The relationships among soil microbial biomass, pH and available of heavy metal fractions were evaluated in longterm contaminated soils during an incubation experiment with the amendment of zeolite (natural clinoptilolite) and the subsequent addition of glucose. The values of pH a�er the addition of glucose decreased during the first day of incubation approximately at about one unit and corresponded with the maximum increase of microbial biomass. The available heavy metal contents extracted by H 2 O, 1 mol/l NH 4 NO 3 and 0.005 mol/l DTPA increased during the first two days of incubation. Only a few significant relationships were found between the available metal contents and pH or microbial biomass. This fact could be ascribed to the different dynamics of the microbial biomass, pH and metal availability a�er glucose addition, when the highest metal contents during the incubation were usually reached one day later in respect to the greatest changes of pH and microbial activity. In comparison to soils without zeolite addition, the variants with natural clinoptilolite showed lower heavy metal contents in all used extractants with the exception of Cd which in H 2 O extracts tended to increase.

The effect of organic, mineral and combined organic and mineral fertilization of soils on the winter wheat yields and nutrient contents in soils was evaluated in long-term field experiments. Two sites with different soil characteristics were evaluated -Lukavec u Pacova (cambisol) and Ivanovice na Hané (degraded chernozem). The type of fertilization influenced wheat yields. Nutrient uptake by winter wheat was higher under nitrogen (N) fertilization, which resulted in a negative balance of phosphorus (P) and potassium (K) and to a decrease of nutrient contents in the more fertile soils at Ivanovice na Hané. Two soil tests (Mehlich 3 method and NH 4 -acetate method) were used to determine P and K availability. The mineral nitrogen fertilization negatively and significantly affected NH 4 -acetate extractable concentrations of nutrients in the soils and these were lower in comparison with concentrations of P and K determined by Mehlich 3 method. Relative availability of P in alkaline soils from Ivanovice treated with mineral N increased while the soil pH decreased.

The boron (B) availability and uptake were studied in relation to different phosphorus rates applied into soils in a three-year field experiment (2015–2017). The experiment was carried out at the experimental station at Humpolec (Bohemian-Moravian Highlands, Czech Republic). Three rates of phosphorus (20-40-80 kg P/ha) were applied as triple superphosphate. The crop rotation was spring barley-winter oilseed rape-winter wheat. No systematic fertilization with B was used and the response of natural boron soil content to the different phosphorus supply was studied. The crop yields, B content in plants, B-uptake, and content of B (extracted by Mehlich 3 and NH₄ acetate methods) were determined. Spring barley and winter wheat B uptake was about one order of magnitude lower in comparison with oilseed rape. Significant differences in B content in soils, in crop tissues and B-uptake, were found mainly under higher phosphorus doses (40 and 80 kg P/ha). NH₄ acetate method showed better correlations between P and B contents in soils than Mehlich 3 method from the second experimental year. The P-fertilization may affect negatively the B-uptake by plants, particularly if the highly nutrient demanding crop is grown.

The aim of the present paper was to determine the impact of gypsum treatment of soils on initial growth and nutrient uptake by spring barley. Topsoil from 36 different farmed fields was used for the research. Two variants were established for each soil: control -without gypsum application, and response variant -with the application of 3.3 ppm CaSO 4 .2 H 2 O. Barley was grown on these soils for 21 days in a plant growth chamber under controlled conditions of cultivation. Concentrations of nutrients (N, NO 3 -, P, S, K, Mg, Ca, Na, Fe, Mn, Zn, Cu, B and Mo)were determined in the yield of barley shoot biomass. Paired t-test was used for the evaluation of results. After the gypsum treatment the yield of barley shoot biomass was significantly higher (by 15% on average) and nitrogen utilisation was better on all soils. The concentration of sulphur increased five times on average and Ca concentration increased by 22%. Significant increases were measured in Mg, Mn and Cu. Insignificant differences were recorded in K, Na, Fe and Zn. The uptake of anion nutrients (P, B and Mo) was influenced significantly. The concentration of P and Mo decreased on average by 28% and 31%, respectively. B concentration was higher by 10% on average.

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