g·kg-1) than in the untreated post-mining ground irrespective of the level of mineral fertilisation. On the other hand, the amount of carbon was more varied in the rape-cereal system of use. In the case of absence of fertilisation (0NPK), this quantity was by about 50% higher in comparison with the post-mining ground and amounted to 3.1 g.kg-1. Elevated fertilisation with 1NPK and 2NPK doses increased levels of carbon to values similar as in the fodder-cereal system. The highest quantity of carbon of about 12 g.kg-1 was recorded in the humus horizon developed on the surface representing permanent lucerne (so-called “conservation”). A distinct variability was also observed in the physical properties of soils from the examined systems of agricultural use. Untreated post-mining grounds were characterised by high bulk density (1.97–2.02 Mg·m-3) and, consequently, by low general porosity (23.6 to 25.3%). In the fodder-cereal use system, soil density was found to be by about 0.30 Mg·m-3 lower and porosity – by about 10% higher. In the case of the rape-cereal system of agricultural use, soil density was only by about 0.1 Mg·m-3 higher and general porosity – by about 5% lower in comparison with the fodder-cereal system. Bulk density and general porosity in the so-called “conservation” system of use amounted to 1.35–1.51 Mg·m-3 and 42.8–48.9%, respectively, in other words, exhibited the most advantageous values of these features from the point of view of agricultural usage. Recapitulating, it should be emphasised that widely distinguished two soil-forming factors, namely: time and human activity begin to play a dominant role in the formation of soils, especially in areas which undergo large industrial geomechanical transformations mainly as a result of open-cast mining of different minerals.
rolnicze użytkowania; właściwości gleby
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