In recent years, sustainable agriculture has revitalized interest in crop rotations and their effects on crop performance and agroecosystem biodiversity, including weeds. This article used winter rye as an example and focused on the crop rotation (CR) impact on species, taxonomic and functional diversity of weed communities and analysed the contribution of crop rotation to protecting yield and regulating weed abundance. Long-term continuous rye cropping (CC) provided a background for comparison. Two variants of plant protection were also adopted: herbicide application (H+) and no plant protection (H−). The data from the 10th, 30th and 50th years of the experiment were included in the analysis. Diversified crop rotation with no chemical protection resulted in a satisfactory rye yield and reduced weed abundance—especially problem species—without a decrease in weed species diversity or functional diversity. When rye was grown under crop rotation, the herbicide application had no effect on yield protection, but it was harmful to weed biodiversity. The rye yield correlated negatively with weed biomass, but did not show a link with weed biodiversity. Continuation of long-term experiments as a research basis for contemporary and future scientific challenges is necessary.

The article analyses and evaluates the possibilities of using oak bark, oak leaves, and their mixtures for biofuel. The preparation of this waste for the burning process (milling, granulation) has been investigated and the results have been presented together with the analysis of the prepared granules’ properties—humidity, density, strength, elemental composition, ash content, caloric value, and others. The moisture content of the oak waste granules ranged from 8.1% to 12.5%, and the granules’ density ranged from 975.8 to 1122.2 kg m⁻³ DM (dry matter). The amount of oak ash found was very high (from 10.4% to 14.7%)—about 10 times higher than that of wood waste granules. The calorific value determined after burning the oak bark and leaves pellets was sufficiently high, ranging from 17.3 to 17.7 MJ kg⁻¹. This thermal value of oak waste granules was close to the calorific value of the herbaceous plant species and some types of wood waste. The environmental impact of burning the granules of oak waste was also assessed. The harmful emissions of carbon monoxide and dioxide, nitrogen oxides, and unburnt hydrocarbons into the environment were found to be below the permissible limits for the incineration of oak waste granules. The highest CO gas concentration, determined when burning the oak leaves, was 1187.70 mg m⁻³, and the lowest NO_x concentration, determined when burning the oak bark and leaf mixture granules, was 341.2 mg m⁻³. The coefficient of energy efficiency R of the granulated oak leaves biofuel, when the oak waste biomass moisture content was reduced by 10%, reached 3.64. It was very similar to the results of previous studies of various types of granulated straw biofuel (3.5–3.7). The research results presented show that, given that the main parameters of oak waste meet the basic requirements of solid biofuel, oak bark, leaves, and their mixture can be recommended to be used as solid biofuels.

Field studies with the large-stemmed plant Artemisia dubia (A. dubia) have been carried out at the Vėžaičiai Branch of LAMMC since 2018. According to three years of experimental results, annual dry matter (DM) yield varied from 7.94 to 10.14 t ha⁻¹. Growing conditions, nitrogen application level, and harvesting time had statistically significant impacts on A. dubia productivity. The most important tasks of this article were to investigate and determine the factors influencing A. dubia plant biomass productivity and the evaluation of technological, power, and environmental parameters of plant biomass utilization for energy conversion and the production of high-quality solid biofuel pellets. For the experiments, six variants of A. dubia samples were used, which were grown in 2021. Plants were cut three times and two fertilization options were used: (1) no fertilization and (2) fertilization with 180 kg ha⁻¹ of nitrogen fertilizer. These harvested plants were chopped, milled, and pressed into pellets. The physical–mechanical characteristics (moisture content, density, and strength) of the A. dubia pellets were investigated. During this study, it was found that the density in the dry mass (DM) of the pellets ranged from 1119.86 to 1192.44 kg m⁻³. The pellet moisture content ranged from 8.80 to 10.49%. After testing pellet strength, it was found that the pellets which were made from plant biomass PK-1-1 (first harvest without N fertilization) were the most resistant to compression, and they withstood 560.36 N of pressure. The dry fuel lower heating value (LHV) of the pellets was sufficiently high and was very close to that of the pine sawdust pellets; it varied from 17.46 ± 0.25 MJ kg⁻¹ to 18.14 ± 0.28 MJ kg⁻¹. The ash content of the burned pellets ranged from 3.62 ± 0.02% to 6.47 ± 0.09%. Emissions of harmful pollutants—CO₂, CO, NO_x, and unburnt hydrocarbons (C_xH_y)—did not exceed the maximum permissible levels. Summarizing the results for the investigated properties of the combustion and emissions of the A. dubia pellets, it can be concluded that this biofuel can be used for the production of pressed biofuel, and it is characterized by sufficiently high quality, efficient combustion, and permissible emissions to the environment.

Diversified crop rotation (DCR) has re-gained attention worldwide as a non-chemical practice for increasing the sustainability of cereal production systems. This study focused on comparing the effects of two weed management strategies, DCR (the six-field system: potato–oat–fiber flax–winter rye–faba bean–winter triticale) without the application of a herbicide (DCR strategy) and with the application of a herbicide (DCR + H strategy) on the yield of winter triticale and on the biomass and species, taxonomic, and functional diversities of weed communities. In addition, the responses of two triticale cultivars, Trapero and Borowik, to the weed management strategies were evaluated. Data from five growing seasons (2017–2021) of a long-term experiment (Bałcyny, northeastern Poland) are presented. The DCR strategy proved less effective in protecting the triticale yield than DCR + H but provided greater weed species, taxonomic and functional diversities. Borowik had a higher yield and responded to herbicide abandonment with a lower yield loss. When the DCR strategy was used, Borowik was more competitive against weeds than Trapero without reducing weed diversity. The triticale yield correlated negatively with weed biomass and diversity, and weed diversity and weed biomass were positively correlated. The findings show that winter triticale can be grown in DCR without the application of a herbicide if a high-yield, competitive cultivar such as Borowik is used. Growing such a cultivar under DCR conditions without the application of a herbicide promotes weed diversity; however, in years with less favorable weather conditions, it may be necessary to accept a moderately lower yield compared to the yield provided with herbicide protection. The relationship between weed diversity and weather conditions is a subject for further research.

The complex mutual interactions between soil properties and plants in high-biodiversity mono-cropping agro ecosystems have not been widely investigated. For this purpose, during 2009-2011, a stationary field experiment was conducted at the Experimental Station of the Aleksandras Stulginskis University to establish the effect of a multi-component agrocenose (maize, living mulch, weeds) on the physical properties of the soil. Spring oilseed rape, white mustard, spring barley, Italian ryegrass, black medic, Persian clover and red clover were sown as living mulch into maize inter-rows. The stability of >1.0 mm aggregates increased between the beginning and end of the maize vegetative period in almost all of the crops containing living mulch. The greatest competition for moisture content between the inter-crops and maize was observed at the beginning of the vegetative period because of living mulches of long growing seasons using the most moisture. In many cases, the shear strength of the soil was significantly reduced by the living mulch in the middle of summer, when it covered the maize inter-rows. These findings show that the monocropping of maize with living mulch stabilises or improves the physical characteristics of the soil, highlighting its potential for sustainable maize growing.