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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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The current study hypothesizes that false flax (Camelina sativa L.), as a high-value biofuel feedstock, could be grown under humid conditions of western Lithuania and that nitrogen fertilisation could influence its seed yield and oil content. The following objectives were pursued: 1) to determine the optimum nitrogen fertiliser rate for winter (N 0 , N 50 , N 100 , N 150 ) and summer (N 0 , N 30 , N 60 , N 90 , N 120 ) types of false flax, 2) to estimate false flax seed oil content, its composition and feasibility to use it for the production of biodiesel fuel. The experiments were conducted in 2008-2011 at the Vėžaičiai Branch of the Lithuanian Research Centre for Agriculture and Forestry. It was revealed that the highest (1.28 t ha -1 , in 2010) and (1.29 t ha -1 , in 2011) as well as cost-efficient summer false flax seed yield was produced having fertilised with 90 kg ha -1 of nitrogen. Significantly highest (1.2 t ha -1 , in 2011 and 1.6 t ha -1 , in 2010) winter false flax seed yield was obtained having fertilised with N 100 . In our study, the seed oil content of summer false flax amounted to 40.3% and that of winter false flax was lower -37.0%. Nitrogen fertilisation (N 150 and N 120 ) increased protein content in winter false flax seed from 22.98% to 26.97% and in summer false flax seed from 20.53% to 23.23% and did not reduce seed oil content. Methyl esters of false flax oil have a high iodine value and an especially high content of polyunsaturated linolenic acid: it reached 38.2% in winter false flax oil and 34.3% in summer false flax oil. Therefore false flax methyl esters can be used as fuel for diesel engines only in mixtures containing 40-50% of methyl esters of animal origin (used frying oil or pork lard). The most effective antioxidant Ionol BF200 (optimal dosage -500 ppm) as well as the most effective depressants Wintron XC-30 (optimal dosage -1500 ppm) and Infineum R-442 (optimal dosage -1200 ppm) were selected for improvement of oxidation stability and cold flow properties of esters.

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.