The change from large scale agriculture to private small scale farming has resulted in a severe lack of plant protection means. Fields of Latvia have become more weedy for last four years. This fact shows the necessity for a change in the strategy of weed control. The effect of inexpensive and wide-spread herbicides 2.4-D and MCPA is insignificant in weed control. From 1994 Latvian State Centre of Plant Protection has been studying the occurance of weed species in the Central part of Latvia (Vidzeme), to make use schedules of necessary herbicides. The research was carried out jointly with the Latvia University of Agriculture. During the research carried out from 1997 to 2000, 60 weed species were established, but in all the crop sowings 10 species were predominant. The number of Elymus repens, Myosotis arvensis and Viola arvensis has increased during last four years. In Vidzeme region, from 1997 to 2000, it was stated that soil infestation of weed seeds varies from 4.5 to 11.1 thousand seeds per square metre on the average. Perennial dicot-weeds have shown the lowest variation coefficient, compaered with other weed groups.

It is well known that secretion of gastric acid is regulated neurally by the stimulation of n.vagus and humorally by the activation of histamine H2 receptors in parietal cells. The purpose of the investigation was to clear up neural and humoral regulation mechanisms of gastric acid secretion in the postnatal ontogenesis of calves. Four calves from 5 to 14 weeks of age with chronical fistulae in abomasum have been investigated. Two electrode pH-probe has been used for measures. Atropine sulphate (0,06 mg kg*[-1) IV infusion) has been used to stop function of n.vagus, and cimetidine (0.16 mg kg*[-1) IV infusion) to block humoral regulation. The results clearly show that both, atropine sulphate and cimetidine, demonstrate some blocking influence on the HCL of abomasum in calves of different age.

It is very important to use the exact investment model for energy enterprises. Giant investment is necessary for establishing continued energy systems using renewable energy resources. Demand of the heat energy usually is higher in a winter period compare to the summer time. Program combinations of different heating modus are researched using EnergyPRO.

The article describes present situation in further education of agricultural advisers and agronomists. There are three major challenges in rural and agricultural development today - coverage, sustainability and relevance. Changes in further education and information technologies play the most important role for agricultural advisers. Farmers want to study and get a certificate of agricultural education in order to be able to participate in different projects and acquire the EU structural funds. The article deals with the problem of using the EU structural funds for rural development. Agiculturists need professional advice from agricultural advisers.

Vocational education in all countries provides a specific learning system to their students and students are more motivated to take practical training for their further development. Agriculture-based vocational educational institutions have been facing problems of losing its students since 1998. To promote survival of these schools, a non-agriculture based curriculum was provided. Nowadays, in order to support agriculture-based vocational education, there is a need to do research on the prospects and needs of this type of schooling in Latvia. There is a need for new methods and models of curricula, based on practical needs of students, in order to promote management and marketing skills for future farmers.

However, the last case of tuberculosis to cattle was registered in Estonia in 1986, rapid and accurate diagnosting of the disease is still an actual veterinary problem. On farms, tuberculin testing has been regularly carried out showing that tuberculin positive cattle constitute 5,47% from all the herd. During 1997-2001, 23 clinical samples were isolated from the tuberculin positive cattle. Each sample was analysed with conventional morphological and bacteriological methods and by PCR. None of eleven mycobacterial cultures, isolated from the lymph modes of cattle, belonged to M. tuberculosis complex. There were seven cultures identified as M. avium and one as M. avium complex (MAC). The research confirmed that M. avium is the most frequently isolated bacteria causing NTM-Mycobacterioses in cattle in Estonia (63,6%). Two cultures of MAC were isolated from the milk of tuberculin-positive cows, verifying that milk can be a potential source of MAC transmission to man.

A questionnaire related to the wood drying was carried out among wood processing enterprises in Latvia to clarify the main problems and possible differences depending on production capacity and products. Deformation (twist, bow, spring, cupping etc.) during the kiln drying has been identified as the most important problem for all enterprises. Many problems are related to the product area as very often improper drying technology or incorrect drying schedule is used. Others are connected to the organization and control of drying process - optimisation of the drying schedule, energy consumption, kiln control unit, maintenance of measuring equipment, MC measurement, quality control during drying. There is a difference between softwood and hardwood drying in the product and sales area. Considerably more problems are recognized in hardwood drying (hardwood is often used in furniture production and has higher quality demands).

A field trial concerning optimisation of a mineral fertiliser (NPK) in the production of perennial ryegrass 'Spidola' seeds was established at the Skriveri Research Centre of the Latvia University of Agriculture in 1999. Experiments were conducted on sod-podzolic sandy loam soil (Luvic Phaeozem, WRB 1994). In 2000, the first seed production year, which was quite unsuitable in terms of climatic conditions, the nitrogen fertiliser showed significant influence on seed and straw yields. The use of phosphorous and potassium fertilisers in all combinations with nitrogen decreased the resistance of the crop to lodging.

To investigate flood and hydraulic parameters of the river, the hydraulic models of the river Daugava near Jekabpils have been built at the Rural Engineering Faculty of the Latvia University of Agriculture and at the Research Scientific Institute of Water Managmenet and Land. Several possible solutions have bee proposed as a results of these investigations, though only the most effective and economically acceptable variant should be selected.

Production of cereals is mostly processed by operating the machinery. Operation of machinery influences the yield, i.e. also the income on one side, but it is also one of the biggest sources of expenses from the other side. Increasing the yearly operation time and amount of work of the machinery leads to decreasing costs per unit. Increasing the yearly amount of work is limited by agrotechnical terms. The crop yield depends on the time and duration of field work, and affects the farm income. The methods and formulae to prognosticate the averageoptimum yearly operation time of farm's machinery, i.e. also farm's cereal-growing area was composed by the author, concerning biological, technical and economical factors and relations, affecting cereal production. Farm profit and profitability were used as optimization criteria.