The objective of the present studies has been to estimate peculiarities of nitrogen removal in constructed wetlands of different construction. In limited companies (LTD) 'Pastoge' and 'Nikola', constructed wetlands of vertical flow (VFCW) are arranged, while limited company (LTD) 'Agaras' has two-stage constructed wetlands of horizontal flow (HFCW). In all the objects the supplied wastewater is after primary treatment. Having compared the efficiency of ammonium and nitrite nitrogen removal in two types of constructed wetlands (VFCW and HFCW) it was determined that larger amounts of total nitrogen are removed in HFCW (38.1%) rather than in VFCW (24.4%). However, in VFCW smaller amounts of ammonium and nitrite nitrogen are discharged with wastewater. No significant effect of the fluctuations of ambient temperature on the removal of ammonium and nitrite nitrogen was observed in HFCW (difference in average values of cold and warm periods was 3-8%). A rather reliable relation (R2 = 0:738) was determined between ammonium nitrogen concentrations in wastewater outflow and HFCW load according to total nitrogen, however, ammonium nitrogen amounts in treated wastewater (when filter load according to total nitrogen is 0.3 to 4.6 g mE-2 dE-1) exceeded the maximum allowable concentration (MAC) and were fluctuating from 6 to 32 mg lE-1.

The objective of the present studies has been to estimate wastewater treatment efficiency of surface-flow wetlands for finishing treatment of secondary effluent. The studies have been carried out within the reconstructed wastewater treatment facilities in Babenai (Kedainiai district, Lithuania), where, after the initial wastewater treatment in the septic tanks and biological ponds, a plant filter has been set for finishing the wastewater treatment. The removal efficiency of the main pollutants in the filter like BOD5, suspended solids, total N (nitrogen), and total P (phosphorus) has become the focus of the analysis as well. Wastewater treatment efficiency analysis was done on base measurements taken in all seasons of the year within the period 2003-2006. Surface-flow wetlands are characterised by good removal efficiency of the organic pollutants. At the average load of the examined plant filter - 0.9 mg O2 lE-1 BOD5 (biochemical oxygen demand), the removal efficiency reached up to 61.2%. Low winter temperatures reduce the rate of removal for BOD and the biological reactions responsible for nitrification and denitrification. During the warm period of the year, the treatment efficiency of BOD5 was 70.8%, and during the cold one - 52.4%. However, the total N constituted up to 16.7% and 9.7% respectively. Due to the anoxic and anaerobic conditions in the filter, wastewater after the treatment on average contains 66.0% of ammonium nitrogen of the total N concentration. After a year, with the growth of plants the phosphorus removal efficiency improved and at the average load of the examined plant filter according to P 0.063 g mE-2 dE-1, on average 0.018 g mE-2 dE-1 of the total P was removed, i.e., the removal efficiency constituted 28.6%.

The most urgent environmental problem in cultivated land areas of Lithuanian karst region is the protection of subsurface water from technogenic pollution. In terms of subsurface water pollution, the ambience of sinkholes is considered to be particularly dangerous. The work was carried out in 2004-2006 in the district of Birzai. Having analyzed the regime of sinkhole water formed in the vicinity of sinkholes as well as the regime of ground water of their vicinity it was determined that this regime is different in respect of the local hydrogeological conditions. A common regularity was observed: during the snow thaw period and rainy period sinkholes are fed with water from ambient soil and with shallow ground water, during the dry period water accumulated in peat of the failures of sinkholes flows into the ambience, and during the particularly dry periods subsurface water abates in sinkholes and they start draining the ground water very intensively. Analyzing the interrelations of water quality indices it was determined that in most cases the quality of ground water in sinkholes and in their vicinity is closely related. Sinkholes with water level higher than the ground water level and with higher chemical compounds concentrations make no adverse effect on ground water quality due to comparatively low runoff into the environment. However, such sinkholes are considered to be potential pollution sources of lower aquatic layers. Nitrate nitrogen is one of the most harmful pollutants getting into the sinkholes from agricultural fields and farming land plots where mineral fertilizers are applied. Ground water of higher level polluted with the nitrogen is obviously polluting the subsurface water of the sinkhole as well.

After the private ownership of land was restored and a part of land reclamation structures was given to land owners, the intensity of land use has changed. In the areas of Lithuania, which are less favoured for agriculture, the land is not intensely used. Further financing of land reclamation of such areas from the state budget grants is economically inefficient as the return of relatively high investments is very low. With the changing of land reclamation infrastructure it is necessary to prepare measures which would facilitate rational, regional agricultural specialization corresponding to natural conditions. The routine procedure of financing the land reclamation has to be changed as well. The paper analyses the changes in usage of drained land areas and financing of the land reclamation sector in Lithuania during the last decade (1997-2007). The purpose of this research is to establish the criteria of the economical efficiency of drainage systems and to propose methods how to change the financing of state-owned land reclamation infrastructure. On the grounds of the carried out situation analysis, a methodology of distributing state grants for land reclamation to municipality budgets are presented. To have an efficient use of the state budget funds, the operation and maintenance of shared land reclamation systems have to be carried out according to the maintenance plans approved by municipalities, which would provide for arrangements and compensations due to conflict of interests arising when land plots are used in different ways. Possible ecological measures that could be applied when carrying out repair and reconstruction of drainage systems are discussed.

