A total amount of 90 pig tonsil samples were investigated to detect presence of Y.enterocolitica 4/O:3. Samples were collected in two large-scale Latvian slaughterhouses from five pig herds during February and March, 2006. Samples were investigated with direct plating onto selective CIN agar plates according to ISO 10273 method, with subsequent cold enrichment for 2 weeks at 4 deg C in accordance with NMKL 117 method. Y.enterocolitica positive isolates were investigated for pyrazinamidase and lipase activity, indole production and salicine, xylose, trehalose fermentation. Slide agglutination reaction with commercial antisera O:3 was carried out for detection of Y.enterocolitica sevovars. Pathogen was isolated from all five herds with 30% mean prevalence. Incidence of Y.enterocolitica 4/O:3 depending on herd varied from 20 to 45%. High incidence of Y.enterocolitica in pig tonsils indicates that animals are important reservoir of this pathogen in Latvia. Further studies about incidence of Y.enterocolitica pathogenic bioserotypes in pig population and contamination pattern with pathogen in slaughterhouses are needed.

The mean content of minerals in grains varies significantly among different parts of the world as it depends on the type of grain growing conditions and fertilizer application. In this study, the content of minerals in the wheat, oat and barley grains of the crop of the year 2006 from different regions of Latvia were investigated. The grain samples were analysed for K, Mg, Ca, Na, Cu, Mn, Fe, and Zn using Atomic Absorbtion Spectrometer, and for P using spectrophotometer. Phosphorus content in different types of grains varied from 3.10 to 5.65 g kgE-1, potassium - from 4.37 to 6.10 g kgE-1, calcium - from 0.40 to 1.40 g kgE-1, magnesium - from 1.20 to 1.68 g kgE-1, manganese – from 14.50 to 55.54 g kgE-1, copper - from 3.35 to 6.01 g kgE-1, zinc - from 18.72 to 31.84 g kgE-1, iron - from 42.39 to 120.40 g kgE-1, and sodium - from 32.34 to 55.52 g kgE-1. The greatest difference was found between the content of manganese and iron in barley, wheat and oat grains, but small difference was between the mean content of P, K, Zn, Cu, Mg, and Na.

Area of grey alder stands is 190.6 thousand ha that is 6.8% of the total area of forests in Latvia with average volume 31.3 million m**3 4.9% of total yield is in the state forests, but 95.1% in the forests of other managers. Scientific literature affirms that grey alder is easy growing trees species. Its stands are quick - growing and wood has high heating capacity. Empirical data in 1 - 10 years old stands are collected from 25 m2 sample plots, 15 in each stand. Data from older (11 - 30 years) stands are obtained by 6 - trees - sample - plot method, from 180 trees in each stand. Number of trees (y) in the stands diminishes with age (x) that is characterized by regression equation y = 72534xE-1.1488. The division of the number of trees in diameter classes characterizes distribution of trees diameters in stands and trees differentiation processes within the stands. At the age of 1 - 5 years, grey alder stems were in diameter classes under 2 cm but at the age 6 - 10 years - 2 and 4 cm. In 11 - 15 years old stands 89% of all the measured trees are included in four (4 - 10 cm) diameter classes. It pointed to growing differentiation of diameters of the trees. Starting from age 16 - 20 years, 76 - 89% of the trees were of four to five diameter classes (10 - 18 cm). The average standing volume in 11 and 15 year old stands was 110 m3 haE-1 and it increased step by step to 180 m3 haE-1 in the stands of age 26 - 30 years. The basal area in the age of 15 - 30 years varied between 20 - 26 m2 haE-1. The average diameter reached 15 cm in stands of 25 -30 years.

The manufacturers of wood-based panels are interested to get easy and cheap method for determination of characteristic values of panels. The correlation between European standards EN 789 and EN 310 tests results can be used as an alternative procedure for determination of characteristic values of bending properties. The correlations between two results of bending properties determined by testing methods of European standards EN 789 and EN 310 are studied in this paper. The ratio of EN 789 test results divided with EN 310 test results (ratio of EN 789/EN 310), depending on panel thickness and glue type, was examined. Samples from 846 panels of birch (Betula sp.) plywood with thickness ranging from 6.5 to 30 mm and two glue types - phenol formaldehyde and melamine urea formaldehyde resin - were used for verification of the correlations. The results show that the panel thickness influences the ratio of EN 789/EN 310 and the highest ratio were found between 12 and 15 mm panels. When the panel thickness is increased or decreased, the ratio of EN 789/EN 310 decreases significantly. The regression equations for each thickness of plywood are presented. The difference between plywood glued with phenol formaldehyde and melamine urea formaldehyde resin glues was not found.

