Tillage is an agrotechnical practice that strongly affects the soil environment. Its effect on soil properties depends on the system and, more specifically, on the degree of soil inversion and loosening. Strip-till is a non-inversive method that loosens only narrow soil strips. In strip-till one-pass (ST-OP) technology, tillage is combined with a simultaneous application of fertilizers and seed sowing. In a static multi-year field experiment, the soil properties after application of ST-OP for 8 years were compared to those of soil under conventional tillage with the use of a moldboard plough to a depth of 20 cm (CT), and equally deep loosened and mixed reduced tillage (RT). A field experiment of these three treatments was performed since 2012 in sandy loam soil, Luvisol. A total of 44 features were examined that described the physical, chemical, biological, and biochemical soil properties in the 0–20 cm layer, and penetration resistance (PR), bulk density (BD), and soil moisture (SM) in the 25–30 cm layer. The influence of the ST-OP technology on the yield of crops was also determined. Multivariate analysis shows that the ST-OP method, in terms of affecting the soil properties, differs considerably from RT and CT treatments. The soil after the ST-OP method contained two- to four-fold more earthworms (En), with a mass (Em) 2- to 5-fold higher, than those in the soil following RT and CT, respectively. In the ST-OP soil the content of available phosphorus (Pa) and available potassium (Ka); the total count of bacteria (Bt), cellulolytic microorganisms (Bc), and fungi (Ff); and the activity of phosphatases (AlP, AcP) were significantly higher. Compared with CT, the content of total organic carbon (Ct) and its content in the fractions of organic matter were also higher, with the exception of humins (C_H). The yields of winter rapeseed and winter wheat using the ST-OP technology were marginally higher compared with those using the CT and RT technology.

Purpose The aim of this paper has been to determine the seasonal changes in the content of dissolved organic matter (DOM) in the soils under agricultural use based on assaying changes in dissolved organic carbon (DOC) and dissolved nitrogen (DNt) as well as determining the factors which can define the DOM in soils. Materials and methods The research has involved the soils under agricultural use sampled in the Kujawsko-Pomorskie province (Poland). Phaeozems and Luvisols were sampled from the depth of 0–30, 30–60, and 60–100 cm, November 2011 through September 2013, in November, March, May, July, and September. The soil samples were assayed for the grain size composition, pH, dry weight content, content of total organic carbon, and total nitrogen. Dissolved organic matter was extracted with 0.004 mol dm³ CaCl₂; in the DOM extracts, the content of dissolved organic carbon (DOC) and dissolved nitrogen (DNt) were assayed. The research results were statistically verified. Results and discussion It has been demonstrated that in the first year of research, the content of dissolved organic carbon in the soils was changing throughout the year. The highest differences in the content of that carbon fraction occurred across the soil sampled in autumn and the soil sampled in spring. In the second year of research, an inverse dependence was noted. DOC was migrating to deeper layers of the soil profile; yet, the migration got more intensive in summer. The content of dissolved nitrogen was not changing significantly throughout the year. Higher DNt content in the surface layer, in general, resulted in a higher content of dissolved nitrogen in deeper profile layer, which could have been due to leaching of the nutrient deep down the soil profile. Conclusions The content of dissolved organic carbon was significantly related to the content of total organic carbon and total nitrogen. Significant changes in the content of dissolved forms of nitrogen were reported in the profile of Phaeozems due to mineral fertilization and irrigation. The soils where irrigation and higher nitrogen rates had been applied demonstrated a higher content and share of soluble forms of nitrogen, as compared with the soils non-irrigated and the soils where lower nitrogen rates had been supplied.

The aim of this paper has been to determine the importance of the strip-till method for the content of carbon and the quality of organic matter as compared with plough and ploughless tillage. The question to answer has been to what extent strip-till can contribute to carbon sequestration and thus be part of the strategy of counteracting climate change. The research involved soil where conventional tillage (CT), strip-till (ST), and reduced tillage (RT) were applied. These systems differ completely in the way they affect the post-harvest residue, i.e., “plant residue management”. For air-dry soil samples, the following analyses were made: the content of total organic carbon (TOC) and total nitrogen (Nt), content of dissolved organic carbon (DOC) and dissolved nitrogen (DNt), and the fractional composition of humus. In the surface layer the content of TOC ranged from 11.96 (CT) to 13.88 g kg⁻¹ (RT) and DOC ranged from 209.9 (CT) to 230.5 mg kg⁻¹ (ST). The share of the fraction of fluvic acids (0–15 cm layer) changed from 15.51% (RT) to 18.81% (ST), the share of the fraction of humic acids was 9.36% (ST) to 11.60%, and humins were 68.90% (CT) to 72.6% (RT). These results demonstrated that the tillage system determines the properties of the organic matter of soil. In the surface layer (0–15 cm) and in the 30–50 cm layer the properties of the soil organic matter under strip-till had a greater similarity to the soil under ploughless tillage than under conventional tillage. Ploughless tillage and strip-till considerably limited the leaching of carbon and nitrogen from the surface layer to the 30–50 cm layer. Strip-till, similarly to ploughless tillage, is the tillage method which can be crucial for the process of carbon sequestration.

