Abstract. The feasibility of using lake sediments as fertilisers has been studied at the Voke Branch of the Lithuanian Institute of Agriculture since 1994. The experiments were carried out on a sandy loam cambisol on two backgrounds (without mineral fertilisers and with minimal rates of mineral fertilisers) in the crop rotation (maize, barley with under-crop, perennial grasses of the 1^st and 2^nd years of use, winter rye) with the application of calcareous (25 t ha^-1), organic (10, 40 t ha^-1) and siliceous (25, 100 t ha^-1) lake sediments and their mixtures with manure and limestone. Organic fertilisers were applied only to the first crop (maize) in the rotation.
Experimental evidence suggests that calcareous sediment and limestone declined soil acidity, whereas organic and siliceous sediments had no effect on soil acidity. Only the higher rate of organic (40 t ha^-1) and siliceous (100 t ha^-1) sediments increased the content of total nitrogen in soil by 0.002–0.021 and that of humus by 0.53 percentage units. Fertilisation with mineral fertilisers compensated for the amount of mobile phosphorus and potassium necessary for crop growth. 
The application of lake sediments had a positive impact on the quality of sandy loam cambisol physical properties. Organic and siliceous sediments increased the soil moisture content and porosity and declined the soil bulk density to a higher degree than calcareous sediment. Calcareous sediment improved the afore-mentioned soil physical characteristics to a greater extent compared with limestone. All rates of organic sediment gave a crop yield increase of 4–20%, 10 t ha^-1 of sediment with 25 t ha^-1 of manure gave a yield increase of 22–25%, and 50 and 100 t ha^-1 rates of siliceous sediment a yield increase of 8–30%.

Key words: sediments, manure, soil, properties, yield

Abstract. Three field experiments were carried out with the spring oilseed rape (Brassica napus L. ssp. oleifera annua Metzg.) cv. ‘Star’ to investigate the incidence, severity and harmfulness of Alternaria blight (Alternaria brassicae) and to test the possibility of reducing the disease pressure by fungicidal spray applications of 45% Sportak (a.i. prochloraz) 0.675 kg a.i. ha^-1 and 25% Folicur (a.i. tebuconazole) 0.25 kg a.i. ha^-1. The fungicides were applied at different times, i.e. after the first spots of Alternaria blight had appeared on the lower, middle and upper leaves or on siliques and at the end of spring oilseed rape flowering. Alternaria blight was present in crops of the spring oilseed rape cv. ‘Star’ in all the experimental years. The disease severity varied in individual years and was heavily dependent on the weather conditions (amount of precipitation and temperature). Of all the experimental years, the most conductive conditions to the spread and development of Alternaria blight on spring rape siliques occurred in 1998, when disease spots covered 18.65% of the surface area of siliques in the untreated plots. The tested fungicides had little effect on the disease incidence, however, prochloraz and tebuconazole applied on all dates declined the disease severity. The highest efficacy was recorded when the fungicides were applied after the first symptoms of Alternaria blight had been spotted on siliques. Tebuconazole suppressed the disease severity more effectively than prochloraz.
 In the year most favourable for Alternaria blight occurrence (1998), the seed yield in the untreated plots was by up to 0.07 t ha^-1 lower, and the disease severity on siliques was as much as 3.2 times higher than in the fungicide-sprayed treatment. The highest average spring rape seed yield increase resulting from fungicidal spray applications during the period 1997–1999 amounted to 0.040 t ha^-1. Fungicides declined the content of Alternaria blight diseased seeds per silique, increased 1,000-seed weight, however, no significant effect of fungicides was identified on the number of siliques per plant and the number of seeds per siliqua.
 

