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The aim of the study is to determine changes in the morphological, physical and chemical properties of soils of Lithuanian agroecosystems caused by their anthropogenic transformation. Summarized data on 33 soil profiles, 5 relatively natural mature forest soils and 28 anthropogenically affected soils, investigated in 2015-2018, are presented. The structure of the soil profile and its variation, the thickness of Ah(p) horizon, the soil bulk density and total porosity, the soil organic carbon content and its qualitative characteristics in A horizon were examined. The study showed that Retisol (RT) and Planosol (PL) are mostly degraded ex-situ due to the agrogenical effect: disruption of the genetic profile and the removal of the soil organic carbon (SOC) are ongoing, therefore bulk density increases and total porosity decreases. Luvisol (LV), Cambisol (CM) and Gleysol (GL) are most affected by in-situ erosion: soil is compacted and total porosity is decreasing. The loss of SOC due to the removal of biomass contributes to the increase in soil density. The Retisol profile horizons in the upper part are changed from O-Ah-E-E/B to Ap-E/B. The natural Luvisol profile, described as O-Ah-E-Btg-BCkg, is changed into the sequence of Ap-Ahm-BCk. In archaeological areas, the initial topsoil O-A horizon transformed to a complex cultural layer consisting of terric Ah and buried Ah horizons. When anthropogenic soil Ah soil horizons become deeper (from 10-15 up to 25-30 cm thick) due to deep ploughing, the E horizon is disturbed and partially mixed and incorporated into Ap horizon. The properties of Ap horizon differ from those of Ah and AhE horizons, from which it has developed. The bulk density increases from 0.8-1.08 to 1.55-1.75 Mg m-3 , while the SOC content decreases from 30-40 to 11-14 g kg-1 in Ap horizon. Humification degree in the soils of mature forest is amounts to about 25.5%, while in agrogenized soils it varies greatly and amounts about 14%. The most favourable conditions for soil organic matter (SOM) humification and SOC sequestration are in perennial grassland, when biomass is not removed, as well as in mature mixed forests. The ratio of carbon of mobile humic and fulvic acids (C MHA :C MFA) varies from 1.02 to 1.54 in relatively natural soils of mature forest, in arable soils varies within the range of 0.58-1.02, and in meadows-0.91-2.82, indicating declining SOC sequestration. In order to solve soil problems related to soil agrogenization, the aspects of SOC content and intensity of land use should be considered. Usage of Luvisol and Cambisol for agriculture, crop rotations must be observed and organic fertilizers must be used in combination with mineral fertilizers. From soil conservation viewpoint, arable farming in Retisol and Planosol should be replaced by grassland and livestock farming.

The aim of the study was to evaluate six perennial grass species: lucerne (Medicago sativa L.), reed canary grass (Phalaris arundinacea L.), tall fescue (Festuca arundinacea Schreb.), cocksfoot (Dactylis glomerata L.), switchgrass (Panicum virgatum L.) and ryegrass (Lolium perenne L.), with a balanced composition of organic compounds and minerals, for their suitability for direct combustion in relation to grass species, chemical composition and growth stage. At the regrowth and heading / inflorescence emergence stages, the chemical composition of the biomass of the tested grass species was similar. Before regrowth in spring, the plants contained higher concentrations of carbon, lignin and cellulose and the smallest amounts of ash and nitrogen. Of all the grass species tested, the biomass of lucerne, tall fescue and particularly ryegrass was the most suitable for direct combustion, as it had the highest concentration of carbon (57.55%) and the lowest concentration of nitrogen (0.61%) and ash (4.48%). The findings suggested that the heating value of the biomass was determined by plant growth stage and chemical composition. It was the highest at the heading stage and before regrowth in spring. It was found that the biomass of lucerne produced the highest energy yield of 303 GJ ha-1 (a sum of two harvests). The biomass of tall fescue produced 185.2 GJ ha-1 , and that of cocksfoot-137.3 GJ ha-1. The biomass of reed canary grass produced a lower energy yield of 93.3 GJ ha-1. The analysis of the relationship between the heating value and chemical composition of the biomass showed a strong correlation between the heating value and acid detergent lignin (ADL) 0.548** (p < 0.01). The heating value was also found to positively correlate (p < 0.05) with cellulose (0.376*) and carbon (0.258*).