A vegetation pot experiment was established to explore the effect of two doses of nitrogen (0.6 and 0.9 gN in the form of ammonium sulphate) and two doses of sulphur (20.6 and 30.6 mg/kg of soil) on the yields and quality of spinach and pepper in comparison with a natural level (7.85 mg/kg). The results of the experiments confirmed that the application of sulphur by means of (NH₄)₂SO₄ in combination with nitrogen had a positive effect on yields and also on the quality of the vegetables. In the sulphur-free variants of spinach the effect was statistically significant and also when the levels of S in the soil were higher. Lower doses of nitrogen under increased levels of sulphur increased the yields statistically significantly (on average by 47%) and the sulphur concentration in the plants increased. The N:S ratio became narrower in proportion with the level of sulphur, particularly under a lower N level. The nitrate content in spinach corresponded with the applied dose of nitrogen and the nitrogen concentration. The sulphur level did not influence the content of C vitamin, but had a positive effect on the content of the essential amino acids cysteine and methionine. A mean level of S₁ in combination with a N₁ dose significantly increased pepper yields, narrowed the N:S ratio and was reflected in dry matter production per 1 g of N. The highest pepper yields were achieved with a dose of S₁, which resulted in the highest dry matter production in the fruit per1 g of N under both levels of N. At the same time increasing the sulphur level reduced the content of nitrate and increased the level of cysteine from 0.11 to 0.305 g/kg.

An inductively coupled plasma mass spectrometry (ICP/MS) method was used for the evaluation of thallium transfer from naturally (pedogeochemically) and artificially contaminated soils into rape. Two sets of three different types of top soils (heavy, medium, and light) were used for pot experiments. The first set was collected from areas with high levels of pedogeochemical thallium (0.3, 1.5, and 3.3 mg kg(-1) DM). The second set of three soils with naturally low content of thallium was artificially contaminated with thallium sulfate to achieve five levels of contamination (0, 0.4, 2, 4, and 6 mg kg(-1) DM Tl). The soil samples and the samples of winter and spring rape (straw, seeds) from both sets were collected and analyzed. Plant and soil samples from fields were collected at 42 selected sites situated in South Bohemia and in Czech-Moravian Highlands where higher pedogeochemical content of thallium was expected. More intensive transport (better availability) of Tl was observed in the case of artificially contaminated soils. The physicochemical form and the total content of Tl in soil were found to be the main factors influencing its uptake by plants. The concentration of Tl in rapeseeds in the field samplings was mostly 45% of its content in the particular soil. Nevertheless the uptake of Tl from soils with naturally high pedogeochemical content can be high enough to seriously endanger food chains. These findings are very important because of the high toxicity of Tl and the absence of threshold limits for Tl in soils, agricultural products, feedstuffs, and foodstuffs in most countries including the Czech Republic.

Thallium transfer from naturally (pedogeochemically) contaminated soils into vegetables was studied. Three different types of top-soil (heavy, medium, and light) were used for pot experiments. The soils were collected from areas with low, medium, and high levels of pedogeochemical thallium (0.3, 1.5 and 3.3 mg kg(-1)). The samples of vegetables were collected and analysed. The total content of thallium in soil and the type of soil (heavy, medium and light), plant species and plant variety were found to be the main factors influencing thallium uptake by plants. The uptake of thallium from soils with naturally high pedogeochemical content of this element can be high enough to seriously endanger the food chain. These findings are very important because of the high toxicity of thallium and the absence of threshold limits for thallium in soils, agricultural products, feedstuffs and foodstuffs in most countries, including the Czech Republic.

An important goal of sustainable agriculture is to maintain soil quality. Soil aggregation, which can serve as a measure of soil quality, plays an important role in maintaining soil structure, fertility, and stability. The process of soil aggregation can be affected through impacts on biotic and abiotic factors. Here, we tested whether soil management involving application of organic and mineral fertilizers could significantly improve soil aggregation and if variation among differently fertilized soils could be specifically attributed to a particular biotic and/or abiotic soil parameter. In a field experiment within Central Europe, we assessed stability of 1–2 mm soil aggregates together with other parameters of soil samples from differently fertilized soils. Application of compost and digestates increased stability of soil aggregates. Most of the variation in soil aggregation caused by different fertilizers was associated with soil organic carbon lability, occurrence of aromatic functional groups, and variations in abundance of eubacteria, total glomalins, concentrations of total S, N, C, and hot water extractable C. In summary, we have shown that application of compost and digestates improves stability of soil aggregates and that this is accompanied by increased soil fertility, decomposition resistance, and abundance of total glomalins and eubacteria. These probably play significant roles in increasing stability of soil aggregates.