Key words: Alternaria brassicae, oilseed rape, disease incidence, disease severity, prochloraz, tebuconazole, seed yield 

 Abstract. The objective of the present research was to study the response of the peach cultivars ‘Spring Time’ and ‘Red Haven’ to nitrogen, phosphorus, potassium fertilisation and manure. The following fertiliser combinations were used: control (no fertilisation), N, P, K, NP, NK, PK, NPK, cattle manure, N+manure, P+manure, K+manure, NP+manure, NK+manure, PK+manure, NPK+manure. The research was conducted during a period of 10 years (from the 5^th to the 14^th year of the productive life of the peach trees). Application of N plus manure to peach trees of the cv. ‘Spring Time’ resulted in the highest fruit yield. Total soluble solids content (%) of fruits of the cv. ‘Spring Time’ did not significantly alter in comparison to the control for all the fertiliser combinations used. The lowest yield of trees of the cv. ‘Red Haven’ was recorded in the treatments P, PK, and the control. The highest percentage of split pits of fruits of the cv. ‘Red Haven’ was recorded in the control, while the lowest in the NK, and PK+manure treatment in comparison to all the others. The highest percentage of incomplete fertilised fruits was recorded in the PK and manure treatments in comparison to all the others. Trees of the cv. ‘Red Haven’ fertilised with P, K, and PK begun to produce diminished yields from the 11^th year. For both cvs., at the age of 15, trees fertilised with P, K, PK and the control had finished their economic cycle as yield decreased to very low levels. 

Key words: fruit firmness, peach fertilisation, peach fruit yield, total soluble solids content, split pits

 Abstract. The aim of the present work was to investigate the abundance and seasonal dynamics of wolf spiders in different plant communities. 
During the study, 529 individuals of wolf spiders were collected. A statistical analysis of the results indicated that, compared with clover, the number of wolf spiders was significantly lower on rape, wheat and fallow during the whole period of the experiment. It appeared that wolf spiders preferred habitats where plant cover was greater and older. In comparison with rape, the number of wolf spiders was significantly greater in the fallow variant. Both on rape and wheat the number of spiders was lower throughout the experiment, and a comparison of these variants showed no statistical significance. A comparison of wheat with fallow revealed no reliable differences in the number of spiders, although there existed a slight tendency in favour of fallow. On rape and wheat the number of spiders was lower during the whole experimental period, and a comparison of these variants with clover and fallow showed no statistical significance. 
The seasonal occurrence of spiders in the rape and wheat variants was different in comparison with the clover and fallow plots. In spring the activity of wolf spiders was low in the rape and wheat variants. The activity of wolf spiders significantly depended on the pest spraying times in the experimental fields. After treatments with Fastac (in May and June) in the rape variant and with a herbicide (in June) in the wheat variant, the number of spiders started to increase, however, this was only a small population peak and decreased very quickly. In the rape and wheat variants, the seasonal dynamics of the spiders showed one population peak in July, regardless of the treatments applied in May and June. A large number of juveniles was caught in pitfall traps of all test variants during the midsummer time. In May the number of spiders was low in the clover and fallow variants but started to increase quickly at the beginning of June. The seasonal occurrence of spiders shows a smaller population peak in June (on clover and fallow) and a large peak in July (only on clover). The peak was lower but broader in the clover variant. After the population peak, the number of spiders decreased again, because hay was made in the clover and fallow variants at the beginning of July. Spiders left those variants in one week (clover variant), or by the end of the vegetation period (fallow variant).
 

Key words: Araneae, Lycosidae, wolf spider, pesticide, plant community 

 Abstract. In this study, the Collembola population and their seasonal fluctuations were measured on light-textured field soils (Cambic Arenosol and Stagnic Luvisol) in Southern Estonia. A ten-year-old field experiment with potato and spring cereals in crop rotation under different fertilisation was the main sampling area. Additional research was carried out on sandy soils cropped with spring barley. There was also considerable but not drastic variation in chemical topsoil parameters between treatments and sites. Modified Mcfayden equipments were used to extract Collembola from soil samples. The average quantities of Collembola varied within the range of 700–14 300 and 0–600 individuals m^-2 for the eudaphic and hemiedaphic group, respectively. Application of organic manure and mineral nitrogen induced an increase in Collembola populations but the differences between treatments remained insignificant. The abundance of euedaphic Collembola under spring barley in September was several times higher than under potato. The influence of crop and probable amount of roots on the abundance of Collembola was more pronounced than that of fertilisation or soil texture and chemical features. It was hypothesised that the euedaphic Collembola community is subjected to density dependent regulation, despite significant year-to-year changes towards the end of the growing season. 

