The aim of the study was to determine the agricultural usefulness of the ashes obtained following the combustion of wood of fourteen tree species (pear tree, apple tree, aspen, ash, alder, birch, poplar, hornbeam, pine, common walnut, oak, hazel, bird cherry and spruce) in home fireplaces. The following physical properties of the ashes were determined: colour, solubility, porosity, absorbability, compression strength, degree of fineness, moisture content and spreadability. In the ashes obtained from the combustion of wood in a fireplace furnace, the following parameters were determined: pH H2O , pH KCl (1 mole dm -3 KCl), pH CaCl2 (0.01 mole dm -3 CaCl 2 ) and total alkalinity in terms of the suitability of ashes as a liming agent. The contents of C tot. and N tot. were determined with a CHNS/O elemental analyser by Perkin-Elmer and the contents of other elements (macronutrients and heavy metals) were specified using the method of atomic emission spectrometry with inductively coupled plasma ICP-AES. Wood ashes are a source of macronutrients for plants. Their contents can be presented in the following series of decreasing values: Ca > C > K > Mg > P > S > N. Out of 1 t of wood ash, approx. 160 kg C, 6 kg N, 20 kg P, 98 kg K, 302 kg Ca, 39 kg Mg and 18 kg S can be introduced into the soil. The content of heavy metals in the analysed ashes was low, and exceeded the acceptable standards for their content in waste materials intended for liming soils. The analysed ashes exhibit good physical and chemical properties. They can be suitable for use in agriculture as a liming agent to be applied on medium and heavy soils.

The objective of the work was to evaluate selected properties of spent substrates used for growing button mushrooms (SMSs) and the content and quality of the organic matter in this material in the context of rational use for fertilisation purposes and potential impact on the soil environment. The materials were sampled at production facilities located in the east of Mazovia. The density and amount of spent substrate on shelves where mushrooms were cultivated were determined. The following were analysed in the laboratory: reaction, carbonate content, TC (total carbon) and TOC (total organic carbon) contents, total nitrogen, organic matter fraction composition, and humic acids properties. It was confirmed that this material had a marked potential to enrich soils in organic matter, nitrogen, and carbonates. The analysis revealed that the most important qualitative properties of the organic matter were related to the relatively high share of labile organic compounds (the fraction separated with 0.05 M H2SO4 and the fraction of fulvic acids). The humic acids had similar properties regardless of their origins. The humic acids (HAs) molecules displayed a substantial share of aliphatic structures which are typical of these materials at their initial decomposition stage. It can be assumed that, due to such properties, spent mushroom substrates are materials which can be directly introduced into the soil to improve their quality and prevent degradation.

A field experiment was carried out in 2016–2018 in a white lupin (Lupinus albus L.)-winter wheat (Triticum aestivum cv. ‘Bogatka’) crop rotation. The aim of this study was to determine the amount of nitrogen (N) that was biologically fixed by the white lupin crop in the first year of the rotation and to estimate how much of this N was then taken up from the lupin residues by winter wheat in the second and third years of the rotation. Biologically fixed N was determined by the isotope-dilution method (ID15N) by applying 30 kg N ha−1 of 15N-labeled fertilizer (15NH4)2SO4 (containing 20.1 at.% 15N) to the white lupin and the reference plant spring wheat. The yields of white lupin seeds and crop residues were 3.92 t ha−1 and 4.30 t ha−1, respectively. The total amount of N in the white lupin biomass was 243.2 kg ha−1, which included 209.3 kg ha−1 in the seeds and 33.9 kg ha−1 in the residues. The 15N-labeled residue of white lupin was cut and ploughed into soil. Our results indicate that 111.2 kg N ha−1 was fixed from the atmosphere by the lupin plants, with 93.7 kg ha−1 found in the seeds and 17.5 kg ha−1 in the residues. In the second and third years of the rotation when winter wheat was cultivated, the plots were divided into two groups of subplots (1) without N-fertilization (control) and (2) with an application of 100 kg N ha−1. In the first year of winter wheat cultivation, 20.0% and 21.0% of N from the crop residues was taken up by the control and N-fertilization plots, respectively, while in the second year, uptake was lower at 7.12% and 9.27% in the control and N-fertilized plots, respectively.

A b s t r a c t. The study addresses the problem of assessment of the chemical properties of compost produced on the basis of organic fraction of municipal waste, including the quantity and quality of organic matter. Six composts originating from central-eastern Poland were included in the research. The following analyses were performed: pH; salinity; content of C, N, P, K and heavy metals, fractional composition of organic matter (after decalcification, bitumens, fulvic acids, humic acids and post-extraction residue) and properties of humic acids (elemental composition and spectrophotometric properties). The analysed composts were characterised by a similar chemical nature. They were considered to be chemically and biologically silised. They were characterised by a significant potential for soil enrichment in soil humus and biogenic elements. The content of heavy metals in the tested composts did not constitute a barrier to their use as a fertiliser. The contribution of carbon of humic substances (separated by 0.1 M NaOH) ranged from 23.3 to 31.2%. Among humic substances the most humic acids prevailed, with the ratio of humic to fulvic carbon from 2.07 to 3.03. The elemental composition of humic acids of the tested composts was similar to those occurring in humus horizons of intensively used arable soils. Spectrophotometric parameters indicated a low degree of their humification.K e y w o r d s: compost, humic substances, humic acids

No abstract