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Soil transformations in catchment of disappearing Sumówko Lake (Brodnickie Lake District, Poland) Lake disappearing is a natural process which contemporarily escalates in consequence of human activity. It is estimated that within the area of Northern Poland from the last glaciation period (ca. 17 000 years ago) a half of lakes totally have disappeared. Areas exposed after water basins desiccation have become native rocks for new soils. Reduced water level results in changes of morphology and properties of the soils situated in direct vicinity of former water basins. The aim of this study was to estimate impact of the catchment groundwater level fall on morphology and properties of direct lake catchment soils, exemplified by the lake Sumowko (Northern Poland) as well as description of new soils formed of lake sediments. The analysis covered 11 soil profiles emerging within former lake basin (newly formed soils) and soils from direct vicinity of former lake (modified through ground water level fall). Obtained results prove that newly formed soils (Limnic Histosol Drainic and Haplic Gleysol) in majority are utilized as grasslands. Soils of the former lake surroundings prove relic features of gleying while they are also subject to mucking process because of dehydration.

The still-advancing soil degradation and the related losses of soil organic carbon stocks due to the limited inflow of organic residues in agro-ecosystems encourage more and more soil protection. Establishing meadow ecosystems is one of the key methods of agricultural land use preventing losses of organic carbon in soils. Based on the research on the properties of humic acids, it is possible to determine the advancement of the processes of transformation and decomposition of soil organic matter. The obtained results may allow for the development of a soil protection strategy and more effective sequestration of organic carbon. Therefore, the aim of the research was to determine the properties of humic acids defining the quality of organic matter of meadow soils irrigated for 150 years with the slope-and-flooding system. The research was performed based on the soils (Albic Brunic Arenosol) sampled from Europe’s unique complex of permanent irrigated grasslands (the same irrigation management for 150 years), applying the slope-and-flooding system: the Czerskie Meadows. 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 (ultraviolet-visible) range, hydrophilic and hydrophobic properties and the infrared spectra. The research results showed that the HAs properties depend on the depth and the distance from the irrigation ditch. The HAs of soils sampled from the depth of 0–10 cm were identified with a lower “degree of maturity” as compared with the HAs of soils sampled from the depth of 20–30 cm, reflected by the values of atomic ratios (H/C, O/C, O/H), absorbance coefficients, and the FT-IR (Fourier transform infrared) spectra. The mean values of the H/C ratio in the HAs molecules of soils sampled from the depth of 20–30 cm were lower by 8.2% than those from the depth of 0–10 cm. The mean values of the absorbance coefficient A4/6 in the HAs molecules of soils sampled from the depth of 20–30 cm were lower by 9.6% than in the HAs molecules of soils sampled from the depth of 0–10 cm. The HAs molecules of the soils sampled 25 m from the irrigation ditch were identified with a higher degree of humification, as compared with the HAs of the soils sampled 5 m from the irrigation ditch. The results identified that humic acids produced in the many-year irrigated sandy soils were identified with a high degree of humification, which proves the relative stability of the soil’s organic matter. It confirms the importance of meadow soils for the carbon sequestration process. It should also be emphasized that the research area is interesting, although hardly described in terms of organic matter properties. Further and more detailed applicable research is planned, e.g., monitoring of total organic carbon content and comparing the properties of irrigated and non-irrigated meadow soils. Continuity of research is necessary to assess the direction of the soil organic matter transformation in such a unique ecosystem. The obtained results may allow for the development of, inter alia, models of agricultural practices that increase carbon sequestration in soils. In the long term, this will allow for greater environmental benefits and, thus, also increased financial benefits.