Key words: Collembola, cropping, fertilisation, seasonal change, soil texture

 Abstract. Larger areas of coastal grasslands can be found in western Estonia and in the islands of the west coast. Salt marshes of the Baltic Sea are not natural biotopes but developed by agricultural use, mainly grazing by beef cattle and horses. The main goal of the work is to discuss the properties of the investigated soils (Hyposalic Fluvisols), nutrient cycle in the plant-soil system and the influence of grazing on the coastal biotope. In this study, the coastal grassland soils in Hiiumaa have been investigated by using morphologic (depth of humus layer, bulk density) and chemical parameters (pH, total N and C, mineral elements P, K, Na, Ca, and Mg). The investigated soils contain high amounts of soluble salts K, Na, Ca, and Mg. The total nitrogen and humus content were high, but the content of P was low. 

Key words: coastal grassland soil, chemical parameters, humus layer depth, bulk density, impact of grazing

 Abstract. In order to determine the most appropriate cut height of wheat harvest, it is necessary to take into consideration not only the agronomical aspects, but some technical factors as well. In this research, the influence of cut height of harvest on the accounted losses and the fuel consumption of a combine harvester has been considered. It has been shown that the increasing of cut height up to straw-level in the threshed wheat mass 0.24 does not lead the accounted losses of the combine “CLAAS DOMINATOR – 106” over the permissible limits, without a necessity to install additional equipment on the machine. With such a technical solution, a decrease of fuel consumption of up to 30% can be achieved.

Key words: cut height, harvest losses, cereal, fuel consumption

 Abstract. The long-term use of heavy-weight agricultural machinery has caused extensive and lasting phenomena of degradation, especially in the basic layer of soil. The influence of soil compaction by heavy tractor on spring wheat and barley has been investigated. The field trials were completed on a Stagnic Luvisol (WRB), quite characteristic of Estonia but sensitive to compaction. The results of soil measurements demonstrated a strongly negative effect of wet soil compaction on soil physical characteristics and were in good connection with the number of compactions carried out. In order to find out the nutrient assimilation ability of plants on these soils, the amount of elements (N; P; K; Ca; Mg) in the dry matter of spring wheat and spring barley was determined. It appeared that the nitrogen uptake ability of spring wheat plants decreased almost by 30% and that of barley by 40% in the case of heavy soil compaction (4 and 6 times). As a result of compaction, the content of potassium and calcium in barley and spring wheat was decreased as compared with the non-compacted area. 

Key words: soil compaction, soil properties, spring barley, spring wheat, nutrients

