Alar Astover

Changes in agricultural land use and in plant nutrient balances of arable soils in Estonia

Abstract The aim of the present study was to assess the impact of changes in agricultural land use and in the plant nutrient balances on the degradation of soils in Estonia. The plant nutrient balances of arable soils in Estonia were calculated at the national level. After the re-establishment of the independence of Estonia, in the transition to market economy, agricultural production has undergone a drastic decline. Agricultural land use has declined most of all in the regions with low soil fertility. Decreased and low-input agricultural production has reduced pressure on the surrounding environment but owing to the inadequate use of fertilizers, the balance of the main plant nutrients is at present negative. In the 1990s, crop production has occurred largely at the expense of soil resources. Current agri-environmental policy should be supplemented with measures for preventing degradation of soils due to the depletion of plant nutrient reserves of arable soils.

Assessment of abandoned agricultural land resource for bio-energy production in Estonia.

Abstract The current study locates and quantifies abandoned agricultural areas using the Geographic Information System (GIS) and evaluates the suitability of abandoned fields for bio-energy production in Tartumaa (Tartu County) in Estonia. Soils of abandoned areas are generally of low quality and thereby limited suitability for crop production; as a result soil–crop suitability analyses could form the basis of knowledge-based bio-energy planning. The study estimated suitable areas for bio-energy production using willow (Salix sp), grey alder [Alnus incana (L.) Moench], hybrid aspen (Populus tremuloides Michx.×Populus tremula L.), reed canary grass (Phalaris arundinacea L.), and Caucasian goats rue (Galega orientalis Lam.) in separate plantations. A combined land-use strategy is also presented as these crops are partially suitable to the same areas. Reed canary grass and grey alder have the highest energy potentials and each would re-use more than 80% of the available abandoned agricultural land. Energy grasses and short-rotation forestry in combined land-use strategy represents the opportunity of covering approximately a quarter of countys annual energy demand. The study estimates only agronomic potential, so further bio-energy analysis should take into account technical and economic limitations. Developed framework supports knowledge-based decision-making processes from field to regional scale to achieve sustainable bio-energy production.

Soil compaction effects on soil bulk density and penetration resistance and growth of spring barley (Hordeum vulgare L.)

Abstract The weight of the tractor is not the only factor affecting soil compaction. Soil-management practices, such as the use of fertilizers and pesticides, also affect soil properties through an increased number of overriding. The aim of the current study was to investigate compaction effects on soil physical properties, such as dry bulk density and penetration resistance, and the growth of spring barley (Hordeum vulgare L.) as a monoculture. The five-year experiment was conducted on the Estonian University of Life Sciences’ research field at Eerika, near Tartu in 2001–2005. The soil of the experimental site is sandy loam Stagnic Luvisol. The treatments included were no compaction, one pass, three passes, and six passes. All passes were track-by-track. Measurements of soil and plant were made in the earing phase of barley and measurements of yield in the maturity phase of barley. The compaction treatment was conducted using an MTZ-82 tractor (total weight 4.84 Mg). Neither fertilizers nor herbicides were used. 5 years after compaction distinguishable subsoil and topsoil compaction was detected. Soil deformation increases with the number of passes; in the case of six passes soil bulk density increased by 0.15 Mg m−3 and penetration resistance by 3 MPa. However, there were no significant differences in the soil bulk density and penetration resistance between treatments compacted with one and three passes. The effect of compaction on soil bulk density was higher when the soil was compacted under wet conditions. Compaction decreased the quantity of barley shoots, their phytomass, and grain yield by more than 80%. In the second year of the experiment the dry weight of above ground biomass decreased by almost three times and shoots’ density by 1.5 times, compared with the first year results. In the third year of the experiment the biomass, plant density, and grain yield of barley were stabilized and no further decreases were detected in the following two experimental years. The results from the experiment revealed that even a low weight tractor can induce subsoil compaction and a high decrease of plant productivity by repeated passes over time.