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Generative tillers are a source of assimilates necessary for the seed formation. However, their excessive elongation, especially under high doses of nitrogen, increases the susceptibility to lodging. The growth of generative shoots depends, among others on the root biomass affecting nutrient uptake, and on the ability to form rhizomes, as well as on the competitiveness of parallel developing vegetative tillers. Two-replicate field experiments were performed in Poland (53°09′ N, 17°35′ E), to determine the effect of plant growth regulators (PGRs) (single application of chloromequat chloride (CCC) at BBCH 30-31 or sequential treatment CCC at BBCH 30-31 + ethephon (ET) or CCC at BBCH 30-31 + trinexapac-ethyl (TE) at BBCH 37-39, and N fertilization (40 and 70 kg ha−1) on the length of generative tillers, the weight of generative and vegetative tillers, the canopy height, the weight of roots and rhizomes, and on N uptake in Festuca rubra L ssp. rubra (strong creeping red fescue) and F. r. L ssp. commutata (Chewings red fescue). Chewings red fescue turned to be more sensitive to the retardants. Generative tillers were shorter after single application of CCC as well as sequential treatment CCC + ET or TE. The tillers of strong creeping red fescue were shortened only after the application of CCC + TE. In every PGR treatments the canopy height at harvest was greater than in the control. Increasing the N rate from 40 to 70 kg ha−1 caused the reduction canopy height of strong creeping red fescue. Increased production of above-ground biomass, especially generative tillers, resulted in an increase in N accumulation in Chewings red fescue, as compared with strong creeping. Increasing the nitrogen rate from 40 to 70 kg ha−1, despite the reduction of root dry matter weight, stimulated generative tiller dry matter accumulation but it did not affect the biomass of vegetative tillers.

The experiment investigated the effect of preparations of <em>Betula pendula</em>, <em>Chamomilla recutita</em>, and <em>Urtica dioica</em> on the initial growth of <em>Hordeum vulgare</em> under laboratory conditions. The experiment involved a water solution of sap from the trunk of <em>B. pendula</em>, an infusion from <em>Ch. recutita</em>, extracts from leaves and rhizomes as well as macerated herbage of <em>U. dioica</em>, at the concentrations of 2.5%; 5%; 10% and 20%. During the first four days of the growth of the test plants, the plant preparations tested had a stimulatory effect on the length of leaves and roots in all the cases. The leaf increases were greater than those of the roots and became smaller with an increase in the concentration of the preparations. Continued watering of <em>H. vulgare</em> seedlings resulted in a further increase in leaf length after the application of <em>U. dioica</em> macerate and <em>Ch. recutita</em> infusion, with a simultaneous increase in root length with the macerate of <em>U. dioica</em> and <em>B. pendula</em> sap used at the concentrations of 2.5–10%. The other extracts made from <em>U. dioica</em> leaves and roots, irrespective of the concentration applied, strongly reduced the increase in leaves and roots from 11 to 27%. The weight of roots and leaves in <em>H. vulgare</em>, over the entire range of the concentrations applied and irrespective of the duration of the experiment, was stimulated only by <em>B. pendula</em> sap. The extracts from <em>Ch. recutita</em> and <em>U. dioica</em>, especially the leaf and root extracts, significantly reduced the root weight of the test plant.

The content of lead, zinc, copper, nickel and chromium in the aerial and underground parts of M. sinensis from eleven years old plantation and M. sacchariflorus and M. giganteus from nine years old plantations were analysed in order to recognize what organs of the plant play the most important function as a metal accumulator. It was found that in the aboveground parts, lead, zinc and copper were accumulated mostly in leaves and nickel and chromium in stems of the studied species. In underground plant parts, especially in roots, zinc, copper and nickel were most abundantly accumulated, while rhizomes accumulated higher amounts of lead and chromium. The content of lead, zinc and copper was definitely lower in those plant organs than their content in soil. The content of nickel and chromium, on the other hand, showed the opposite dependence. A similar capacity for uptaking trace elements from soil was observed for M. sacchariflorus and M. giganteus, while M. sinensis it was much lower, which is confirmed by the values of the bioaccumulation factors. The translocation factor for trace metals in the studied grass species indicated great translocation of lead and nickel from the roots to rhizomes, and that of zinc to aboveground parts.