Abstract. High biodiversity in grasslands is widely perceived to have a major role in maintaining or enhancing the amenity and cultural value of landscapes in Europe. In this paper, we focus mainly at community level, evaluating factors that appear to influence biodiversity at farm and landscape levels. In order to establish generic principles we examine the maintenance of biodiversity in terms of maintaining or enhancing functional diversity (FD). We define plant functional types (PFTs), groups of species having the same function and/or the same effect in the grassland ecosystem, species identified on the basis of plant traits. These traits reflect ecological responses to nutrient input and/or defoliation frequency, and they can also have an effect on ecosystem properties. We reviewed the literature, examining the relationship between several leaf and plant traits and principal ecological factors and, in turn, how these traits could influence the feed value of the grassland vegetation for herbivores. FD was determining as the range of relevant PFTs at community, farm and landscape levels. We propose a practical method of assessing agronomic value of semi-natural grasslands based on the determination of dominant PFTs by measuring traits in situ, or through using a trait database coupled to species abundance records. We then assess the relevance of the method for semi-natural grasslands subjected to several management practices.

Key words: biodiversity,grassland, defoliation, fertilisation

Absract. Maintaining and enhancing the biodiversity of the agriculturally utilised area has a high priority in environmental policy worldwide. Temperate grasslands in Europe make an important contribution to the biodiversity of agricultural landscapes. The species and community diversity of grasslands is a result of a traditional extensive grassland management interacting with a broad range of site conditions. Until the early decades of the last century, grassland sites were hardly ameliorated and the agronomic potential was generally low, depending on the fertility of the soils. Later on the production from grassland was markedly improved by regular fertilisation, by liming and by artificial drainage of wet sites. Correspondingly, the stocking rates and the cutting frequency increased. Thus, biodiversity strongly decreased, and unimproved species-rich swards only persisted on a low percentage of the total grassland area. The preservation of the remaining species-rich grassland is a primary goal of nature conservation. The continuation of traditional ways of grassland management that would best preserve biodiversity is often not compatible with the requirements of intensive livestock production. Therefore, this grassland is at risk of being abandoned from agricultural use. There is a need to identify and develop improved management measures that better integrate biodiversity and agronomy targets of species-rich grassland farming. In addition, compensation payments for farmers are required to support grass production on species-rich swards. Apart from the unimproved species-rich grassland, there is an increasing area of now de-intensified species-poor grassland which can be managed to increase biodiversity. Grazing at a low stocking rate seems to have the potential to facilitate the restoration of diverse swards and to support reasonable individual performances of the grazing animals.

R. Miljan¹, J. Miljan² and A. Leola^3
 
1Institute of Economics and Social Sciences, Estonian University of Life Sciences, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: Riina.Miljan@emu.ee
²Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51014,Tartu, Estonia; e-mail: Jaan.Miljan@emu.ee
³Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56, 51014 Tartu, Estonia

Abstract. In 1999 an investigation of the situation of Estonian cowsheds was carried out under the leadership of the Institute of Rural Building of the Estonian Agricultural University. The aim of the research was to determine the dominant building structures of cowsheds and find out what kind of technologies were used there. This research helped to clarify the situation and allowed to make proposals as to which problematic areas should get the attention of help funds of the European Union. In 2004 a similar survey was conducted about Estonian cowsheds. As a result of the research, we will be able to see what kind of changes have taken place during the past five years. It will also help us determine which problems still require the resources of the European Union in order to make the agricultural production more efficient.

Key words: dairy farm, cattle housing, milking systems, manure storage

Artificial neural network as an alternative to multiple regression analysis for estimating the parameters of econometric models
 
R. Põldaru¹, J. Roots¹ and A.-H. Viira^2
 
1 Institute of Economics and Social Sciences, Estonian University of Life Sciences, Kreutzwaldi 64, 51014 Tartu, Estonia;
e-mail: Reet.Poldaru@emu.ee, Jyri.Roots@emu.ee
²ARIB, Narva 3, 51009, Tartu, Estonia; e-mail: Ants.Viira@pria.ee

Abstract. In recent years, neural networks have been used for a wide variety of applications where statistical methods are traditionally employed. Neural nets offer the opportunity to create a model by using technology similar to the learning patterns of the human brain. The structure of artificial neural networks (ANN) is based on the human brain’s biological neural processes. Artificial neural networks provide a new approach to the problem of parameter estimation of nonlinear econometric models. This paper presents a comparison between neural networks and econometric approaches for estimation of parameters of an econometric model of grain yield. The aim of this study is to show that neural nets are a convenient econometric tool. The parameters were estimated on the basis of alternative variants of models. The analysis shows that artificial neural network models may be used for parameter estimation of the econometric models.

Key words: artificial neural network, econometric models, grain yield

Soil compaction and fertilisation effects on nutrient content and cellular fluid pH of spring barley (Hordeum vulgare L.)
 
