Haplic Podzol Research Articles

Effects of thermal and hydrophysical properties of sandy Haplic Podzol on actual evapotranspiration of spring wheat

Abstract The objectives of the research were to: (1) assess the strength of relationships between the soil thermal and hydrophysical properties, (2) evaluate the strength of association of evapotranspiration of spring wheat crop with soil thermal and hydrophysical properties, and (3) estimate the ranges of the thermal and hydrophysical properties of the sandy Haplic Podzol during the growing period of spring wheat in 2022. The study included instrumental simultaneous measurements of meteorological data, soil water retention curve, soil moisture content (SMC) and thermal properties. Actual evapotranspiration was calculated according to the Allen equation. Spearman’s rank correlation coefficients showed that the increase in SMC from 0.10 cm3 cm−3 to 0.26 cm3 cm−3 resulted in a significant increase in thermal conductivity (r = 0.81, p < 0.001), volumetric heat capacity (r = 0.93, p < 0.001) and thermal diffusivity (r = 0.94, p < 0.001). Actual evapotranspiration also rose with the increasing SMC (r = 0.91, p < 0.001) and matric water potentials (r = 0.61, p < 0.05). As a consequence of the changes in SMC, the Spearman’s rank correlation coefficients supported the strong positive relationships of actual evapotranspiration with volumetric heat capacity (r = 0.97, p < 0.001), thermal conductivity (r = 0.96, p < 0.001) and thermal diffusivity (r = 0.96, p < 0.001). Pearson correlation coefficients also supported the strong input of thermal inertia to the actual evapotranspiration (r = 0.88, p < 0.01). During the whole period of observations, actual evapotranspiration varied from 0.05 to 0.59 mm hr−1, soil thermal conductivity – from 0.225 to −1.056 W m−1 K−1, volumetric heat capacity – from 1.057 to 1.889 MJ m–3 K−1, heat diffusivity from 0.189 to 0.559 mm2 s−1, and thermal inertia – from 516 to 1412 J m−2 K−1 s−0.5.

Biodiversity in the Rhizosphere of Selected Winter Wheat (Triticum aestivum L.) Cultivars—Genetic and Catabolic Fingerprinting

The main goal of the study was to determine the biodiversity of bacteria and their metabolic profile in the rhizosphere of four winter wheat (Triticum aestivum L.) varieties (Hondia, Nordkap, Rotax, Tytanika) cultivated in Haplic Podzol soil in a no-tillage system. Two techniques, i.e., next generation sequencing (NGS, meta-barcoding of 16S rRNA community) and community level physiological profiling (CLPP), were applied to obtain a holistic picture of biodiversity. The basic soil chemical parameters (acidity, redox potential, carbon content, forms of nitrogen, and phosphorus) were also determined. It was found that the rhizospheric microbiome (at the genus level) of cv. Hondia and Rotax were significantly different from that present in the other cultivars studied. The CLPP technique demonstrated that microbial metabolic activity depended on both the type of substrate and wheat cultivars. Carbohydrates and carboxylic acids were the most easily utilized compounds in all rhizospheric soils. The principal component analysis (PCA) evidenced that the rhizospheric soils of Rotax and Nordkap were characterized by a higher functional activity (strong correlation with the Shannon-Wiener index, the Richness index, and utilization of hydrocarbons) than those of Hondia and Tytanika.

Effect of Natural Aging of Biochar on Soil Enzymatic Activity and Physicochemical Properties in Long-Term Field Experiment

