For characterization of the ability of crops to reflect changing soil properties after the addition of ameliorative materials into the soil both pot and rhizobox experiments were provided. In the pot experiment, the influence of the addition of lime and limestone into contaminated Cambisol containing 7.14 mg Cd/kg, 2174 mg Pb/kg, and 270 mg Zn/kg on element availability for spring wheat was tested. The ameliorative materials were added into the pots containing 5 kg of soil in amount of 3 g CaO, and 5.36 g CaCO 3 per kg of the soil. Soil pH reached up to 7.3 in lime treatments compared to 5.7 in control soil. Mobile portion of soil elements (0.01 mol/l CaCl 2 extractable) dropped by 80% for Zn, 50% for Cd, and 20% for Pb, respectively. In both straw and grains of wheat reduced content of elements was observed in limed pots compared to the control ones. For a detailed characterization of the influence of root exudates on the strength of developed complexes in comparison with the bulk soil, short-term rhizobox experiment was set up under identical soil and lime treatments. Generally, the results of rhizobox experiment confirmed the findings from the pot experiment discussed above. Content of elements in shoots and roots of wheat dropped mainly in the case of Cd and Pb. Soil mobile portion of all three tested elements introduced clear depletion curve in control treatment, both limed treatments showed high stability of element complexes almost unaffected by wheat roots.

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In the current study, pre-composting and subsequent vermicomposting of separated digestate (also called separated biogas plant slurry) were verified to improve its properties for use as a soil conditioner. Increasing the proportion of straw in combination with separated digestate had a positive effect on reducing both weight and volume during vermicomposting. The pH value decreased and was found to be between 7.3 and 7.7 in the final vermicomposts. Due to a loss in organic matter, the total content of macro-elements increased at the end of vermicomposting with the exception of calcium. Similarly, the available contents of phosphorus and potassium increased, which was positive in terms of the use of vermicompost for agricultural purposes. After 5 months of vermicomposting, the earthworm biomass increased from 282 to 896 % depending on the treatment. The best results were achieved during the vermicomposting of a mixture of straw (25 vol %) with separated digestate (75 vol %).

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