The efficient functioning of drainage objects depends on a number of accidental factors: natural and climatic conditions, the quality of drainage technologies and their exploitation, as well as the peculiarities of drained land use. Drainage reliability may be evaluated in view of the following indices: mean quantitative values, fluctuation peculiarities, interrelations and dependence of the indices. One of the indices, determining the reliability of drainage objects, is the drainage operation time to failure - the longer this time, the more reliable the drainage is from the point of view of exploitation. The paper deals with one of the most important reliability indices of drainage systems - it's operating time to failure. The indices of drainage functioning until its failure have been defined on the basis of probability theory and mathematical statistics. The distribution regularities have been established for the drainage object under different land-reclamation conditions. This might help to determine the failure probability, a certain age as well as to foresee the time and extent of repair works.

The goal of this study was to investigate the use of body reserves, energy balance and fertility parameters at the beginning of lactation in first-parity cows bred in Estonia.

Experiments were performed to test the agronomic potential of kura clover in the seed mixtures with diminished seeding rates. During the seeding year a very slow establishment of kura clover (sown with perennial ryegrass) was observed: kura clover gave up to 7% of the total DM yield. The kura clover plants survived winter 2000/2001 well, but the distribution in the sward was not observed in the second year. The established grass sward density was rather high in the seeding year (around 10 000 tillers per square m) in 2000. In 2001, the white clover content increased to 80% of the DM yield but at the same time the grass sward density was decreased to 2900 tillers per square m. The kura clover plants are characterised by high proportion of leaves to stem and high nutritional characteristics with protein concentrations ranging between 19 and 23% as well as the neutral detergent fibre (NDF) concentrations between 24 and 38%. The experiments showed that the strains of Rhizobium bacteria required for kura clover do not naturally occur in Estonian soils and proper inoculation of kura clover seeds before planting is critical to get well-nodulated and persistent plants.

To study the organic matter digestibility of feeds 22 in vivo and in vitro digestion experiments were carried out by using DAISY II filter bags system in the Eerika Experimental Farm of the Estonian Agricultural University in 1997-2001. In the in vivo experiments 4 rams and special boxes were used. The in vitro experiments were carried out and the chemical composition of feeds was determined in the laboratory of the Department of Animal Nutrition in the Institute of Animal Science by methods generally recognized in the EU. The objective of the study was the comparison of organic matter digestibility of feeds measured by in vivo methods, by DAISY II filter bags method and of that calculated by acid detergent fibre or neutral detergent fibre.

Activation of lypolysis during milking normally results from faulty design and instalation, and inadequate maintenance of milking equipment, and is associated with excessive air intake into the system, causing turbulence. Majority of pipeline milking systems used in Estonian dairy farms have been instaled in 70s and 80s. Their mounting does not meet the requirements of ISO 6690 and 5707. In recent years, besides installing of new milking equipment, the reconstruction of old ones has been started. There is little information on the effect of that kind of reconstruction on raw milk quality. In this study, the effect of three factors on induced lipolysis were investigated on original laboratory experimental equipment. The parameters of studied factors - the time of agitation the intensiveness of agitation and the rate of aeration - were changed independently. A preliminary study showed these three factors. Aeration rate was mainly responsible for the increased FFA content of raw milk.

Balance of nitrogen, phosphor and potassium content in four rotations of sugar beets (in respective periods of 1965-1973; 1974-1982; 1083-1991 and 1992-2000) was established at the Rumokai Research Station of the Agricultural Institute of Lithuania. Extended crop rotation of nine fields included two fields of winter wheat or rye (22.2%), two fields of sugar beets (22.2%), two fields of barley (22.2%), one field of perennial grass, i.e. red clover and meadow timothy of the first year use (11.1%), one field of perennial grass - red clover and meadow timothy - of the second year use (11.1%) and one field contained vegetated fallow with the drilled mixture of vetch and oat for green fodder (11.1%). Organic-mineral fertilisation system was employed in the process of crop rotation.

The paper presents some data collected for various purposes on phenomena, which took place in drainage channels. The data shows a certain one-direction trend of development of these phenomena when slopes of channels are covered with woody vegetation: the intensity of sedimentation of channel's bottom slowed down (Fig. 1); cross section area blocked up by snow decreased (Table 1); concentrations of biogenic and organic (BOD) matter did not show the worsening of water quality (Table 2 and 3). In the most channnels the losses of hydraulic conductivity occuring because of woody vegetation are usually compensated by conductivity reserve of a bigger cross section area caused by a rather large depth of subsurface drainage systems.