The effect of different rates of biochar on selected soil properties and enzymatic activity 48, 60, and 72 months after biochar application to soil was investigated. Soil enzymatic activity (dehydrogenase—ADh; phosphatase—Aph; urease—AU), the organic carbon content (TOC), the total nitrogen content (Nt), the mineral nitrogen content (NH4+, NO3−), and soil pH were determined. The study was conducted on Haplic Podzol originating from glaciofluvial fine-grained loamy sand. Biochar was applied to soil under winter rye (Secale cereale L.) at rates of 10 (BC10), 20 (BC20), and 30 t ha−1 (BC30). Plots with biochar-unamended soil were the control treatment (BC0). The pH, TOC, and Nt content in the biochar-amended soil were higher compared to the control soil. A broader C:N ratio was found in the BC0 soil compared to BC10, BC20, and BC30. With increasing biochar rate, the content of the ammonium nitrogen form (NH4+) decreased and was statistically lower than in the control soil (BC0). The soil in the BC20 and BC30 treatments was characterized by the highest content of NO3-, whereas the lowest nitrate nitrogen content was found in the control soil (BC0). Biochar application increased soil enzymatic activity. Dehydrogenase activity increased with increasing biochar rate. As far as phosphatase and urease activity is concerned, a similar relationship was not observed. In this case, the soil amended with biochar at a rate of 20 t ha−1 (BC20) was characterized by the highest phosphatase and urease activity.

Methanogenesis and aerobic methanotrophy in arable soils contaminated with cadmium

Soil is a non-renewable environment in which, depending on the prevailing O2 conditions, two opposite processes – methanogenesis and methanotrophy - may take place. The rates of the processes may result in soil acting as a sink or a source of methane (CH4). Due to agricultural practices, heavy metals may accumulate affecting soil microbial processes. We tested the effect of cadmium (Cd) contamination on CH4 emission and uptake in three mineral soils (Eutric Cambisol, Haplic Podzol, Mollic Gleysol). Additionally, in the methanotrophy study, different soil moisture levels (pF 0; 2.2; 3.2) were studied. Based on the European annual and maximum limits, soils were polluted with cadmium in four doses (per dry soil mass): 0.048 mg Cd kg−1 (and its five-fold higher value) and 3.00 mg Cd kg−1 (and its five-fold higher value). The results showed that all tested soils produced and consumed CH4. Methane production rates were not significantly changed by the presence of the cadmium (except annual five-fold Cd dose in Podzol). In methanotrophy study, soil moisture was stronger regulator of CH4 oxidation (p < 0.05) than Cd pollution which effect depended on the soil type, Cd dose and pF level. CH4 was completely consumed in Cambisol (only at pF 0 with the rate significantly different from the rates at pF 2.2 and 3.2) and in Gleysol (at pF 0; pF 2.2; the CH4 oxidation rates were significantly different among all tested moistures with annual Cd dose), but this process was delayed after the application of the higher Cd doses. Among the tested soils, only the Podzol oxidized the added CH4 under all tested moisture levels (with the rate significantly different at pF 2.2 wit annual Cd dose), while Cd addition delayed CH4 uptake as well. In the Podzol, CH4 consumption was inhibited only by the highest Cd dose at low moisture (pF 3.2).

Impact of selected waste applications on soil compaction

In the years 2014–2017, a field experiment was carried out, in which two types of waste were applied to soil. One of them was mineral waste – carboniferous rock from a hard coal mine, and the other – organic waste – post-fermentation sludge from agricultural biogas-producing plant. The experiment was an example of an action, in which soil management was associated with their drainage effects on the soil. The waste was applied to the light soil of low utility value, included in the V bonitation class (in polish soil quality classification) and the 6th complex of agricultural suitability (weak rye). According to the WRB classification, it was Haplic Podzol (PZha) developed from the post-glacial sand. The aim of the study was to analyze changes in soil compaction caused by a single introduction of waste. During the four-year study (2014–2017), the durability of these changes was also observed. It was found that the best effects of reducing the soil compaction were obtained as a result of the combined application of two wastes: carboniferous rock and post-fermentation sludge. Introduction of waste into the soil was also permanent, as differences resulting from the soil management continued in the fourth year of the experiment.