The effects of pure and undersowing green manures on yields of succeeding spring cereals

Abstract A field experiment was conducted in 2004–2006 to investigate the effect of green manure treatments on the yield of oats and spring barley. In the experiment, different green manure crops with undersowing and pure sowing were compared for amounts of N, C, and organic matter driven into soil and their effect on cereal yield. The spring barley field had a total of 41.7–62.4 kg N ha−1 and 1.75–2.81 Mg C ha−1 added to the soil with straw, weed, and roots, depending on the level of fertilisation; with red clover, and both common and hybrid lucerne undersowing, with barley straw and roots, the values were 3.45–3.96 Mg C ha−1 and 139.9–184.9 kg N ha−1. Pure sowings of these three leguminous green manure crops had total applications of 3.37–4.14 Mg C ha−1 and 219.7–236.8 kg N ha−1. The mixed and pure sowing of birds-foot trefoil provided considerably less nitrogen and carbon to the soil with the biomass than with the other leguminous crops. Application of biomass with a high C/N ratio reduced the yield of the succeeding spring cereals. Of the green manures, the most effective were red clover and both common and hybrid lucerne, either as undersowing or as pure sowing. Undersowings with barley significantly increased the N supply for the succeeding crop without yield loss of the main crop compared with the unfertilised variant. Compared with ploughing-in of green manure in autumn, spring ploughing gave a 0.2–0.57 Mg ha−1 larger grain yield.

Efficiency of Estonian grain farms in 2000-2004

The aim of this study is to analyse the efficiency of Estonian grain farms after Estonia’s transition to a market economy and during the accession period to the European Union (EU). The non-parametric method Data Envelopment Analysis (DEA) was used to estimate the total technical, pure technical and scale efficiency of Estonian grain farms in 2000–2004. Mean total technical efficiency varied from 0.70 to 0.78. Of the grain farms 62% are operating under increasing returns to scale. Solely based on the DEA model it is not possible to determine optimum farm scale and the range of Estonian farm sizes operating efficiently is extensive. The most pure technically efficient farms were the smallest and the largest but the productivity of small farms is low compared to larger farms because of their small scale. Therefore, they are the least competitive. Since pre-accession period to the EU, large input slacks of capital have replaced the former excessive use of labour and land. This raises the question about the effects on efficiency of the EU’s investment support schemes in new member states.

Impact of Long-Term Agricultural Management and Native Forest Ecosystem on the Chemical and Biochemical Properties of Retisols’ Organic Matter

The objective of the chapter is to assess the impact of long-term fertilization on biologically active substances in arable Fragic Glossic Retisols and to compare received results with corresponding native forest soil. The analysis of interactions of chemical and biochemical compounds in soils was based on soil samples taken from the long-term field experiment (crop rotation, as cultivated ecosystem, with application of mineral and organic fertilizers: potato, spring wheat, spring barley) and from the forest soil (as native ecosystem). The relationship between quantities of chemical and biochemical compounds in arable soils’ organic matter and in the yield of cultivated plants was greatly influenced by the use of mineral and organic fertilizers. The contents of phytohormone indole-3-acetic acid (IAA), participating in nitrogen cycle enzymes (urease and nitrate reductase), and different forms of nitrogen and organic carbon in soils have a marked effect on the crop yield. Arable soil in rotation without organic fertilizers treated with mineral fertilizer (120 kg N ha−1) revealed the highest increase of nitrate reductase activity, and the highest concentration of IAA, however, the lowest activity of urease. Therefore, mineral fertilizer in comparison with farmyard manure and alternative organic fertilizers created the most suitable conditions for the crop yield increase. The highest activity of urease in forest soil is closely associated with the concentration of biochemically available (dissolvable in water) organic carbon.