E. Reintam¹, J. Kuht¹, H. Loogus², E. Nugis² and K. Trükmann^1
 
1Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Kreutzwaldi Str. 64, 51014 Tartu, Estonia; e-mail: endla.reintam@emu.ee
²Estonian Institute of Agricultural Engineering, Teaduse 13, 75501 Saku, Harjumaa, Estonia

Abstract. The main objective of this work was to investigate the effect of soil bulk density on nutrient (N, P, K) assimilation and on cellular fluid pH of spring barley (Hordeum vulgare L.) with different levels of fertilisation. Data were collected from the research fields of the Estonian University of Life Sciences (58^o23´N, 26^o44´E) with four different levels of soil compaction on sandy loam Stagnic Luvisol from 2001 to 2003. The soil was compacted by a tractor MTZ-82 (with loader; total weight 4.9 Mg) before spring sowing. Four levels of fertilisation (N0P0K0, N40P7K20; N80P14K40; N120P21K80) were applied using N20: P3.5: K10 fertiliser. Results of our experiments showed a high positive correlation between soil bulk density and cellular fluid pH (average r = 0.87) and negative correlation between soil bulk density and nutrient content (average r = –0.88) at highest rates of fertilisation (N80P14K40; N120P21K80) and positive correlation (r = 0.84) at lower rates of fertilisation (N0P0K0, N40P7K20) in the earing phase of barley. If the soil bulk density increased up to the level 1.56 Mg m^-3, there was a sudden increase of cellular fluid pH without fertiliser use. Use of fertilisers decreased the barley stress. A sudden increase of cellular fluid pH started after soil bulk density 1.61 Mg m^-3. The greatest impact of soil compaction was on nitrogen and potassium content in barley dry matter in all fertilisation levels. The nitrogen and potassium content in barley dry matter decreased up to 37% by high soil bulk density depending on fertilisation. The experiment showed that the higher decrease of nutrient content and the sudden increase of cellular fluid pH started at the same soil bulk density value.

Key words: soil compaction, bulk density, spring barley (Hordeum vulgare L.), nutrients (N, P, K), fertilisation, cellular fluid pH

Chlorophyll fluorescence characteristics of different winter wheat varieties (Triticum aestivum L.)
 
V. Šlapakauskas and V.Ruzgas
 
Lithuanian University of Agriculture, Studentø 11, Akademija, Kaunas district, LT-53067, Lithuania; e-mail: BO@nora.lzua.lt

Abstract. The objective of the study was to estimate the fluorescence level of newly developed winter wheat varieties. It was detected that the minimum (actual) fluorescence yield (F_t) and the maximum fluorescence yield (F_m), measured with every saturation pulse, as well as the quantum yield (Y) and rate of electron transport (ETR) in the illuminated leaves of the winter wheat varieties Ada and Alma were higher than in the control variety Širvinta. The fluorescence parameters of the variety Seda were weaker. Nevertheless, the grain yield of this variety was higher compared with the other varieties. The variety Seda is late ripening and more resistant to leaf diseases. Therefore, at the time of the experiment, the total area available for photosynthesis of the variety Seda was higher compared with the other varieties. The maximum electron transport rate in rapid light curve in the leaves of the wheat varieties Ada and Alma was measured to be 850 μmol m^-2s^-1 and for the variety Seda 800 μmol m^-2s^-1 of photosynthetically active radiation. In order to select plant breeding material using the chlorophyll fluorescence method more precisely, it is necessary to group the varieties or breeding lines according to the dates of maturity.

Key words: winter wheat, varieties, fluorescence characteristics   

Soil protection value of winter crops and reduced tillage on clay loams
 
A. Velykis and A. Satkus
 
Joniskelis Research Station of the Lithuanian Institute of Agriculture, Joniskelis, LT-5240 Pasvalys District, Lithuania;
Tel/fax: 370-71-38224; e-mail: joniskelio_lzi@post.omnitel.net

Abstract. Experiments to reduce soil physical degradation were carried out at Joniskelis Research Station of the Lithuanian Institute of Agriculture over the period 1998–2002. The soil of the experimental site is characterised as glacial lacustrine clay loam on silty clay (Gleyic Cambisol). The following was investigated: Factor A. Crop rotations with different proportions of winter and spring crops (1. Without winter crops; 2. Winter crops 25%; 3. Winter crops 50%; 4. Winter crops 75%; 5. Winter crops 100%), growing annual and perennial grasses, spring and winter wheat, triticale, and barley. Factor B. Soil tillage systems: 1. Conventional (primary soil tillage was performed by ploughing); 2. Sustainable (after grasses the soil was ploughed, after other preceding crops the soil was loosened without inverting the topsoil). Our experimental evidence suggests that increasing winter crops in the crop rotation reduced compaction of the topsoil from high to moderate, maintained up to 37.3% of higher productive moisture reserves, improved water to air ratio, and increased the crop rotation productivity up to 44.7%. The application of reduced primary tillage in a sustainable system had persistence of high soil compaction and 8.0% lower air-filled porosity at the bottom of the topsoil, but the whole topsoil reached physical maturity more evenly in the spring. The grain yield of cereals was 6.4% lower compared with the yield after conventional soil tillage. On these clay loam soils, spring cereals were more sensitive (poorer performance) to reduced soil tillage compared with winter cereals.

Key words: clay loam Cambisol, crop rotations, soil tillage, winter crops, physical properties, crop yield