AimsOpencast lignite mining causes significant disturbances to the natural environment. It isn't only the plant cover that is destroyed, also the soil cover is damaged. Soils are replaced by dumps with material composition that properties differ significantly from natural soils. Reclamation of these areas is necessary.MethodsThis study presents the effect of forty-three years of agricultural reclamation involving alternating winter wheat and winter rapeseed in three fertilization treatments: 0- (without fertilization), I-NPK and II-NPK on the chemical properties of Technosols.ResultsThe investigation demonstrated that the Ap-horizon emerged in the case of I-NPK and II-NPK treatments. There was an improvement in chemical properties for the Ap-horizon as compared to 1978: soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P) and potassium (K) increased. The CaCO3 decreased, and SOC/TN ratio declined, while pH and cation exchange capacity (CEC) remained unchanged. For the Technosols' surface horizon of the 0-NPK, there were also temporal increases in TN and SOC with a decrease in the SOC/TN ratio, whereas P, K, pH, CEC and CaCO3 values did not change significantly.ConclusionIn the 43-year-old post-mining Technosols, under the effect of fertilization and cultivated plants, the Ap horizon has formed, while in the non-fertilized soil the AC and CA horizons. Soil that were fertilized had significantly higher SOC, TN, P and K values in the surface horizon than minesoils without fertilization. In the subsurface horizons, the properties of minesoils were similar regardless of fertilization.

The objective of this study is to explore the novel use of natural polymers like Humic acid, Lignin, and Lignite based hydrogels for the formulation of pesticides and fertilizers that would reduce the residues in soil and run-off water that pose a threat to human health and the environment. We synthesized hydrogels by grafting Humic acid, lignin, and lignite onto acrylic acid with N ' N-methylene bisacrylamide (MBA) for the ex-situ encapsulation of thiamethoxam, a common pesticide. Various characterization techniques including Fourier-transform infrared spectroscopy, Carbon-13 Solid-state Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance, X-ray diffraction, Thermogravimetric Analysis, and Rheology were employed. The release kinetics of thiamethoxam in water from the developed formulations were analyzed using the Korsmeyer- Peppas model and the Weibull model. Humic acid and lignin-based hydrogels exhibited a long-sustained release for 49 hours, followed by lignite-based hydrogels (38 hours). According to ANOVA results, the change of biopolymer proved to be an effective factor in reducing the water evaporation rate, which decreased from 99 % to 72.85 % in the soil amended with synthesized hydrogels. In conclusion, the novel formulations of humic acid, lignin, and lignite exhibit potential as slow-release vehicles for pesticides and fertilizers. This study provides valuable insights for the research community, addressing the need to develop effective strategies for mitigating pesticide residues in soil and water bodies. Humic acid, lignin, and lignite grafted poly(sodium acrylate) hydrogels have been synthesized and characterized by 13C CPMAS NMR, FT-IR, XRD, SEM, TGA, and Rheology. The release kinetics of thiamethoxam is studied using the Korsmeyer-Peppas and Weibull models. This study will reduce the environmental influences of pesticide runoff into the water and bring humic acids, and lignite out of the traditional soil context by applying them in modern fields along with lignin. image