Soil properties and not high CO2 affect CH4 production and uptake in periodically waterlogged arable soils

Several studies related to CH4 cycling focus on the effect of elevated atmospheric CO2 levels on soil methanogenesis and methanotrophy. However, periodically waterlogged soils are characterized by much higher CO2 concentrations, while aggregates forming in arable soils due to traditional cultivation may be a natural CH4 source for low-affinity methanotrophs. We present a comprehensive laboratory investigation into both methanogenesis and methanotrophy in three different soils under ambient and high CO2 concentrations. The tested materials were agricultural soils widely distributed in Europe: Eutric Cambisol, Haplic Podzol and Mollic Gleysol with determined properties: Corg, Ntot, clay, silt, sand, pH, NO3−, NH4+. We conducted two independent experiments on methanogenesis (flooded conditions) and methanotrophy (non-flooded conditions). All samples for both studies were divided into three sets which differed in the initial CO2 concentration in headspace: ambient CO2 (0.03% v/v ± 0.005), and two high CO2 levels (5% ± 0.4 and 10% ± 0.5 v/v CO2). Moreover, 1% (v/v) of CH4 was added to all sets prepared for the methanotrophy test since low-affinity methanotrophy in the tested soils had been reported previously. Gas concentrations (CH4, CO2, O2) in headspace were measured using gas chromatography method. We observed that the examined soils differed in their ability to produce CH4 as follows: Haplic Podzol = Eutric Cambisol > Mollic Gleysol, as well as to consume CH4: Mollic Gleysol > Haplic Podzol > Eutric Cambisol. The CH4 emissions started faster in Gleysol, but the final CH4 concentration and CH4 production rate in this soil were significantly lower than in the two other soils. The CH4 uptake rate significantly differed among the tested soils. The MANOVA confirmed the significance of the soil-type factor in determining both process rates, whereas the effect of CO2 level and the interaction between both factors were not significant. The amount of consumed O2 during CH4 oxidation was also characteristic for examined soil, but did not differ significantly between CO2 variants. CH4 production and consumption in three different soils (Eutric Cambisol, Haplic Podzol and Mollic Gleysol) collected from periodically waterlogged arable fields were more strongly affected by soil properties than by high CO2 concentration. In contrast, the high CO2 level significantly decreased CO2 production accompanying tested the CH4-related processes.

Interactive effects of nitrate and oxygen on methane oxidation in three different soils

The ability of soil to uptake methane is regulated by several factors affecting soil microbial activity. The soil oxygen concentration is usually lower than the concentration of atmospheric air, and nitrogen fertilization contributes to a significant increase in nitrate-N in soil. Therefore, we selected three agricultural soils (Eutric Cambisol, Haplic Podzol, Mollic Gleysol) to investigate interactive effects of oxygen and nitrate (KNO3) on CH4 oxidation including different gradients of O2 (20%, 10%, 5%, 2%) and nitrate (0, 100, 200 mg N kg−1). The soils varied in their response to O2 and nitrate treatments. In the absence of nitrate, all soils completely oxidized added CH4 (1%) under the oxygen concentrations used (except 2%O2); however, low oxygen (5%; 10%O2) was optimal. Both nitrate doses strongly stimulated methane oxidation at 2%O2 in Podzol and Gleysol, but generally inhibited CH4 uptake in Cambisol.

A Modeling-Based Approach for Soil Frost Detection in the Northern Boreal Forest Region With C-Band SAR

This paper presents a new approach for monitoring soil frost in the northern boreal forest region using co-polarized C-band synthetic aperture radar (SAR) data. Due to the high sensitivity of the C-band signal to vegetation, estimating the soil freeze/thaw (F/T) state directly from the measured backscatter is not feasible over dense vegetation, such as boreal forests. The presented method is based on applying a simple zeroth-order model to estimate the contribution of the ground and the forest canopy on the observed total backscatter. The retrieved ground and canopy backscatter values were compared with in situ information on soil F/T state. By using a linear least sum of square errors classification algorithm, the retrieved ground and canopy backscatter values representing frozen and thawed ground were successfully separated. The method was tested for various soil types and incidence angles. For soil types with higher water holding capacities and lower infiltration rates such as fine Haplic Podzol and Umbric Gleysol, the estimation accuracy of the F/T state was over 97%, whereas for drier, well-drained soil types such as Haplic Arenosol and Coarse Haplic Podzol it was over 94%. Estimation accuracy slightly increased with higher incidence angle. The method is not feasible in rocky terrain due to very low water content, or in wet snow conditions due to lack of penetration of the C-band SAR signal through wet snow. With low ancillary data and computational requirements, the proposed method is applicable for continuous near real-time monitoring of soil F/T state.

