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In the overview nomenclature, properties, distribution, productivity and usage of ryhky soils, as the Year 2021 Soil of Estonia, are treated. As synonyms of the name ryhky soils, also the names pebble rendzina and gravelly soils have been used in Estonian Soil Classification (ESC). In overview, the main attention is paid to dry, fresh and moist rich in coarse calcareous material mild-humuous (mull-type) soils. After WRB these soils may be characterized by prefix qualifiers as calcaric or eutric, skeletic or hyperskeletic and rendzic or mollic CAMBISOLS, LITHOSOLS or REGOSOLS, whereas all of them have endogleyic versions as well. The wet and eroded ryhky soils have been excluded from the overview as their properties depend not so on the coarse calcareous earth content as on feeding their soil water or water erosion. The area of ryhky soils forms 6.3% from whole Estonian soil cover and 11.1% from the arable land. The main criteria of ryhky soil species' determination are calcareousness, content and shape of coarse soil fragments, and water regime of soil cover. By ESC six soil species have been determined, from which three ones have endogleyic character. The fine earth texture of ryhky soils is mainly loam. From the coarse fractions, the indicative role belongs to the small stones (ryhk, pebble and shingle). The morphology, humus status and suitability of ryhky soils for management are treated on the level of soil species independence of land use (arable, forest or grassland). [ABSTRACT FROM AUTHOR]

The work, dedicated to the eroded soil i.e. the year 2020 soil of Estonia, consists of two-part. In Part I the general overview (a) the regularities of erosion processes and their forming conditions in the soil cover, and (b) the agro-ecological properties and nomenclature of formed erosion-affected soils (EAS), are treated. Totally in the Estonian soil classification (ESC) 11 eroded and 3 deluvial (colluvial) soil species have been determined. For the main criteria of eroded soils' determination is (a) the intensity or stage of erosion, and (b) the calcareousness of soil cover, but deluvial soils (a) the soils' water regime and (b) the thickness of formed deluvial humus horizon. In this part also the determination criteria of erosion-prone soils and the agronomic quality of EAS are analysed. In Part II the historic overview about scientific researches dedicated to the study of influenced by erosion soils during the last century in Estonia. In this overview, the main thematic issue and the role of leading scientists on researches of most actual problems are presented. The most important themes during this period were: (a) the elaboration suitable for local conditions EAS classification and methods for their field researches; (b) the distribution of EAS in Estonia; (c) the studies upon forming, composition and status of EAS-s; (d) forming databases on essential properties of EAS-s and derived from this the rules of their ecologically sustainable use, and finally (e) the international aspects of Estonian EAS presentation and local researches. [ABSTRACT FROM AUTHOR]

Soil respiration resulting from microbial and root respiration is a major component of the forest carbon cycle. The response of soil respiration to varying environmental factors (soil temperature and soil moisture) was studied in a Norway spruce chronosequence composed of four age classes (4, 27, 36, and 84 year old) on Gleyic Podzol. Soil respiration was measured monthly with closed dynamic chamber system, soil temperature and soil moisture were measured simultaneously. Mean soil respiration rate averaged over three years was 3.3 μmol CO2 m-2s-1, ranging from 0.6 to 5.4 μmol CO2 m-2s-1, with the maximum occurring in August and the minimum in December. Stand age had a significant effect on soil respiration: the highest respiration rate was found in 27-year-old stand. Over three years an exponential relationship between soil respiration and soil temperature accounted for 68-81% of the seasonal variation, Q10 (the factor by which the respiration rate differs for a temperature interval of 10 °C) for the individual stands ranged between 4.4 and 5.4. The influence of soil moisture content on soil respiration was weak and revealed in dry conditions only. The results of this study can be used to help understand and predict the effect of harvest on soil respiration and how the respiration might respond to changing climate conditions.

In present work the composition and properties of three experimental areas' (Jõgeva -- JKA, Kuusiku -- KKA and Olustvere -- OKA) soil covers were analyzed in concordance with soil forming (pedo-ecological) conditions and land management practice. The soil cover of JKA is relatively homogenous, whereas its dominant soil species are eluviated (KI) and leached (Ko) brown soils (altogether 83%) and the dominant soil texture of humus cover (topsoil) is slightly pebble loam (90%), as for the rest of JKA the texture is sandy loam. From the 8 associated soil species, the most distributed are gleyed eluviated (KIg) brown soils (~10%). The differences in soil cover composition between three separately studied arable land massifs of JKA were not significant. The soil cover of KKA experimental area is much more heterogeneous, as the contrast by soil genesis was 5 stages and by soil moisture conditions 4 stages. The soil texture of KKA is also approximately two to three times more heterogeneous than others (JKA and OKA,) as in its humus cover the loamy sands (38%), sands (33%) and loams (29%) were found. The character soil species of the KKA are leached gley soils (Go), Ko, KIg and pebble rendzina (K), which form together ~75% from total area and therefore may be classified as dominant soils. With them 10 soil species with variable pedogenetic properties are associated. For receiving suitable areas for experimental fields, the KKA total area was divided into separate (by soil cover more homo- geneous, but different from each other by dominant soil species) three arable land massifs: (I) with dominating Ko, K and strongly skeletal pebble rendzina (Kr), (II) where the Kr and K are dominants and (III) with dominating drained Go and KIg. In the soil cover of OKA, the dominant soil species is pseudopodzolic soil (LP, 86%) and dominant humus cover texture is sandy loam (76%), whereas the stage of heterogeneity is very similar to JKA. If JKA is by soil cover composition and properties representative to central Estonian pedo-ecological conditions, then OKA to South Estonian and KKA to North Estonian pedoecological conditions. In the work by three research areas (JKA, KKA, OKA) and by their seven arable land massifs, besides the soil cover composition and pedo-ecological conditions, the soil cover pedodiversity, contrast of presented in soil cover soils, humus cover types and agrochemical status are analyzed. From the aspect of dominant soils, the fabric of soil profile and characteristic on soil humus status (humus concentration, thickness and humus stocks of A-horizons) are also treated. Soils of JKA have high environmental protection value due to neutral or slightly acid reaction, optimal humus content, great cation exchange capacity, sufficient solum thickness and good properties of subsoil. The environmental protection ability of KKA soil cover is decreased due to high content of rock fragments in soil and low biological activity of epipedons. In case of OKA, the low environmental protection value results from sandy topsoil texture, acidic soil reaction, and low humus content and stock. [ABSTRACT FROM AUTHOR]

Soil respiration resulting from microbial and root respiration is a major component of the forest carbon cycle. The response of soil respiration to varying environmental factors (soil temperature and soil moisture) was studied in a Norway spruce chronosequence composed of four age classes (4, 27, 36, and 84 year old) on Gleyic Podzol. Soil respiration was measured monthly with closed dynamic chamber system, soil temperature and soil moisture were measured simultaneously. Mean soil respiration rate averaged over three years was 3.3 µmol CO2 m-2 s-1, ranging from 0.6 to 5.4 µmol CO2 m-2 s-1, with the maximum occurring in August and the minimum in December. Stand age had a significant effect on soil respiration: the highest respiration rate was found in 27-year-old stand. Over three years an exponential relationship between soil respiration and soil temperature accounted for 68--81% of the seasonal variation, Q10 (the factor by which the respiration rate differs for a temperature interval of 10 °C) for the individual stands ranged between 4.4 and 5.4. The influence of soil moisture content on soil respiration was weak and revealed in dry conditions only. The results of this study can be used to help understand and predict the effect of harvest on soil respiration and how the respiration might respond to changing climate conditions. [ABSTRACT FROM AUTHOR]