Biocrust effects on soil infiltrability in the Mu Us Desert: Soil hydraulic properties analysis and modeling

Abstract The presence of biocrusts changes water infiltration in the Mu Us Desert. Knowledge of the hydraulic properties of biocrusts and parameterization of soil hydraulic properties are important to improve simulation of infiltration and soil water dynamics in vegetation-soil-water models. In this study, four treatments, including bare land with sporadic cyanobacterial biocrusts (BL), lichen-dominated biocrusts (LB), early-successional moss biocrusts (EMB), and late-successional moss biocrusts (LMB), were established to evaluate the effects of biocrust development on soil water infiltration in the Mu Us Desert, northwest of China. Moreover, a combined Wooding inverse approach was used for the estimation of soil hydraulic parameters. The results showed that infiltration rate followed the pattern BL > LB > EMB > LMB. Moreover, the LB, EMB, and LMB treatments had significantly lower infiltration rates than the BL treatment. The saturated soil moisture (θs ) and shape parameter (α VG) for the EMB and LMB treatments were higher than that for the BL and LB treatments, although the difference among four treatments was insignificant. Water retention increased with biocrust development at high-pressure heads, whereas the opposite was observed at low-pressure heads. The development of biocrusts influences van Genuchten parameters, subsequently affects the water retention curve, and thereby alters available water in the biocrust layer. The findings regarding the parameterization of soil hydraulic properties have important implications for the simulation of eco-hydrological processes in dryland ecosystems.

Download Full-text

The influence of microplastic on soil hydraulic properties

10.5194/egusphere-egu2020-9337 ◽

2020 ◽

Author(s):

Patrizia Hangele ◽

Katharina Luise Müller ◽

Hannes Laermanns ◽

Christina Bogner

Keyword(s):

Hydraulic Conductivity ◽

Soil Water ◽

Hydraulic Properties ◽

Water Retention ◽

Pore Space ◽

Water Retention Curve ◽

Soil Hydraulic Properties ◽

Soil Water Retention ◽

Soil Hydraulic Conductivity ◽

Soil Hydraulic

The need to study the occurrence and effects of microplastic (MP) in different ecosystems has become apparent by a variety of studies in the past years. Until recently, research regarding MP in the environment has mainly focused on marine systems. Within terrestrial systems, studies suggest soils to be the biggest sink for MP. Some studies now started to explore the presence of MP in soils. However, there is a substantial lack of the basic mechanistic understanding of the behaviour of MP particles within soils.This study investigates how the presence of MP in soils affects their hydraulic properties. In order to understand these processes, experiments are set up under controlled laboratory conditions as to set unknown influencing variables to a minimum. Different substrates, from simple sands to undisturbed soils, are investigated in soil cylinders. MP particles of different sizes and forms of the most common plastic types are applied to the surface of the soil cylinders and undergo an irrigation for the MP particles to infiltrate. Soil-water retention curves and soil hydraulic conductivity are measured before and after the application of MP particles. It is hypothesised that the infiltrated MP particles clog a part of the pore space and should thus reduce soil hydraulic conductivity and change the soil-water retention curve of the sample. Knowledge about the influence of MP on soil hydraulic properties are crucial to understand transport and retention of MP in soils.

Download Full-text

Direct measurement of the soil water retention curve using X-ray absorption

Hydrology and Earth System Sciences ◽

10.5194/hess-8-2-2004 ◽

2004 ◽

Vol 8 (1) ◽

pp. 2-7 ◽

Cited By ~ 19

Author(s):

A. Bayer ◽

H.-J. Vogel ◽

K. Roth

Keyword(s):

Soil Water ◽

Hydraulic Properties ◽

Capillary Rise ◽

Water Dynamics ◽

Richards Equation ◽

Water Retention Curve ◽

Soil Hydraulic Properties ◽

X Ray ◽

Soil Hydraulic ◽

X Ray Absorption

Abstract. X-ray absorption measurements have been explored as a fast experimental approach to determine soil hydraulic properties and to study rapid dynamic processes. As examples, the pressure-saturation relation θ(Ψ) for a uniform sand column has been considered as has capillary rise in an initially dry sintered glass column. The θ(Ψ)-relation is in reasonable agreement with that obtained by inverting a traditional multi-step outflow experiment. Monitoring the initial phase of capillary rise reveals behaviour that deviates qualitatively from the single-phase, local-equilibrium regime described by Richards’ equation. Keywords: X-ray absorption, soil hydraulic properties, soil water dynamics, Richards’ equation

Download Full-text

Inverse estimation of soil hydraulic properties and water repellency following artificially induced drought stress

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2018-0002 ◽

2018 ◽

Vol 66 (2) ◽

pp. 170-180 ◽

Cited By ~ 7

Author(s):

Vilim Filipović ◽

Thomas Weninger ◽

Lana Filipović ◽

Andreas Schwen ◽

Keith L. Bristow ◽

...