Biochar efficiency in copper removal from Haplic soils

The main aim of the study was to examine the biochar efficiency in copper (Cu) ion removal from Haplic (Luvisol, Podzol) soils. In other words, the most effective biochar dose and the most favorable environment pH value were proposed. The copper removal was carried out based on the adsorption process. The results of kinetics measurements were modeled using Richie equation, whereas the adsorption isotherms using Langmuir–Freundlich and Dubinin–Radushkevich equations. The copper removal is a strongly pH-dependent process which is associated with variability of chemical Cu forms and various reactivities of organic molecules. The Cu adsorption amount was higher on silty Haplic Luvisol than on sandy Haplic Podzol mainly due to higher content of organic carbon, functional groups, clay and silt fractions as well as larger surface area. Moreover, the biochar addition increased linearly the soil surface charge and contributed to higher copper adsorption in the whole range of investigated ion concentrations. The higher the biochar dose added, the more Cu ions were adsorbed.

Methanotrophs are favored under hypoxia in ammonium-fertilized soils

Methanotrophy of arable soils is affected by N fertilization, but the knowledge about the effect of oxygen level is poorly understood; soil aeration can fluctuate and zones of low oxygen are widespread in soil. We monitored CH4 oxidation in three mineral soils (Eutric Cambisol, Haplic Podzol, Mollic Gleysol) under laboratory conditions by varying the O2 level (from 20 to 2% O2), with or without NH4+ (100 mg N kg−1). In controls (without NH4+), CH4 was oxidized completely in the O2 range from oxia (20% O2) to high hypoxia (5% O2), while the process was inhibited under microoxia (2% O2). Ammonium application decreased CH4 consumption in all soils. This negative effect was stronger at 20% and 2% O2 than under hypoxia. The highest CH4 oxidation rates and the shortest initial (lag) phases in both control and NH4+-amended soils were observed under high (5% O2) and low (10% O2) hypoxia.

Recurring surface fires cause soil degradation of forest land: A simulation experiment with the EFIMOD model

AbstractRenewal of pine forests is ecologically dependent on fires, but if fires become too frequent, they can disrupt the equilibrium and sustainability of these ecosystems. Field studies of the effects of fire are challenging because of the heterogeneity of forest ecosystems and because of the heterogeneous effect of fire on recovery of vegetation. As an alternative to complex field studies, mathematical models can be used as a tool to assess the complex dynamics of natural ecosystems as they recover after fire. The aim of this study was to apply the ecosystem model EFIMOD to analyse the effect of surface fires on soil degradation and its feedback on tree productivity in Scots pine forests on different soil types in Russia: Haplic Podzols in the Leningrad region and Psamment Entisols of the fragmented steppe in the Samara region. Simulation of the cumulative effects of fire cycles over 140 years showed that one fire did not affect growing stock but decreased soil organic matter by about 10% at both sites, and that three fires reduced the growing stock by 30% on the Haplic Podzols and 9% on the Psamment Entisols and decreased soil organic matter by about 30% on both sites. Forest fires led to the loss of soil carbon (C), as well as nitrogen (N), which is a principal limiting factor in forest ecosystems of boreal and temperate ecozones. The effect of repeated fire cycles on land degradation is similar to that of soil erosion, through the loss of soil C and N.

