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Due to the spatial heterogeneity, root presence and other specific properties, measurement of forest soil hydraulic properties is difficult. Forests are generally hydrologically important systems that can mitigate negative climate change impact, and specifically, forest soil represents crucial water reservoir. A common forest management strategy is to plant monocultural stands of trees. Due to the differences in trees characteristics, e.g., root system, litter and leaf area, the development of soil undergoes specific changes according to the planted species. The main aim of this study is to investigate the connection between the tree species and hydro-physical properties of forest soil with focus on long term soil moisture and temperature regime monitoring. This research brings an early-stage view to data obtained from May 2021 up to nowadays.A set of 55 TDT (time domain transmission) soil moisture and temperature sensors were installed into three nearby locations. In each of those a monoculture stand of beech (Fagus sylvatica), spruce (Picea Abies), and larch (Larix Decidua) are planted. Half of the sensors are used for measuring the mineral soil moisture in depth of -15 to -29 cm below soil surface and point temperature of -23, -15, +5 cm relative to the surface, the rest is used for measuring the topsoil moisture from the surface to the depth of -14 cm and point temperatures in levels of -8, 0 and +15 cm.Results shows distinct differences in soil moisture among tested tree species. After longer period without precipitation (period of soil-water loss), the highest differences in volumetric water content (VWC) were observed. After one-month period without rain in early summer, mean values of VWC for topsoil were 35% for beach, 28% for larch, and 21% for spruce. Overall, the beech stands showed the highest ability to maintain soil water after periods of soil water loss and therefore, potentially exhibited the strongest resistance towards soil drought. By contrast, spruce tends to lose water relatively fast which can be problematic especially in events of long-term drought. For the surface temperature during vegetation season, the highest values were observed in larch stands followed by spruce and the lowest in beach. These findings probably corresponding to different solar radiation permeability of tree canopies. The observed effects of tree species on soil moisture and temperature should be considered for hydrological modelling, future forest planning, and water management improvement of forest soil.

The distribution of rainwater and subsurface runoff formation in forest soil can be strongly affected by soil disturbance and microrelief. This study analyses preferential pathways of dyed water after artificial rainfall on a forested slope with pits and mounds formed by historical tree uprooting.Two heavy rain experiments were carried out using a special tailored rainfall simulator. The first plot was situated above the pit-mound transition. The second (control) plot was situated at a nearby undisturbed surface. The soil profiles were excavated after the rainfall simulation and the dyed stained patches indicating preferential flow were photographed. Subsequently, advanced image analysis was performed to assess differences in water flow patterns in both soil profiles.The results show contrasting dyed patterns in soil, indicating significant differences in the preferential flow and runoff formation at each plot. The dye-stained patches revealed in image analysis indicated much higher water entry into subsoil of pit profile (31 % of area) than in control plot (8 %). These findings support our previous hypothesis about the significant impacts of terrain depressions formed by tree uprooting on preferential flow and subsurface runoff formation. These terrain disturbances may redirect shallow subsurface flow and force the redistribution of water into deep subsoil layers. The effects of pit-mound microrelief on the hydrology of forested slopes should be considered in future hydrological modelling and land management.

The soil hydraulic properties of two low-organic soils (Fluvisol; Regosol) were investigated following their amendment with biochar alone or in combination with manure, compost and co-composted biochar. Self-irrigating boxes containing the soil and amendment combinations were purposed with a battery of soil moisture sensors as well as soil porewater sampling devices. Static sampling determined bulk density, porosity and derived soil water retention curves. The aim of this study was to identify the most advantageous amendment combinations to enhance soil water retention whilst simultaneously avoiding excessive nutrient leaching arising, primarily, from manure application. Biochar significantly decreased bulk density and increased total porosity when compared to compost in the Fluvisol, whereas manure affected the greatest changes in the Regosol. All of the tested amendments adjusted the shape or extent of the soil water retention curves, but biochar addition resulted in the greatest increase (⁓50%) in easily available water content (for plants) in both soils, when compared to the control. Saturated hydraulic conductivity was, however, not changed by any of the amendments which reflects a lack of influence on infiltration. An enhancement in nutrient retention occurred in some of the soil amendment configurations, such as for co-composted biochar at 2% dosage and 5% manure-biochar mixture, as revealed by porewater analysis. In summary, the application of biochar with and without additional compost and manure can enhance soil water retention in low-organic soils whilst maintaining or enhancing nutrient retention. Such finding supports the application of mixed organic amendments to low-organic (and therefore drought-prone) arable soils.

