The aim of the research was to compare the effect of two types of organic sorbents—humic acid (HA) and biochar (BC)—in sorption-desorption processes of different polar pesticides, which residues are commonly present in arable soils and are potentially harmful for the environment. It also aims to advance the understanding of behavior of both ionizable and nonionizable pesticides in the presence of BC and HA in soils.

Biochar application is reported as a method for improving physical and chemical soil properties, with a still questionable impact on the crop yields and quality. Plant productivity can be affected by biochar properties and soil conditions. High efficiency of biochar application was reported many times for plant cultivation in tropical and arid climates; however, the knowledge of how the biochar affects soils in temperate climate zones exhibiting different properties is still limited. Therefore, a three-year-long field experiment was conducted on a loamy Haplic Luvisol, a common arable soil in Central Europe, to extend the laboratory-scale experiments on biochar effectiveness. A low-temperature pinewood biochar was applied at the rate of 50 t h⁻¹, and maize was selected as a tested crop. Biochar application did not significantly impact the chemical soil properties and fertility of tested soil. However, biochar improved soil physical properties and water retention, reducing plant water stress during hot dry summers, and thus resulting in better maize growth and higher yields. Limited influence of the low-temperature biochar on soil properties suggests the crucial importance of biochar-production technology and biochar properties on the effectiveness and validity of its application in agriculture.

The elimination of flooding and lowering of the groundwater table after large-scale river regulation allow deep penetration of soils by plant roots, soil fauna, and microorganisms, thus creating favorable conditions for advanced pedogenesis. Although the changes of the morphology and properties of agriculturally used drained alluvial soils in Central Europe have been well characterized, studies in riparian forests remain insufficient. An analysis of 21 profiles of forest soils located on the Holocene river terrace (a floodplain before river regulation and embankment) in SW Poland confirmed a noticeable pedogenic transformation of soil morphology and properties resulting from river regulation. Gleyic properties were in most profiles replaced with stagnic properties, testifying to a transition from dominant groundwater supply to precipitation-water supply. The development of a diagnostic mollic and cambic horizons, correlated with the shift in soil classification from Fluvisols to Phaeozems, and in the majority, to Cambisols, demonstrated a substantial change in habitat conditions. The transformation of alluvial soils may result in an inevitable modification of forest management in the river valley, including quantitative alteration in species composition of primarily riparian forests.

The aim of the presented work was to compare the results of grain size distribution measurement by an innovative dynamometer method, developed by the authors, with results obtained by the pipette and hydrometer methods. Repeatability of results obtained in the dynamometer method was also determined. The content of three fractions with equivalent diameters <0.002 mm, 0.002–0.063 mm and 0.063–2.0 mm was measured. The results were compared using ordinary linear regression and additionally in the repeatability analysis by RMA (reduced major axis regression). It was found that the proposed dynamometer method is characterized by good result repeatability with no systematic errors when compared with the pipette method. The RMSE (root mean square error) value when referring to the pipette method calculated for the three fractions considered in total was 4.9096 and was lower than the analogous for the hydrometer method, which amounted to 5.4577. Values of determination coefficients in the comparison of dynamometer method and pipette method are within the range of 0.9681–0.9951 for the different fractions. It was found that slightly larger differences in relation to the pipette method occurred for the fractions <0.002 mm and 0.002–0.063 mm, and smaller for the fraction 0.063–2.0 mm. Similarly, greater differences between repetitions in the dynamometer method were observed for the fraction <0.002 mm, and smaller for the 0.063–2.0 mm fraction. Possible sources of errors in the dynamometer method were discussed, as were proposals for their reduction.

The dynamometer method of determining particle size distribution was developed several years ago. The principles of sample preparation for this method are based on those used in other sedimentation methods. With improvements in these procedures, an investigation of the effect on obtained particle size distribution results by removing organic matter using hydrogen peroxide was proposed. For this purpose, the particle size distributions were determined in 50 soil samples with varying organic matter content, before and after organic matter removal. A comparative analysis of the results, including calculation of the Euclidean distance, was performed on both groups. It was found that differences in the particle size distributions of the soils after the application of hydrogen peroxide were difficult to predict, and irregular in both magnitude and direction. However, in light soils, the process of organic matter removal caused an increase in the clay fraction at the expense of the silt fraction, which decreased. In soils with a higher initial clay fraction, there were decreases in the clay and sand fractions, while the silt fraction increased.