Biological Activity of Soils in Mountain Tundra Ecosystems under Postpyrogenic Restoration

The dynamics of the content and microbiological transformation of carbon and nitrogen compounds in the surface horizons of mountain tundra soils are considered in the postpyrogenic succession. The contents of total and labile carbon and nitrogen increase in the course of postpyrogenic soil evolution. At the same time, in the surface organic horizons, the carbon reserves, as compared to the nitrogen ones, are restored faster. The aerobic transformation of carbon compounds prevails at all the stages of the succession. The tolerance of soil organic matter toward mineralization increases as the ecosystem recovers after fire. However, this parameter reaches the values characteristic of the control soils no earlier than 60 years after the fire. The microbial communities of the podburs (Folic Podzols, Haplic Podzols) restore their functional activity fast enough after the fire (about three years). In the remote future, the effect of fire leads to an increase in the availability of soil nitrogen and in the soil ability to fix atmospheric nitrogen. Despite the temporary increase in the availability of mineral nitrogen (including nitrates) at early stages of the postpyrogenic restoration of soil systems, denitrification does not play a significant role in the biogeochemical cycle of nitrogen.

Cation binding in a soil with low exchange capacity: Implication for the structural rigidity of soil organic matter

AbstractTwo previous studies suggested that part of the cation sorption sites in soil organic matter with low exchange capacity have to be considered as “lonely”, i.e., too far from each other to allow direct cross‐linking by bivalent cations. The objective of this contribution was to understand the mechanisms controlling structural rigidity and physicochemical aging of the SOM (soil organic matter) and the role of water molecule bridges (WaMB) therein. For this, we evaluated the matrix rigidity of an organic surface layer of a Haplic Podzol on a quantitative basis, by assessing WaMB transition temperature (T*) directly after treatment with bivalent cations (Mg2+, Ca2+, or Ba2+) and after eight weeks of aging. Cation loading as well as cation type influenced matrix rigidity. Ba2+ induced the most rigid matrix and Mg2+ the weakest, which is in line with their binding strength in terms of Langmuir coefficient. The matrix rigidity increased with the cross‐linking activity, which is the product of loading and Langmuir constant of the respective cation. The aging process, however, was slowed down by the initial matrix rigidity, and the rigidity of the aged matrix decreased with increasing Langmuir constant. The degree of aging increased with increasing hydration enthalpy of the cation and decreased with increasing cation loading. Thus, directly after cation treatment, direct cross‐links by multivalent cations were most relevant, but WaMB increasingly gained influence on the matrix rigidity during aging. The untreated sample revealed a considerable number of WaMB, resulting in a fairly rigid and strongly cross‐linked matrix which, however, flexibly reacts on external influences like change in cation concentration or relative humidity. With these findings, the ideas on the relevance of indirect CaB‐WaMB associations between distant sorption sites for the rigidity and flexibility of the OM matrix as proposed in previous studies were confirmed on a mechanistic basis in this study.

Methane oxidation in lead-contaminated mineral soils under different moisture levels

Methane (CH4) oxidation in soil reduces the concentration of this greenhouse gas due to the activity of methanotrophic bacteria. This process is influenced by chemical and physical parameters of soil. We tested the methanotrophic activity of selected mineral soils (Mollic Gleysol, Haplic Podzol, Eutric Cambisol) contaminated with lead (Pb) under different soil water potentials (pF 0; 2.2; 3.2). The heavy metal was added as PbCl2 in two doses. Together with the initial content of Pb in soils, the final contents of heavy metal in different soils were 11.6 and 30.8 mg kg−1 in Eutric Cambisol, 7.1 and 26.3 mg kg−1 in Haplic Podzol, and 12.2 and 31.4 mg kg−1 in Mollic Gleysol (dry mass of the soil is specified in all cases). The results showed relatively low sensitivity of methane oxidation to the addition of the heavy metal. The major factor controlling this process was soil water content, which in most cases turned out to be the most optimal at pF = 2.2.