The application of biochar on two contrasting soils was tested in order to assess its effects on soil hydraulic properties (SHP) and study the interaction between water and the biochar surface (e.g., the swelling effect). Two contrasting soil types were enriched with 0, 2 and 5% (wt.) doses of grape stalks biochar in order to prepare soil samples for a 14-days continually saturated laboratory experiment. H2O bonds to the biochar surface were detected using FTIR spectroscopy. Results show that water molecules were bound through polar hydrogen bonds to O H and C O H, and these interactions caused (i) intensive swelling, which decreased the bulk density and enhanced the water holding capacity (up to 5% in the case of sandy loam and 5% biochar dose), and (ii) significantly decreased Ks in both soils (with a maximum difference of 82.6%). The results of this laboratory experiment provide useful information about the significant effect of presented biochar in two contrasting soils, and its application appears to be an potential option for addressing drought (especially in coarser soils). Nevertheless, these findings must be verified under field conditions where the presence of biota and long-term effects can be taken into account.

The layering of the soil profile can influence the accumulation of infiltrated water and the way in which subsurface runoff is formed. This paper examines a mountain podzol characterized by clearly developed soil horizons. After these horizons had been identified, distinct soil layers were defined (the eluvial horizon, the spodic horizon (undifferentiated), and weathered bedrock). Saturated hydraulic conductivity (Ks), particle size distribution and bulk density were measured in these layers. A visualization of the distribution of infiltrated water in the podzolic profile was performed using a dye tracer experiment. The accumulation of dyed water and a distinct lateral flow were detected in the eluvial layer. Only limited entry of water into the spodic layer was observed. These effects were caused by changes in soil hydraulic properties (SHP) among the investigated layers. For the spodic horizons, the measured Ks value (crucial SHP) was significantly lower than the Ks values for the other tested horizons. The probable reason for the lower Ks was an accumulation of fine particles and various substances in the spodic horizons, and corresponding changes in the porous system. The observed effects of layering indicate that water can be accumulated and subsurface runoff can be formed over the spodic layer during intensive rain or snow melting.

Soil recovery is crucial for successful ecosystem restoration at post-mining sites. Water infiltration and preferential flow in soil are important but little studied soil characteristics. In this study, we explore effects of tree species on infiltration, geometry of preferential flows, size distribution and origin of pores, and related properties of soil. An experiment was conducted at post-mining sites developing under monocultures of three tree species (alder, oak and spruce) after lignite mining near Sokolov, Czech Republic. A key hydraulic parameter of soil, field saturated hydraulic conductivity (Ks), measured in topsoil, was highest under alder (mean value of 6.9 × 10−5 ms−1) and lowest under spruce (mean value of 1.9 × 10−5 ms−1). In subsoil, there were no significant differences in Ks between tree species. For the alder site, dye tracer tests showed that water penetrates almost uniformly to the top 15 cm of soil depth and with the greatest lateral flow. In a deeper part of the alder soil profile, preferential flow was concentrated around earthworm burrows and roots, where the two often occur together. Thin soil sections of alder soil show that earthworm casts and burrows substantially contribute to porosity around the roots (59 % of dyed worm-created structures in alder-root microsite). A similar situation was observed in oak, but preferential flows along roots started from the surface and cross section of preferential flow was smaller than in alder soil. In spruce, preferential flow was concentrated around roots and cracks in claystones and the cross section was even smaller. Comparison among the forest stands indicates that overall porosity does not correspond with infiltration of dye tracer and Ks, which seem to be more driven by pore size distribution and pore connectivity. This is consistent with larger occurrence of macropores (>300 μm) in alder. The results show that trees affect infiltration and preferential flow in soil by their specific root systems and to a large extent indirectly by effect of litter quality on earthworm populations, which then enhance macroporosity and pore connectivity.

