The paper gives a brief overview and describes the main results of comparison research in grassland management of conventional and organic farms. The aim of this study was to assess yielding ability and biodiversity of leys depending on the nutritive status of soil. The investigation based on field experiments that were carried out in several regions of Estonia: Laeaene (West), Harju (North) and Voru (South-East) county in 2001. In the research on the productivity of grass-clover leys of the first harvest year was measured the DM yield and content, the botanical composition of the sward and the concentration of crude protein on grass. The soil pHKCL and content of organic matter were measured, also the content in soil of soluble plant nutrients P, K, Ca and Mg was estimated by AL- (ammonium acetate extraction) method. The soil profiles were described and soils were classified. The dominant soil types in farms of West-Estonia were Calcic Cambisols and in North-Estonian farms Calcic Gleysols, in South-East Haplic Podzols types prevailed.

One of the most serious diseases of the potato crop worldwide is late blight caused by Phytophthora infestans (Mont.) de Bary. Most growers control the disease by applying fungicides at regular intervals of 8-10 days from the time of row closing until the end of the growing season. The NEGFRY model is used for timing the chemical control of potato late blight. The NEGFRY model is based on two existing models, the "negative prognosis", for forecasting the risk of primary attacks, and a model for timing subsequent fungicide applications during the season. The main objective of NEGFRY is to get high yield and quality with minimum use of fungicides. Present work underlies the experiments that were arranged in 2000 and 2001 at the Jogeva Plant Breeding Institute. Two potato varieties with different resistance to late blight were taken to the experiment in both years: susceptible 'Adora' and modarately resistant 'Anti' in the year 2000 and susceptible 'Berber' and 'Anti' in 2001. NEGFRY gave highest economical effect among six tested treatment regimes.

In order to identify the quality of natural Silver birch stands in Latvia, fifteen sample plots covering all country's regions were established. Stem quality affecting morphological traits - stem straightness, branch angle, branching thickness and branching patterns were measured and assessed to all birches in sample plots. To compare the stand's quality, the integral quality indicator was introduced. According to results obtained in plots, most quality birch stands in Latvia are located in East and North parts of Latvia. The best stands proved to be in Aluksne and Smiltene. Birch stands in West part of Latvia had stems of substantially lower quality. The best quality stand in this region was birch stand located in Tukuma's head forestry.

Flooding of Nemunas floodplain preserves the natural retention capacity of pollutants in water of the main canal as well as improves farming conditions on the inundated meadows of the valley. It was established that nitrogen concentration was decreasing by 20-50 % causing self - purification process on the flooded meadows. Nitrogen retention is mostly observed in the zones of stagnant water. It depends on the velocities of flood current. Heavy metals and nutrients are absorbed by tiny clay and silt particles deposited in the meadows. By the means of mathematical modelling it was established that about 37% of suspended sediments deposited in the flood plain. During the study period (1950-1991), the soils in the valley were covered by 50-60 t ha*[-1) of deposits and were naturally fertilised with 250 t of potassium, 950 t of phosphorus, 38.000 t of calcium and 147.000 t of organic matter saturated with nitrogen. In order to increase those quantities it would be efficient to increase the water discharge and bush cover in the Delta.

The author of this publication offers to analyse and appraise development problems of a pupil's personality in pedagogical environment. This ensures respect for the holistic principle in scientific investigation. Pupil's qualities of personality, its structure and advance, dynamics of development, in the author's opinion, are necessary to be investigated not only in different separate spheres of their activity and manifestation, but in a unity determined by the holistic principle in pedagogy. The development of a personality takes place through interaction with the environment. The aim of the publication is to present a characteristic of interaction between a pupil's personality and rural school as a pedagogical environment in the context of topicality, contradictions, tendencies and problems in today's education.

This paper investigates the natural resources, business and social infrastructure and also the demographic structure of the local inhabitants of the municipalities, near the projected pulp mill. Possibilities and problems connected to the implementation of the pulp mill project are pointed out, also extra regional development is discussed.

Training of a vocational teacher at a professional education oriented university is in parallels to concentric integration of profession and pedagogic (psychology) resulting in formation of student's professional consciousness that ensures a new quality of professional orientation.

Estimating water quality of rivers, lakes and other water bodies, their contamination is being modelled according to the quantitative changes of pollution factors and their appearance conditions. Water contamination is being determined considering one or another value of contamination factors. The modelling of the impact of pollution factors on water quality becomes problematic when the values of the factors can be estimated only approximately or cannot be estimated at all. It is rather difficult to define qualitative estimation of water contamination factors in comparative terms (scanty impact, average impact, etc.) applying only quantitative mathematical methods. In this case the method of fuzzy logic may be of great help. Fuzzy logic enables us to formalise the comparisons of the ojects or phenomena under discussion as well as eliminates the contradictions between qualitative and quantitative methods. Those two methods supplement each other and can be easily applied together. The objective of the study was to estimate the possibilities of fuzzy logic application for the evaluation of stream water quality.

The work contains the description of the current technical conditions of the water resources of the Baltezers region and drinking water consumption in Riga during 2003-2010.