Effect of biochar application on the physical properties of Haplic Podzol

The paper presents the results of a study on the effect of biochar application to soil on the basic physical properties of Haplic Podzol. In a six-year (2010–2015) field experiment, the physical properties of biochar-amended Haplic Podzol originating from glaciofluvial fine-grained loamy sand (LS) were studied. The experiment was carried out on three plots with an area of 5.0m2 each. Biochar produced from wheat straw in the process of pyrolysis at 650°C was applied to the soil in the following rates: treatment A – 45.0Mgha−1, treatment B – 30.0Mgha−1 and treatment C – Control (soil without the addition of biochar). Biochar was applied to the soil (April 2011) and mixed with the soil surface layer (0–10m). Soil samples, their natural structure preserved intact, were collected six times (sampling dates 0-V), once a year, during the vegetation season – after harvest (2nd decade of August). Soil samples were taken from layers: 0–10cm, 10–20cm and 20–30cm, in six replicates, using 100cm3 metal cylinders. The following physical properties of the soil were determined: particle density (PD), bulk density (BD), total porosity (TP), field air capacity at the potential of −15.5kPa (content of macropores with Φ>20μm – FAC), air permeability at the potential of −15.5kPa (FAP), water content at sampling (SM), field water capacity (at −15.5kPa) (FC), available water content (AWC), unavailable water content (UWC), and the ratio FC/TP was calculated. Analysis of the results indicated a positive effect of biochar application on most of the studied physical properties. Compared to soil without biochar addition, soil compaction was lower, there was an improvement in the soil air properties (FAC and FAP) and an increase in water available to plants (AWC). It should be emphasized, however, that the effect of biochar was short-lived, and also limited in depth as it related mainly to the layer of 0–10cm. The positive effect of biochar on the soil properties was observable mainly at sampling dates I and II. Starting from sampling date III, the differences noted in the values of the soil properties under study gradually diminished, and at sampling date V they virtually disappeared. The statistical evaluation of the results confirmed the observed impact of biochar on the soil, its range and stability. It demonstrated that the effect of biochar on the soil is positive but short-lasting, as starting with the second year after biochar application (sampling date II) its decrease was noted.

Effect of forest site types on the exchangeable and water-soluble cations distribution in the soil profiles

Abstract The aim of this research was to assess the impact of forest site types on the ionic composition of the soil sorption complex and soil water extracts in a soil profile. Three forest site types: coniferous forest (CF), coniferous-deciduous forest (CDF), and deciduousconiferous forest (DCF), were selected for the studies. Three dominant soil types were distinguished on the studied plots: Haplic Podzol, Dystric Arenosol, and Dystric Cambisol. Calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and aluminium (Al) in the soil sorption complex and soil water extracts were determined. Ca is a dominant cation in the soil sorption complex in organic horizon, while Al in mineral soil horizons. The differences between forest site types in ionic composition of soil water extracts were observed, mainly in the organic horizon and the horizons below the rooting zone. The vegetation affected the Ca/Al and base cations to Al molar (BC/Al) ratios. The Ca/Al and the BC/Al molar ratios increased in the sequence of sites: CF &lt; CDF &lt; DCF.

Relationships between exchangeable and water-soluble cations in the forest soil

Abstract The aim of this research was to assess the relationships between exchangeable and water-soluble cations in forest soil types. Three dominant soil types were distinguished on studied plots: Haplic Podzol, Dystric Arenosol and Dystric Cambisol. Ca, Mg, K, Na and Al in soil sorption complex and soil water extracts were determined. The differentiation of the ionic composition of soil sorption complex and soil water extracts within a soil type and amongst soil types was presented. The sum of cations in the soil and water extracts was the highest in Dystric Cambisol and the lowest in Haplic Podzol. Ca is a dominant cation in soil and soil water extracts in organic horizon, whilst Al is dominant in mineral soil horizons. The Ca/Al and the base cations to Al (BC/Al) molar ratios increased in the sequence of soils: Haplic Podzol &lt; Dystric Arenosol &lt; Dystric Cambisol. The parent material, soil-forming processes and vegetation cover affected the Ca/Al and BC/Al ratios.