The aim of the research has been to determine the role of phenolic compounds in the processes of transformations of organic matter in meadow soils, leading to the formation of humic substances. The research has been performed based on the plant material and soil sampled from Europe’s unique complex of permanent grasslands irrigated continuously for 150 years applying the slope-and-flooding system, the Czerskie Meadows. Phenolic compounds were isolated from the plant material samples (hay, sward and roots) and soils (horizon A, AE and Bsv) and from the fraction of humic and fulvic acids. It was found that the contents of phenolic compounds decrease in the following order: hay > sward > roots > A horizon soil > AE horizon soil > Bsv horizon soil > A horizon fulvic acids > AE horizon fulvic acids > Bsv horizon fulvic acids > A horizon fulvic acids > AE horizon fulvic acids > Bsv horizon fulvic acids. A significantly higher share of cinnamyl than vanillyl and syringyl compounds in the extracts of fulvic acids and slightly higher in the hydrolysates of humic acids confirms the effect of the chemical composition of the plant material undergoing decomposition on the properties of the emerging humic substances.

One of the main tasks in the search for environmentally friendly crop-growing methods is to increase soil fertility by improving its physical, chemical and biological parameters. The aim of this study was to determine the effect that the long-term annual application of different types of soil fertility agents (exogenous organic matter: 1. manure, 2. straw in combination with nitrogen fertilization and liming and 3. the addition of biostimulants) had on organic matter properties, including humic acid (HAs) properties. The research was carried out on the basis of soil samples from a ten-year pot experiment which was set up as single-factor pot experiment with four replications. PVC pots with perforated bottoms were filled with soil samples taken from the tilled layer of an arable field where winter wheat was grown in monoculture. The pots were exposed directly to the weather and were left without vegetation. The soil samples were assayed for the content of total organic carbon (TOC), total nitrogen and fractional composition of humus. HAs were extracted with the Schnitzer method and analyzed for the elemental composition, spectrometric parameters in the FT-IR and UV-VIS range and hydrophilic and hydrophobic properties. In addition, EPR spectra were produced. The results showed that the content of organic matter compared to soil without additives increased with the use of manure and the use of straw in the CaO variant and in the form of a mulch. The content of dissolved organic carbon (DOC) ranged from 124.6 to 286.1 mg kg⁻¹ and had strong positive correlation with TOC content. The values of the ratio of carbon content in humic acids to carbon content in fulvic acids (CHAs/CFAs) ranged from 0.71 to 0.99. The use of a biostimulator—with or without the addition of straw—increased carbon sequestration in humic acid molecules, as well as their oxidation level and their share of hydrophobic fractions with the longest retention time. Thus, the addition of UGmax intensifies humification processes, leading to the formation of stable humic acid molecules.

Many studies report organic carbon stabilization by clay minerals, but the effects of land use and soil type on the properties of humic acids (HAs) are missing. The aim of the paper is to determine the effects of land use and soil types on the characteristics of HAs, which have a considerable influence on organic matter quality. It was hypothesised that the effect of the land use on HAs properties depends on the particular size distribution. The research was performed in three ecosystems: agricultural, forest, and meadow, located in Slovakia. From each of them, the samples of 4 soil types were taken: Chernozem, Luvisol, Planosol, and Cambisol. The soil samples were assayed for the content of total organic carbon (TOC) and the particle size distribution. HAs were extracted with the Schnitzer method and analysed for the elemental composition, spectrometric parameters in the UV-VIS range, and hydrophilic and hydrophobic properties, and the infrared spectra were produced. The research results have shown that the properties of HAs can be modified by the land use and the scope and that the direction of changes depends on the soil type. The HAs of Chernozem and Luvisol in the agri-ecosystem were identified with a higher “degree of maturity”, as reflected by atomic ratios (H/C, O/C, O/H), absorbance coefficients, and the FT-IR spectra, as compared with the HAs of the meadow and forest ecosystem. However, as for the HAs of Cambisol, a higher “degree of maturity” was demonstrated for the meadow ecosystem, as compared with the HAs of the agri- and forest ecosystem. The present research has clearly identified that the content of clay is the factor determining the HAs properties. Soils with a higher content of the clay fraction contain HAs with a higher “degree of maturity”.