The research was based on a pot experiment, in which the response of eight species of crops to soil contamination with fluorine was investigated. In parallel, some inactivating substances were tested in terms of their potential use for the neutralization of the harmful influence of fluorine on plants. The response of crops to soil contamination with fluorine was assessed according to the volume of biomass produced by aerial organs and roots as well as their content of N-total, N-protein, and N-NO₃ ⁻. The following crops were tested: maize, yellow lupine, winter oilseed rape, spring triticale, narrow-leaf lupine, black radish, phacelia, and lucerne. In most cases, soil pollution with fluorine stimulated the volume of biomass produced by the plants. The exceptions included grain and straw of spring triticale, maize roots, and aerial parts of lucerne, where the volume of harvested biomass was smaller in treatments with fluorine-polluted soil. Among the eight plant species, lucerne was most sensitive to the pollution despite smaller doses of fluorine in treatments with this plant. The other species were more tolerant to elevated concentrations of fluorine in soil. In most of the tested plants, the analyzed organs contained more total nitrogen, especially aerial organs and roots of black radish, grain and straw of spring triticale, and aerial biomass of lucerne. A decrease in the total nitrogen content due to soil contamination with fluorine was detected only in the aerial mass of yellow lupine. With respect to protein nitrogen, its increase in response to fluorine as a soil pollutant was found in grain of spring triticale and roots of black radish, whereas the aerial biomass of winter oilseed rape contained less of this nutrient. Among the analyzed neutralizing substances, lime most effectively alleviated the negative effect of soil pollution with fluorine. The second most effective substance was loam, while charcoal was the least effective in this respect. Our results showed the effect of soil contamination with fluorine on the yield and chemical composition of fluorine depended on the species and organ of a tested plant, on the rate of the xenobotic element and on the substance added to soil in order to neutralize fluorine.

In the context of a circular economy, special attention should be paid to the rational management of biodegradable waste. Currently, a potentially valuable waste material, rich in ingredients available to plants, is digestate, obtained as a by-product in agricultural biogas plants. The presented study aimed to determine the impact of digestate (DIG) from an agricultural biogas plant on soil reaction (pH), electrical conductivity (EC), sorption properties (SBC, HAC, CEC, BS), and chemical composition of soil. The research was based on a pot experiment in which increasing doses of liquid (LD) and solid (SD) forms of DIG were used in corn cultivation, balanced in terms of the amount of N introduced into the soil. The composition of DIG varied and depended on the LD or SD form. The LD was characterized by a lower pH value and higher EC compared to the SD form. The LD contained much less TC, fewer macroelements, and fewer trace elements. The application of LD significantly increased in the soil the content of TC, N_tot, available K, P, Fe, and Mn, and exchangeable cations K⁺. The SD significantly increased the content of available P, Mg, and Mn and exchangeable cations Ca²⁺ and Mg²⁺ in the soil. Both forms of digestate increased the total content of heavy metals (Cu, Cr, Pb, and Ni) in the soil. However, they did not pose a threat to the environment concerning their legally permissible levels.

In recent years, there has been growing interest in using wood biomass for energy production, which has led to an increase in post-processing waste in the form of wood biomass ash (WBA). Due to the rich composition of WBA, its fertilising potential should be considered. In the conducted studies, WBA was used both alone and in combination with digestate (DG). The WBA was obtained from the Municipal Heat Energy Company and the DG from the Agricultural Biogas Plant in the form of unseparated liquid digestate (ULD), separated solid digestate (SSD) and separated liquid digestate (SLD). The studies included four series: (1) WBA, (2) WBA + ULD, (3) WBA + SSD and (4) WBA + SLD. In each series, WBA was introduced in three increasing doses (0.5, 1.0 and 1.5, expressed in hydrolytic acidity units (HACs) and determined based on the general alkalinity of the material). The digestates (DGs) were applied in fixed doses, which were balanced with respect to the nitrogen introduced into the soil. The test plant was the maize (Zea mays L.) variety Garantio, which was grown in a vegetation hall. The obtained results indicate that the combined use of WBA and DGs (especially ULD and SLD) had a positive effect on the plant height, leaf greenness index (SPAD), and thus, maize yield and dry matter content. In the series with DG addition, the maize yield ranged from 615.5 g (WBA + SSD) to 729.6 g pot⁻¹ (WBA + SLD), which was 28–52% higher than in the series with WBA alone. In turn, the application of increasing doses of WBA alone did not significantly affect the biomass yield but significantly increased the content of N (34%), K (60%), Mg (56%), Ca (60%) and Na (4%). In the series with WBA and DGs, the increase in the content of the above-mentioned macronutrients depended on the type of DG and the dose of WBA. The exception among the macronutrients was P, whose content generally decreased (by 4–23%) with an increasing WBA dose, regardless of the test series. The most favourable results in terms of the chemical composition, excluding the P content, were observed following the combined application of WBA and liquid forms of DG (ULD and SLD).

Pollution of the natural environment with fluorine compounds makes the continuous monitoring of the content of this element necessary, not only in the air, water and soil, but also in food. A high level of fluorine contamination of soils can affect quality of the obtained yields, affecting the amino acid composition of protein. It often becomes a cause of reducing nutrition and feed value of agricultural yields. In the undertaken studies, the influence of fluorine application to the soil on the amino acid content in proteins accumulated in the above-ground parts (aerial) of Zea mays L. and Lupinus luteus L. was studied. The lowest and medium doses of fluorine had a significant positive effect on the content of exogenous and endogenous amino acids in the protein of the aerial mass of maize, for which the increase of sum of all amino acids was 7% and 8%, respectively, in relation to controls. The above-ground parts of yellow lupine were characterised by a much higher content of the tested amino acids than maize. The subsequent influence of soil contamination with fluorine on the amino acid content in yellow lupine did not have the same effect as in the main plant, and the influence of fluorine was somewhat limited. With respect to yellow lupine, it was demonstrated that the lowest fluorine dose (100 mg F kg⁻¹ of soil), did not have a beneficial influence on the sum of all amino acids. The medium and highest doses of fluorine depressed in a small degree the content of the sum of these compounds in the dry mass of yellow lupine.

Nowadays, waste that can be used for environmental purposes, such as WBA (woody biomass ash), is particularly important. The presented research assessed the effect of soil application of WBA in conjunction with PFM (post-fermentation mass) on the stabilization of soil properties. WBA was applied in three increasing doses (0.5, 1.0, and 1.5 HAC). PFM was applied as follows: ULF (unseparated liquid fraction), SSF (separated solid fraction), and SLF (separated liquid fraction). PFM doses were balanced with the amount of nitrogen introduced into the soil. The study was based on a pot experiment with maize. The applied doses of WBA had a highly significant and positive effect on the stabilization of basic soil properties. After WBA application, hydrolytic acidity decreased (by 30%), soil pH increased (by 1.83 units), total base cation increased (by 66%), available potassium (by 119%), phosphorus (by 44%), and magnesium content (by 38%) as well as electrolytic conductivity increased (by 11%). Furthermore, an increase in soil carbon content and an improvement in the carbon-to-nitrogen ratio were noted. These observed results were further enhanced by the simultaneous application of WBA and the used PFM fractions, of which the liquid fractions (ULF and SLF) had the strongest effect.