In order to obtain infiltration parameters and analytical expressions of the cumulative infiltration and infiltration rate, raw infiltration data are often evaluated using various infiltration equations. Knowledge about the evaluation variability of these equations in the specific case of extremely heterogeneous soils provides important information for many hydrological and engineering applications. This paper evaluates five well-established physically-based equations (Eqs.) - Brutsaert (1977), Green and Ampt (1911), Kutilek and Krejca (1987), Philip (1957), Swartzendruber (1987) -, and two empirical Eqs. - Horton (1940), Mezencev (1948) using measured infiltration data. This paper also compares sorptivity (S) and saturated hydraulic conductivity (Ks) estimates of these Eqs. with the reference estimates using early-time parts resp. quasi-steady parts of raw data. A total of 47 single ring infiltration experiments (datasets measured on three different sites of hydrologically important mountain podzols) were evaluated using the seven Eqs. and also using the methods for reference estimates of S and Ks. From the quality-of-fit perspective, all of the seven Eqs. characterized large part of the datasets properly. In some cases, Philip, Kutilek and Krejca, and Green and Ampt Eqs. led to poor fits of the datasets (measured mostly on site 3 characterized by the lowest thicknesses of the organic horizon, and a more bleached eluvial horizon than on the other tested sites). For the parameters evaluated on site 3, 1) the mean S estimates of Green and Ampt, Kutilek and Krejca, and Philip were significantly lower than the mean S estimates of Brutsaert and Swartzendruber, and 2) the mean Ks estimates of Kutilek and Krejca, and of Philip, were significantly lower than the mean Ks estimates of Brutsaert, Swartzendruber and Horton. The Swartzendruber and Brutsaert Eqs. exhibited 1) high quality of fitting and 2) good consistency of the Ks estimates with reference values.

Vegetation cover is found to be an ideal solution to most problems of erosion on steep slopes. Biodegradable geotextiles (GTXs) have been proved to provide sufficient protection against soil loss in the period before vegetation reaches maturity, so favouring soil formation processes. In this study, 500 g m−2 jute (J500), 400 g m−2 (C400), and 700 g m−2 coir (C700) GTXs were first installed on a 9° slope under “no-infiltration” laboratory conditions, then on a 27° slope under natural field conditions. The impact of GTXs on run-off and soil loss was investigated to compare the performance of GTXs under different conditions. Laboratory run-off ratio (percentage portion of control plot) equalled 78, 83, and 91 %, while peak discharge ratio equalled 83, 91, and 97 % for J500, C700, and C400 respectively. In the field, a run-off ratio of 31, 62, and 79 %, and peak discharge ratio of 37, 74, and 87 % were recorded for C700, J500, and C400 respectively. All tested GTXs significantly decreased soil erosion. The greatest soil loss reduction in the field was observed for J500 (by 99.4 %), followed by C700 (by 97.9 %) and C400 (by 93.8 %). Irrespective of slope gradient or experimental condition, C400 performed with lower run-off and peak discharge reduction than J500 and C700. The performance ranking of J500 and C700 in the laboratory differed from the field, which may be explained by different slope gradients, and also by the role of soil, which was not included in the laboratory experiment.

A woody-biochar was added to waste biomass during a composting process. The resulting compost-char was amended to a metal contaminated soil and two plant species, L. perenne and E. sativa, were grown in a pot experiment to determine 1) plant survival and stress factors, 2) uptake of metals to plants and, 3) chemical characteristics of sampled soils and pore waters. Compost supplemented with biochar after the composting process were also tested, as well as a commercially available compost, for comparison. Co-composting with biochar hastened the composting process, resulting in a composite material of reduced odour, increased maturity, circum-neutral pH and increased moisture retention than compost (increase by 3% of easily removable water content). When amended to the soil, CaCl2 extractable and pore water metals s were reduced by all compost treatments with little influence of biochar addition at any tested dose. Plant growth success was promoted furthest by the addition of co-composted biochar to the test soil, especially in the case of E. sativa. For both tested plant species significant reductions in plant metal concentrations (e.g. 8-times for Zn) were achieved, against the control soil, by compost, regardless of biochar addition. The results of this study demonstrate that the addition of biochar into the composting process can hasten the stability of the resulting compost-char, with more favourable characteristics as a soil amendment/improver than compost alone. This appears achievable whilst also maintaining the provision of available nutrients to soils and the reduction of metal mobility, and improved conditions for plant establishment.