If among engineering phenomena exist nonlinear interconnections, they are expressed with help of corresponding nonlinear functions. Teaching the regression analysis for the engineering science students one of the important topic is method of Least Square Method (LSM) and their application in the nonlinear regression analysis. Based on experience at Latvia University of Agriculture, the illustrated approach of teaching of nonlinear regression topics for undergraduate students in engineering applications is presented. Teaching statistics on regression analysis, students usually have problems with interpretation of the transformed regression model parameters significance. The tasks of teaching using LSM in the nonlinear regression analysis are discussed. On the figure 1 regression dependence are shown between such sizes as age of pine-tree and his height. The main species in Latvia is pine-tree (47% from total Latvia forest area); growth of trees motion is stipulated by tips of growth circumstances (Statistical Yearbook of Latvia, 2005).

Recently, the graduates should not only be technically competent, but also they should be skilled in communication and team work, have social and global awareness, be self directed and prepared for life-long learning. Knowing of languages contributes to student personal development. However, passivity of the students in the English classroom is among the factors limiting not only active engagement in academic tasks, acquisition of communicative skills but also soft skills needed for future profession. Therefore, at Lithuanian University of Agriculture, where student-active teaching and learning has been applied the study of the most acceptable class work forms for breaking passivity and improving students' motivation in the classroom for learning English as a foreign language was performed. The most persistent problem for the passive students who are afraid of speaking is the inability to find right words to express themselves (31%), and the fear of making mistakes, criticism, and sounding foolish (almost 55%). The application of the active class-work forms seems to behave well over fighting the passivity and enabling acquisition of the most important skills both for foreign language acquisition and becoming perspective future employees. Team work in created by a teacher relaxed atmosphere in the fitted classroom was found to be one the ways for breaking silence and passivity of the students in the English class room.

The migration of many rural youngsters to bigger cities and other countries in order to find a place for better life and job is not only economic but also educational and up-bringing problem nowadays. The development of the Latvian countryside is closely connected with the investment of educated young people in the long-term creative development of the native country. Latvia University of Agriculture students consider that one of the reasons of leaving their native land rather easily is because they were not purposefully brought up in the field of the patriotism and the feelings of belonging to their native country. Higher educational establishments apply different study models dependent mainly on the aims of educational institutions. The aim of this work is to develop a study model of 'Rural tourisms' taking into account that the study course 'Rural Tourism' has its up-bringing potential which can help to increase the development of students' patriotic attitude during the acquisition of Latvian cultural and historic inheritance. The priority of the study course 'Rural Tourism' in Latvian higher educational establishments is supposed to contribute to the development of students' entrepreneurial skills but this direction does not increase the development of students' patriotism. The above mentioned developed study model is based mainly on the dynamics of the relationship between the study program and the development of students' patriotism.

Cereals, the yield of which is strongly influenced by a well-selected variety, belong to the most important crops of organic farming, grown on arable land. At first a questionnaire study was executed among organic farmers in 2006 to gain information concerning the choice of variety, structure of growing, and yield of cereals in the Czech Republic. The actual cultivars of wheat are bred to be suitable for intensive farming. Therefore, not all the actual cultivars are suitable for organic farming. The methodology of tests of the suitability of cultivars for organic farming was elaborated and tested in 2006. Particular morphological, biological and agricultural features were evaluated. Selected Austrian cultivars, which were recommended for in organic farming system and breeded strains were tested. It is difficult to achieve sufficient protein content in grain in the organic farming system. The fact that the protein content in landraces of wheat is higher than the protein content in modern breeded varieties was confirmed. These varieties adapted to local conditions very well. Most of the evaluated varieties contain more crude protein in grain than modern varieties and may achieve a very good-quality production, but on a lower yield level the same as varieties of emmer.

The research was done in 2006 with the aim to observe the earliness and sugar content of melons (Cucumis melo L.) in Tukums region of Latvia. Five lines of Latgale's melons ('8', '14', 'S4(3)', '5(2)', and '4(3)') and five varieties ('Noirdes Carmes', 'Ogen', 'Vedrantais', 'Cantaloup de Bellegarde', and 'Jaune Canaris') from South Europe were grown in high plastic tunnels: five plants from each line and variety. The most appropriate melon line for growing in Latvia conditions was selected according to earliness and sugar content. The study showed that Latgale's melons (Latvian origin) are most suitable for growing in high plastic tunnels under Latvia's conditions. Also some of South Europe melon varieties proved to be suitable for growing in Latvia conditions. All Latgale's melon lines were earlier than South Europe varieties. The highest sugar content was observed in Latgale's melon line '8' (113 g kg¡1) and in South Europe varieties 'Jaune Canaris' (110 g kgE-1) and 'Cantaloup de Bellegarde' (96 g kgE-1). The research demonstrated that in Latvia successful cultivation of melons is possible by using high plastic tunnels.

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.