Keyword(s):

Soil Water ◽

Inverse Modeling ◽

Hydraulic Properties ◽

Global Climate ◽

Water Repellency ◽

Irrigation Event ◽

Water Infiltration ◽

Soil Hydraulic Properties ◽

Soil Water Repellency ◽

Soil Hydraulic

AbstractGlobal climate change is projected to continue and result in prolonged and more intense droughts, which can increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, withR2and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (Ks) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.

Download Full-text

Assessing the cover crop effect on soil hydraulic properties by inverse modelling in a 10-year field trial

10.5194/hess-2018-372 ◽

2018 ◽

Author(s):

José Luis Gabriel ◽

Miguel Quemada ◽

Diana Martín-Lammerding ◽

Marnik Vanclooster

Keyword(s):

Soil Water ◽

Cover Crop ◽

Hydraulic Properties ◽

Water Retention ◽

Soil Hydraulic Properties ◽

Cover Cropping ◽

Term Change ◽

Soil Hydraulic ◽

The Impact

Abstract. Cover cropping in agriculture is expected to enhance many agricultural and ecosystems functions and services. Yet, few studies are available allowing to evaluate the impact of cover cropping on the long term change of soil hydrologic functions. We assessed the long term change of the soil hydraulic properties due to cover cropping by means of a 10-year field experiment. We monitored continuously soil water content in non cover cropped and cover cropped fields by means of capacitance probes. We subsequently determined the hydraulic properties by inverting the soil hydrological model WAVE, using the time series of the 10 year monitoring data in the object function. We observed two main impacts, each having their own time dynamics. First, we observed an initial compaction as a result of the minimum tillage. This initial negative effect was followed by a more positive cover crop effect. The positive cover crop effect consisted in an increase of the soil micro- and macro-porosity, improving the structure. This resulted in a larger soil water retention capacity. This latter improvement was mainly observed below 20 cm, and mostly in the soil layer between 40 and 80 cm depth. This study shows that the expected cover crop competition for water with the main crop can be compensated by an improvement of the water retention in the intermediate layers of the soil profile. This may enhance the hydrologic functions of agricultural soils in arid and semiarid regions which often are constrained by water stress.

Download Full-text

Measurement of soil hydraulic properties of structured and repacked soils

10.5194/egusphere-egu21-3985 ◽

2021 ◽

Author(s):

Urša Pečan ◽

Luka Žvokelj ◽

Jure Ferlin ◽

Vesna Zupanc ◽

Marina Pintar

Keyword(s):

Soil Water ◽

Hydraulic Properties ◽

Water Retention ◽

Soil Samples ◽

Measuring System ◽

Soil Hydraulic Properties ◽

Soil Water Retention ◽

Undisturbed Soil ◽

Soil Hydraulic ◽

Low Tension

Soil hydraulic properties provide important information about soil behavior under unsaturated and saturated conditions. Often sampling of undisturbed soils is not possible and soil samples have to be repacked for laboratory analysis. The HYPROP&#174; measuring system (METERgroup, Munich, Germany) is a convenient method for determination of soil water retention characteristics and unsaturated hydraulic conductivity of undisturbed soil samples. It measures the matric potential of the saturated and drying soil sample using two tensiometers placed at different depths. Although the tensiometers are based on a new design that theoretically withstands cavitation at higher tension values, they are still considered to operate in the low tension range. Since soil water retention properties in the low tension range are strongly influenced by soil structure and pore size distribution, we were interested in the changes in hydraulic properties when measured on disturbed and then repacked samples, and undisturbed soil samples. Therefore, we investigated the soil hydraulic properties of three different soil types using the evaporation method on undisturbed and repacked samples. The results provide important insights for the interpretation of the results when the collection of undisturbed samples is not possible, and for designing laboratory experiments with repacked soils.