 Abstract. The aim of the research work was to study microfungi in grain (spring and winter wheat) and grain feeds of domestic origin and determine their composition with special attention on toxigenic and allergenic species. 
The total number of fungi was estimated on wort agar or on the nutrient substratum of Czapek. The species and number of Fusarium were defined on the selective medium of Nash & Snyder. For a mycological survey of grain samples, the moist chamber method was used in the year of 1992. The fungi were determined by microscopy, using corresponding nominators (Raper et al., 1949; Raper et al., 1965; Arx, 1970; Bilai et al., 1988). The classification of Fusarium has been made according to Gerlach & Nirenberg (1982). The toxicity of isolated fungi was defined by means of a test organism, Bacillus stearothermophilus (Watson & Lindsay, 1982). Spring wheat of the years 1992, 1993, 1994 and winter wheat of the years 1992, 2002 and 2003, and spoilt grain feeds of the years 1997–2002 were investigated. 
About half of the identified 63 fungi species are either potentially toxigenic or allergenic. In 1992–1994; on average Alternaria spp. occurred on 72% of spring wheat seeds and on 45% of winter wheat seeds, Cladosporium spp. on 20% and 8% of the seeds, Aspergillus spp. on 6% and 9% of the seeds, Verticillium spp. on 13% and 23% of the seeds, Fusarium spp. on 23% and 64% of the seeds, respectively. Penicillium spp. was represented very differently: in 1992 and 1994 on 10%, in 1993 on 80–90% of the seeds. The species known as toxicants were also from the genera Chaetomium, Cochliobolus, Gliocladium, Mortierella, Mucor, Rhizopus, Stachybotrys, and Trichothecium. In spoilt grain feeds the potential toxicants were represented from the genera Acremonium, Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Rhizopus, and Trichothecium. Allergenic species were represented by the genera Epicoccum, Penicillium, Aspergillus, and Ulocladium. The toxicity of fungi isolated from grain, on the basis of the growth inhibition zone of B. stearothermophilus, was 0–7 mm, whereas on fungi isolated from spoilt feeds it was 0–18 mm. The most toxic fungi were Penicillium cyclopium, Penicillium sp., Trichothecium roseum, Aspergillus terreus, Paecilomyces varioti, Rhizopus nigricans, and Acremonium sp.
 

Key words: grain, grain feeds, mycoflora, toxins, toxigenic, allergenic, Bacillus stearothermophilus 

 Abstract. The effect of growth regulators – derivatives of the diethylamine chloride 3-DEC and morpholinium chloride 17-DMC – on the growth and productivity of the winter oilseed rape ‘Kasimir F1’ was studied.
 3-DEC and 17-DMC have been found to exert positive effect on the growth and development of the oilseed rape ‘Kasimir F1’ in autumn: it induced the growth of root collum, accumulation of monosaccharides in its tissues, leaf and root system formation, enhanced the endurance of this culture to wintering. Under the effect of these compounds applied in spring, stem growth was retarded and stem diameter as well as stem primary cortex ring and stele width increased, resulting in enhanced endurance to lodging. Thus, the compounds 3-DEC and 17-DMC, by modifying oilseed rape growth in autumn and influencing oilseed rape growth in spring, influenced the development of productivity elements. The extra seed yield under the effect of 3-DEC (250 g ha^-1) and 17-DMC (500 g ha^-1) in autumn was 350 and 455 kg ha^-1, and in spring 496 and 406 kg ha^-1, the control yield being 2,300 kg ha^-1. 
 

Key words: Brassica napus – morpholinium derivative – 17-DMC, dietylamine derivative 3-DEC, growth, productivity

 Abstract. Soil weed “seed bank” was studied according to harvesting time at different stages of spring barley maturity at the Research Station of the Lithuanian University of Agriculture, during the period of 1997–1999. The aim of the experiment was to identify weed seed species in the soil “seed bank” and changes in the total amount of the soil “seed bank”, harvesting spring barley at different stages of maturity. In two years of the three, earlier harvesting of spring barley at the milky stage of maturity essentially decreased reserves of the soil “seed bank”. The soil “seed bank” was established by counting 179–344 million ha^–1 seeds at the stem elongation–milky stage of spring barley maturity and 230–304 million ha^–1 seeds after harvesting spring barley at the hard stage of maturity. During the experiment, 20 weed seeds species belonging to 11 plant families: Amaranthaceae, Asteraceae, Boraginaceae, Chenopodiaceae, Convolvulaceae, Cruciferae, Euphorbiaceae, Lamiaceae, Polygonaceae, Scrophulariaceae, Violaceae, were identified in the soil “seed bank”. During the three years of the experiment, seeds of the white goosefoot Chenopodium album L. and the common chickweed Stellaria media (L.) Vill. dominated. 

Key words: weed species, soil weed “seed bank”, stages of spring barley maturity