Abstract. Research on novel energy crops -common mugwort (Artemisia vulgaris L.), cup plant (Silphium perfoliatum L.) and Virginia mallow (Sida hermaphrodita Rusby) was set up on a naturally acid Albeluvisol in West Lithuania. The study was aimed to evaluate the effect of year (growing conditions), liming and nitrogen fertilization on biomass yield, its structure as well as lime and nitrogen use efficiency. In many cases, year (or growing conditions) and N fertilization were two determinant factors for all studied parameters (number of stems per plant, stem height, fresh (FM) and dry mass (DM) yield). Liming material had the biggest impact on the number of stems, stem height and biomass yield of Virginia mallow and less obvious for other two species. Among three crops, the highest productivity was recorded for cup plant in the 3 rd harvest year -the average FM yield was 45.20 t ha -1 and that of DM -13.45 t ha -1 . The highest lime use efficiency (LUE) values for all three crops obtained in the 2 nd year of growing. The highest nitrogen use efficiency (NUE) was obtained in the 1 st (for common mugwort -30.71) and 2 nd year of growing (for cup plant and Virginia mallow -59.69 and 46.17, respectively).

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A field experiment was carried out at Vėžaičiai Branch of Lithuanian Research Centre for Agriculture and Forestry during the period 2008-2011. The study was aimed to determine the effects of various soil tillage methods: deep ploughing (20-25 cm), shallow ploughing (10-12 cm), shallow ploughless tillage (8-10 cm) and soil fertility improvement measures (plant residues, plant residues + straw, green manure 1 st cut + straw, green manure 2 nd cut + straw, farmyard manure 40 t ha -1 + straw) on the soil weed seed bank and weed incidence in a cereal-grass crop rotation. The soil of the experimental site is Dystric-Epihypogleyic Albeluvisol (ABg-p-w-dy) with a texture of sandy loam. In all experimental years, primary soil tillage had a significant influence on weed incidence in the crops of the rotation and on soil weed seed bank. The greatest amount of weeds, both in numbers and dry mass, in the crops of winter triticale and spring rape was determined in the shallow ploughless tillage treatment, in the crops of spring barley in the shallow ploughing treatment, and in the sward of red clover in deep and shallow ploughing treatments. All soil fertility improvement measures and their interaction with soil tillage methods did not have any substantial influence on the weed incidence in the rotation crops. The soil weed seed bank was 1.5 and 2.2 times greater in the shallow ploughing and shallow ploughless tillage treatments, compared with the conventional tillage treatment (deep ploughing). The influence of soil tillage methods manifested itself not only directly, but also through its interaction with soil fertility improvement measures. Regardless of the chosen soil fertility improvement measure, in all the treatments of shallow ploughless tillage, the soil weed seed bank was significantly greater, compared with the conventional soil tillage treatments. In the shallow ploughing and shallow ploughless tillage treatments there were found 25.5% and 41.5% more weed seed species in the soil, compared with the conventional tillage treatment. The seeds of Chenopodium album L., Persicaria lapathifolia L., Fallopia convolvulus L. and Viola arvensis Murray were found in all tillage treatments. The distribution of F. convolvulus L., P. lapathifolia L. seeds was significantly influenced by soil tillage only, that of V. arvensis Murray by soil tillage and its interaction with soil fertility improvement measures, and that of Ch. album L. by soil fertility improvement measures only.

With the increasing importance of energy crops, research on potential energy crops is carried out to identify plant species with high productivity and energy value. The field experiment with the new promising energy crop, Artemisia dubia (wormwood), was executed at the Vėžaičiai Branch of the LAMMC. The soil site was naturally acidic Retisol (pH 4.2–4.4). The species was investigated as an energy crop through the evaluation of its biomass productivity and some energetical qualities. According to the three investigation years, DM yield significantly varied depending on the growing season, cutting time and nitrogen rate. The highest average DM yield was observed in 2020—10.58 t ha−1. On average, the DM yield varied from 6.49 t ha−1 (first cutting) to 11.82 t ha−1 (third cutting). The DM yield was positively correlated with stem height and the mass of one stem. Nitrogen use efficiency (NUE) depended on the growing season, cutting time and nitrogen rate. Both N90 and N180 rates should be used for A. dubia fertilization. Energy growing analysis (including direct and indirect expenses) revealed that the highest share of energy expenses are due to indirect energy expenses (particularly nitrogen application). EUE (energy utilization efficiency) tends to decrease as a result of increasing nitrogen fertilization. Overall, A. dubia granules are characterized by a high calorific value.

Experiments were carried out in the Vėžaičiai Branch of the Lithuanian Institute of Agriculture (West Lithuania region) in [2002][2003][2004][2005]. The aim of this research was to estimate the ecological significance of perennial legumes used as green manure for the biological properties of triticale and rye and for diseases resistance. Residues of the perennial grasses tested and ploughed-in aftermath contributed different contents of nitrogen to the soil. The highest content of nitrogen was contributed to the soil with red clover residues and aftermath. Residues of white clover and aftermath ploughed in as green manure determined more favourable soil properties. This had a positive effect on the formation of biological parameters of cereals grown after white clover, which made it possible without mineral and organic fertilisers to produce on average 3.88 t ha -1 of triticale grain and 3.82 t ha -1 of rye grain, or by 1.09 and 0.28 t ha -1 more compared with their growing after red clover managed in the same way as white clover. Different growing conditions of winter cereals, i.e. different preceding crops, had a significant effect on the occurrence of scald and septoriosis.