The impact of erosion control geotextiles on the surface runoff from slopes is quite variable and depends strongly on site-specific conditions (soil characteristics, slope morphology, climate, etc.), as has been shown in several earlier studies. In addition, little is known about the proportion of runoff reduction that is caused by the geotextile and the proportion that is caused by soil characteristics. To shed more light on this issue, an experiment was carried out to test the impact of 500 g m−2 jute nets (J500) and 400 g m−2; 700 g m−2 coir nets (C400, C700) on the surface runoff from simulated rainfall of four different intensities (I 1 = 18.7; I 2 = 27.2; I 3 = 53.6; I 4 = 90.5 mm h−1). Data on runoff volume, peak discharge and time to peak discharge were collected from 40 simulated rainfall events. An impermeable “no-soil” subgrade was used to examine the impact of the geotextile on runoff without any influence of soil. All tested geotextiles significantly reduced runoff (volume, peak discharge) at all rainfall intensities, with the exception of C400 and C700 during simulated rainfall intensity I 4. J500 seemed to have the most effective runoff reduction performance at all rainfall intensities. In general, as the rainfall intensity increased, the effectiveness of the geotextiles decreased. Interesting behaviour was observed for J500 under simulated rainfall intensity I 4—the effectiveness of the geotextile increased with the duration of the rainfall.

Saturated hydraulic conductivity (Ks) is a key input parameter for modeling water flow in soils. Well-established methods exist, but there is no methodological standard or benchmark. This paper presents a comparison of three well-established measurement methods, which we used in the specific conditions of extremely heterogeneous mountain podzols. The following devices were applied to undisturbed soil core samples (diameter of 5.6 cm). Ks was estimated for a shallow subsurface ash-gray layer. The geometric mean values for Ks measured using these three methods were: GP — 4.41 × 10 − 6 ms − 1 , SR — 3.20 × 10 − 6 ms − 1 , and LP — 7.09 × 10 − 6 ms − 1 . The mean values obtained using field methods were not statistically different. The laboratory permeameter yielded slightly higher values than the field methods. From the engineering perspective, all tested methods provided similar mean values.

The aim of this study was to document the spatial and temporal variability of soil hydraulic properties (SHP) present in an uncultivated soil formed by fluvial sediments (Fluvisol in our case). Specifically, a small scale experimental plot (10 × 10 m) was used during four field works evenly distributed in one vegetation season (8 months) in order to demonstrate the importance (representativeness) of sufficient sampling in time and space. During each field work, six soil water retention curves (SWRC) for two depths (25 and 60 cm; reflecting the position of installed tensiometers and the presence of two layers of the soil profile) and ten saturated hydraulic conductivities (Ksat) were determined. The measured values of SHP were used for the HYDRUS-1D model in order to observe the influence of the spatial and temporal variability on the modelled soil water regime. The vegetation season was for modelling purposes split into four two-month sub-periods (reflecting air temperature and precipitation conditions of the season), each represented by specific soil hydraulic properties. The results indicated that the spatial variability of SWRC completely covered for any possible temporal variability as the coefficients of variation (Cv) of the SWRC parameters were up to 127% (in the case of residual soil water content – ϴr) and from 62% to 88% concerning the alpha shape parameter (α). The remaining two SWRC parameters (θs and n) were less variable. The spatial variability of Ksat expressed by Cv equalled 128%. The modelling results showed a significant improvement of the soil water regime prediction when the proper SWRC was utilized (compared to its areal average). The improvement was reflected by the overall increase of the Nash-Sutcliffe efficiency (from 0.20 to 0.68) and a decrease in root mean square error (RMSE) (by 38%) for the measurement at 25 cm. The improvement of the model prediction was less significant at the depth of 60 cm. In summary, the high spatial variability of soil hydraulic properties in the uncultivated Fluvisol (representing permeable sandy fluvial sediments) proved to be superior to their temporal changes and it is therefore worth quantifying its extent for modelling purposes. The described variability of SHP will serve as a benchmark for the further investigation of the organic matter influence on the soil water regime in field conditions.