Strong gradients in nitrogen and carbon stocks at temperate forest edges

Due to forest fragmentation, forest edges have become dominant features in landscapes around the world. Forest edges are exposed to a different microclimate in terms of air and soil temperature, light availability, soil moisture and wind speed than the forest interior. Furthermore, forest edges catch more atmospheric deposition, due to obstruction of the wind profile causing advection and turbulent exchange. Coniferous forest types are subjected to higher N deposition due to their higher Leaf Area Index (LAI), evergreen character and higher collecting efficiency of needles compared to leaves. In Europe, highest deposition values coincide with intensive livestock breeding areas, such as northern Belgium. It is still unclear how this elevated atmospheric deposition affects N and carbon (C) stocks at temperate forest edges. We assessed the N and C stocks of the aboveground (leaves/needles, wood) and belowground (forest floor, coarse and fine roots, mineral soil) forest pools along edge-to-interior transects in six forests, located in Belgium (two oak and two pine forests) and in Denmark (two spruce forests) on sandy haplic podzols. The total stocks increased towards the forest edge by 30% for N and 43% for C, averaged over all forests, within a confidence interval of 95% (which was in some cases rather wide). The aboveground wood stocks increased by 56% for N and C, the root stocks by 48% for N and C and the mineral soil stocks increased by circa 30% for N and C. Soil C sequestration (calculated via a static N balance based on N throughfall and leaching) increased at the forest edges, being on average 646 and 289kgha−1year−1 in the forest edge and interior, respectively. Forest type effects were less prominent than edge effects, with no amplified edge effect on N and C stocks in the coniferous forest types. Nevertheless, our results show the importance of incorporating forest edges when monitoring C storage on a landscape scale. The question arises, however, how much longer such forest edges will continue to accrue additional C when subjected to continuously high atmospheric N deposition.

CONTENT OF SULPHATE SULPHUR IN DIFFERENT TYPES OF SOILS IN THE PODKARPACKIE REGION

The aim of the investigation was the estimation of sulphate sulphur in soils in the Podkarpackie Province. The content of sulphate sulphur within the soils developed on flysch works subject to strong spatial variability of 0.87 g kg-1 in the Przemyoel Foothills to 2.00 g kg-1 in the Ciezkowickie and Strzyzowskie Foothills. The content of sulphate sulphur in soils is positively correlated with the content of humus in the Western Bieszczady Mountains and the content of colloidal clay fraction within the Tarnogrodzki Plateau and Rzeszow Foothills. In soil types: Haplic Cambisol, Haplic Cambisol (Dystric), Haplic Cambisol Podzolised, Haplic Podzol and Haplic Luvisol found in the Podkarpackie Province there is no significant variation of the sulphate Sulphur content (average 1.73-1.93mg100g-1), but less sulphur was found in Haplic Cambisol (Eutric) soils.

Calculating Organic Carbon Stock from Forest Soils

The organic carbon stock (SOC) (t/ha) was calculated in different approaches in order to enhance the differences among methods and their utility regarding specific studies. Using data obtained in Romania (2000-2012) from 4,500 profiles and 9,523 soil horizons, the organic carbon stock was calculated for the main forest soils (18 types) using three different methods: 1) on pedogenetical horizons, by soil bulk density and depth class/horizon thickness; 2) by soil type and standard depths; 3) using regression equations between the quantity of organic C and harvesting depths. Even though the same data were used, the differences between the values of C stock obtained from the three methods were relatively high. The first method led to an overvaluation of the C stock. The differences between methods 1 and 2 were high (and reached 33% for andosol), while the differences between methods 2 and 3 were smaller (a maximum of 23% for rendzic leptosol). The differences between methods 2 and 3 were significantly lower especially for andosol, arenosol and vertisol. A thorough analysis of all three methods concluded that the best method to evaluate the organic C stock was to distribute the obtained values on the following standard depths: 0 - 10 cm; 10 - 20 cm; 20 - 40 cm; &gt; 40 cm. For each soil type, a correlation between the quantity of organic C and the sample harvesting depth was also established. These correlations were significant for all types of soil; however, lower correlation coefficients were registered for rendzic leptosol, haplic podzol and fluvisol.