This article presents the description of oak woodland key habitats and their importance in the maintaining of biodiversity as well as a necessity of management and monitoring. The lichens Lichenes and its percental cover features have been described. The exposition of lichen species depending on the cardinal points has been analysed. The article presents the characteristics of ecological indicators of lichens in the objects. The lichenoindicative evaluation and comparison of oak woodland key habitats in Latvia have been carried out.

Basing on the economic, ecological and social points of view, the polder systems in the Nemunas lowland are considered as unique, requiring a great deal of annual state subsidies. According to the land-improvement programme, during the period of 2006-2008, Lithuanian polder system are planned to be yearly granted 2.15 million euro from the State budget, whereas the local administration of Silute district, which is exploiting the polders of the Lower Nemunas - more than half of the sum (63%). The article includes the analysis of exploitation expenses and statistical estimation of the Lower Nemunas' polders during the period of 1996-2006 as well as the investigation of the funds distribution on routine repairs, reconstruction and maintenance work. The average annual expenses on the pump stations, dikes, ditches and roads during the research period were determined. The analysis of the previous decade's expenses shows that the statistical average of the expenditure on the polder systems of Silute district amounts to 0.68+-0.13 million euro a year. The yearly renovation of polders depreciation should be obviously awarded a grant of the amount not less than 0.72 million euro.

The paper deals with the analysis of ground water quality when slurry is applied on crop rotation fields. The investigations were carried out in Juodkiskis study object of the Lithuanian Institute of Water Management in 1995-1998. According to the average concentrations, the quality of ground water samples taken from the borehole arranged in Juodkiskis test field was good compared with hygienic rates for drinking water. All samples taken for the estimation of ammonia and nitrate nitrogen amount were of good quality. However, nitrate-N concentration increased to 5.5-5.6 mg lE-1 in some periods. Having compared actual phosphate phosphorus concentrations with the allowable ones it may be confirmed that ground water is not polluted with phosphates as phosphate phosphorus concentrations did not reach P-load permissible for drinking water. Considering the correlation connection between ground water level and chemical compounds concentrations, it was determined that ammonia nitrogen and phosphorus compounds concentrations were influenced by ground water level fluctuations (correlation coefficient r = 0:54 and r = 0:62). (Given r values correspond to the reliability criterion tactual is greater than ttheor95%). Lower ground water levels in a borehole determine higher N - NH4**+, P - PO4**- and Ptotal concentrations. No relation between nitrate nitrogen (N - NO3**-), Ntotal and K**+ and ground water level fluctuations was determined.

At rural enterprises, besides the traditional resources - natural, financial, and human capital - there is some other kind of capital - it is social capital. Foreign scientists have done a lot of researches on it. The nature of social capital and its role in economics is not much studied in Latvia. The present scientific article reflects consumptions on social capital by different foreign scientists. The World Bank as an institution has also approached to the research of social capital. It studies social capital at institutions. The World Bank describes the social capital of two kinds. The scientific article characterizes Pieriga region. Rural enterprises and businessmen of agricultural, industrial and service branches in Pieriga region have been enquired. By the results of the enquiry, the presence of social capital in rural enterprises and its impact on their development have been analysed.

The process of creation of the informative systems based on the account of such animals as horses, sheep and goats is analyzed in the work. Three structural models are created and their comparative analysis is conducted. As a result of analysis the general elements of structures, characteristic to each model were found. The Meta modelling approach to facilitate the system was used. The system has a more abstract structure and allows dynamically to adding not only the animal specimens but also new types of attributes in fly during runtime. Recompilation of the system is not required there is no necessity of the analytical restructuring of the model, the absence of type explosions is guaranteed in a database because not a new table-type, but a new record in one or two tables is added.

Field trials were carried out on organic farming fields at the Research Institute of Agriculture of the Latvia University of Agriculture (LLU). The influence of harrowing (without harrowing, before emergence, at the stage of tillering, before emergence and at the stage of tillering) depending of pre-crop (red clover, winter rye for grain, bare fallow and green manure) and use of stable manure (60 t haE-1 or without) on the weediness and yield of spring barley 'Sencis' was tested during 2003-2004. In spring barley, 18 species of weeds were established at the stage of earing during 2003-2004. The most widespread of perennial weeds were Elytrigia repens (L.) Nevski and Sonchus arvense L. The dominant annual weeds were Chenopodium album L., Stellaria media L., Capsella bursa-pastoris L., Polygonum spp., and Matricaria inodorum L. The number of annual weeds at the stage of earing differed during the years 50-160 (in 2003) and 33-118 (in 2004) annual weeds per mE-2. The influence of harrowing on the number of annual weeds was different during the testing years. The influence of harrowing on the grain yield was negligible during 2003 and 2004.