Raimo Kõlli

European Humus Forms Reference Base

In Europe an abundance of humus taxonomies exists starting with early approaches in the late 19th century. Frequently used in an international context, they do not cover all site conditions in the European area. Although having basic concepts and general lines, the European (and North American, Canadian) classification systems differ in important parameters used for the description and classification of humus forms. These discrepancies result in incongruities, so require adjustments when exchanging partially compatible soil data, even between nearby countries. In 2003, 26 European specialists in humus forms met in Trento (Italy) and decided to formulate rules of classification based on morphogenetic descriptions and diagnostic horizons, adapted to European ecological conditions. Taking into account old and new European and North American systems of humus forms classification, six main references (Anmoor, Mull, Moder, Mor, Amphi and Tangel) were defined, each of them further dividing into detailed categories. This inventory assigned a strong discriminatory power to the action of the pedofauna. Both semiterrestrial (anoxic) and terrestrial (aerated) topsoils were classified. The descriptors of the diagnostic horizons were conceived in accordance with the spirit of recent international soil classifications. Assigning an “ecological value” to each main humus form along a gradient dividing those characterized by accumulation of poorly transformed organic matter, from very biologically active forms degrading and incorporating all organic remains, this European system of classification avoids a hierarchical structure and allows an elastic approach open to additional ecological contributions and renditions.

Effect of Cut Plant Residue Management and Fertilization on the Dry-Matter Yield of Swards and on Carbon Content of Soil

The goal of this research was to study the impact of cut plant residues, returned to or removed from the grassland sward, on the dry-matter yield of swards and on the organic carbon (Corg) concentration of soil. The experiment was carried out during 2004–2008. The variables of the experiment were (i) sward type: turfgrass sward (Festuca rubra rubra and Poa pratensis) and grass–clover sward (Phleum pratense, Lolium perenne, and Trifolium repens) and (ii) treatment of residues: the cut plant residues were returned (RRT) to the plots or removed (RRM) from the plots after the mowing. The fertilizer treatments were as follows: N0P0K0, N80P11K48, N160P22K96, and N400P56K240 kg ha−1 for the turfgrass sward and N0P0K0 and N80P26K50 kg ha−1 for the grass–clover sward. The Corg and Ntot concentrations in the 20-cm soil layer were measured at the beginning and at the end of the experiment at depths of 0–5 cm and 5–20 cm. Nitrogen was returned as plant residues to the grass–clover sward in treatment N0P0K0 at 190 kg ha−1 and N80P26K50 at 204 kg ha−1 and consequently the returned cut plant residues increased the yield by 31% and 22%, respectively. The amount of N returned as residues to turfgrass sward was 31–236 kg ha−1 but it had no significant influence on the sward dry-matter yield. During the 5 years of the experiment the Corg content in 0- to 5-cm soil layer of grass–clover sward in treatment RRT increased by 42.9% and in RRM by 32.0% as an average of both fertilization treatments. At the depth 5–20 cm the Corg concentration did not change in treatment RRT, but in treatment RRM with fertilization the Corg concentration decreased by 8.2%. In turfgrass soil the Corg concentration increased in RRT treatment by 21.6% and in treatment RRM by 7.2% during 5 years. In the lower soil layer the concentration of Corg decreased with removal and return of plant residues. The fertilization did not influence the changes of Corg concentration in turfgrass swards soil.

Formation of the chemical composition of Histosols and histic soils in the forest lands of Estonia

The formation and vertical distribution of the chemical properties of fen (group I, five research areas) and transitional bog (group II, eight research areas) Histosols, and situated depressions of mineral landscape Histic Gleysols (group III, six research areas) and Histic Podzols (group IV, seven research areas) soil covers were studied. As a benchmark in the comparative analysis of Histosols, we used the 20 cm epipedon peat layers of eutrophic moderately acid (I) and mesotrophic very strongly acid (II) types. The thickness of histic soil epipedon peat varied from 10 to 30 cm and was classified as slightly acid peaty mull (IIIa) or strongly acid peaty moder (IIIb), and as very strongly acid peaty mor (IV). In forming the epipedon of the forest floor, aqua regia (mixture of hydrochloridic and nitric acids, 3:1)-extractable Fe, Cr, Al, Pb and Ni accumulated to a great extent (accumulation coefficient>2.5), and S, Na and Hg accumulated to a medium extent (accumulation coefficient 1.2–2.0); the amounts of Zn, K and Mn decreased to a great extent (accumulation coefficient<0.5), and those of Mg and P to a medium extent (accumulation coefficient 0.6–0.8); levels of Ca, Cu and Cd remained practically unchanged. Comparison of Histosol subsoil and substratum peats with a Histosol epipedon demonstrates considerable accumulation of Mn, Pb, Cd, Zn, Hg and Na in the thin (20 cm) superficial peat layer of mires.

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.

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.