Measuring and predicting soil moisture conditions for trafficability

ABSTRACT The main cause of loss of soil structural stability is vehicle operation on unpaved wet surfaces. Unfortunately, there is a lack of continuous soil moisture data in predicting trafficable conditions. To measure changes in soil moisture conditions in real time, Percostation (Adek) sensors were installed in sandy loam Stagnosol soil at different depths. Problems with soil trafficability can be expected at the plastic limit, and the soil is unable to support vehicle operations at the liquid limit in such soils. The maximum water-holding capacity of the soil is 32%, the field capacity is 25%, the plastic limit is 22%, and the liquid limit is 30%. With rainfall of more than 10 mm d−1, the moisture content reached the plastic limit in the upper 25 cm of soil. The average increase in the soil moisture content after more than 10 mm of rain was 1–2.5% in a time frame of 2–3 hours. After rain, the previous soil moisture level was obtained within 2 to 3 days in the vegetation period. Measurements also allowed soil water balance and evapotranspiration modelling data to predict soil moisture conditions with an accuracy of one day but failed to predict in a shorter period.

Accumulation of metallic elements into the superficial peat layer of mires and wet mineral soils of Estonian forest land / Akumulacja metali w powierzchniowej warstwie gleb torfowych i wilgotnych glebach mineralnych ekosystemów leśnych Estonii

Abstract This article studied the extent of accumulation of aqua regia extractable metallic elements (Al, Mg, Pb, Zn, Hg, Cd) into peaty (histic) epipedon (EP) of fen soils, transitional bog soils, peaty gley soils and peaty podzols. The accumulation coefficients (Kac) of the elements in EP were estimated in relation of forest floor (FF, as an input) as a comparison to deeper levels (SS, as a past background). The study revealed that the extent of accumulation and its order depend on soil (peat) type or pedo-ecological conditions of peatification. In the forming of EP from FF, the concentrations of Al and Pb were increased on an average 2.5-5.0 times, but that of Hg increased significantly only in peaty soils (on an average 1.5-1.6 times). The contents of Zn were significantly decreased (Kac 0.1-0.5) in all soil groups. The comparison of EP peats concentrations with SS data demonstrated a considerable accumulation of Pb, Cd, Zn and Hg into thin (~20 cm) superficial peat layer. Streszczenie Z wykorzystaniem wody królewskiej badano stopień akumulacji metali (Al, Mg, Pb, Zn, Hg, Cd) w epipedonie torfów wysokich (EP), torfów przejściowych, oglejonych glebach torfowych oraz zabagnionych glebach bielicowych. Współczynnik akumulacji metali (Kac) w EP oszacowano w zależności od runa leśnego (FF, jako wkład) i w porównaniu do głębszych poziomów (SS, jako tło przeszłości). Stwierdzono, że stopień akumulacji metali jest uzależniony of typu gleby (torfu) oraz jej właściwości. W powstałym EP z FF stężenia Al i Pb zwiększyły się średnio 2.5-5.0 razy, natomiast Hg istotnie jedynie w glebach torfowych (średnio 1.5-1.6 razy). Istotnie zmniejszyły się (Kac 0.1-0.5 razy) zawartości Zn we wszystkich glebach. Porównując zawartości metali w EP z SS stwierdzono znaczącą akumulację Pb, Cd, Zn i Hg w (~20 cm) powierzchniowej warstwie torfowej.

Decision support system for agricultural land use and fertilisation optimisation: a case study on barley production in Estonia

The success of the decision support systems, developed within GIS with application of different models, depends on the quality of initial data and the models themselves as well as on the possibilities of their linking. The aim of the present study was to analyse the application of different agro-economic models in a computer-based decision support system, developed for optimisation of agricultural land use and fertilisation, on the example of barley production of Kullamaa rural municipality in Estonia. The algorithms used in the agronomical models were obtained from the regression analysis of numerous field experiments. The calculated new agronomical values serve as a basis for the application of economic models. GIS and modelling remain as two separate systems with the capacity for information exchange between them. Profitability of barley cultivation varied in a very broad range in the study area. The optimal fertiliser amounts established for each field allow increasing crop productivity in the region and at the same time preventing environmental pollution due to production intensification. The proposed decision support system can be further supplemented by several agro-economic models and implemented throughout Estonia.;