Download Full-text

Further tests of the HYPROP evaporation method for estimating the unsaturated soil hydraulic properties

Journal of Hydrology and Hydromechanics ◽

10.1515/johh-2017-0046 ◽

2018 ◽

Vol 66 (2) ◽

pp. 161-169 ◽

Cited By ~ 14

Author(s):

Camila R. Bezerra-Coelho ◽

Luwen Zhuang ◽

Maria C. Barbosa ◽

Miguel Alfaro Soto ◽

Martinus Th. van Genuchten

Keyword(s):

Hydraulic Conductivity ◽

Unsaturated Soil ◽

Hydraulic Properties ◽

Water Retention ◽

Measurement Techniques ◽

Richards Equation ◽

Water Retention Curve ◽

Soil Hydraulic Properties ◽

Evaporation Method ◽

Soil Hydraulic

AbstractMany soil, hydrologic and environmental applications require information about the unsaturated soil hydraulic properties. The evaporation method has long been used for estimating the drying branches of the soil hydraulic functions. An increasingly popular version of the evaporation method is the semi-automated HYPROP©measurement system (HMS) commercialized by Decagon Devices (Pullman, WA) and UMS AG (München, Germany). Several studies were previously carried out to test the HMS methodology by using the Richards equation and the van-Genuchten-Mualem (VG) or Kosugi-Mualem soil hydraulic functions to obtain synthetic data for use in the HMS analysis, and then to compare results against the original hydraulic properties. Using HYDRUS-1D, we carried out independent tests of the HYPROP system as applied to the VG functions for a broad range of soil textures. Our results closely agreed with previous findings. Accurate estimates were especially obtained for the soil water retention curve and its parameters, at least over the range of available retention measurements. We also successfully tested a dual-porosity soil, as well as an extremely coarse medium with a very high van Genuchtennvalue. The latter case gave excellent results for water retention, but failed for the hydraulic conductivity. In many cases, especially for soils with intermediate and highnvalues, an independent estimate of the saturated hydraulic conductivity should be obtained. Overall, the HMS methodology performed extremely well and as such constitutes a much-needed addition to current soil hydraulic measurement techniques.

Download Full-text

Testing an infiltrometer methodology to investigate water impact effects on both soil sealing and hydraulic properties of a loam soil under conventional tillage and no-tillage

10.5194/egusphere-egu2020-22632 ◽

2020 ◽

Author(s):

Mirko Castellini ◽

Simone Di Prima ◽

Anna Maria Stellacci ◽

Massimo Iovino ◽

Vincenzo Bagarello

Keyword(s):

Hydraulic Conductivity ◽

Hydraulic Properties ◽

Water Retention ◽

Soil Management ◽

Water Retention Curve ◽

Soil Hydraulic Properties ◽

Retention Curve ◽

Soil Sealing ◽

Loam Soil ◽

Soil Hydraulic

Testing new experimental procedures to assess the effects of the drops impact on the soil sealing formation is a main topic in soil hydrology.In this field investigation, the methodological approach proposed first by Bagarello et al. (2014) was extended to account for a greater soil infiltration surface (i.e., about 3.5 times higher), a higher range and number of heights of water pouring and to evaluate the different impact on soil management. For this purpose, the effects of three water pouring heights (low, L=3 cm; medium, M=100 cm; high, H=200 cm) on both no-tilled (NT) and conventionally tilled (CT) loam soil were investigated by Beerkan infiltration runs and using the BEST-procedure of data analysis to estimate the soil hydraulic properties.Final infiltration rate decreased when perturbing runs (i.e., M and H) were carried out as compared with the non-perturbing (L) ones (by a factor of 1.5-3.1 under NT and 3.4-4.4 under CT). Similarly, the water retention scale parameter, hg, increased (i.e., higher in absolute terms) by a factor 1.6-1.8 under NT and by a factor 1.7 under CT. Saturated hydraulic conductivity, Ks, changed significantly as a function of the increase of water pouring height; regardless of the soil management, perturbing runs caused a reduction in soil permeability by a factor 5 or 6. Effects on hydraulic functions (i.e., soil water retention curve and hydraulic conductivity function), obtained with the BEST-Steady algorithm, were also highlighted. For instance, differences in water retention curve at fixed soil pressure head values (i.e., field capacity, FC, and permanent wilting point, PWP) due to perturbing and non-perturbing runs, were estimated as higher under NT (3.8%) than CT (3.4%) for FC, and equal to 2.1% or 1.6% for PWP.Main results of this investigation confirm that a recently tilled loamy soil, without vegetation cover, can be less resilient as compared to a no-tilled one, and that tested water pouring heights methodology looks promising to mimic effects of high energy rainfall events and to quantify the soil sealing effects under alternative management of the soil.AcknowledgmentsThe work was supported by the project &#8220;STRATEGA, Sperimentazione e TRAsferimento di TEcniche innovative di aGricoltura conservativA&#8221;, funded by Regione Puglia&#8211;Dipartimento Agricoltura, Sviluppo Rurale ed Ambientale, CUP: B36J14001230007.&#160;ReferencesBagarello, V., Castellini, M., Di Prima, S., Iovino, M. 2014. Soil hydraulic properties determined by infiltration experiments and different heights of water pouring. Geoderma, 213, 492&#8211;501. https://doi.org/10.1016/j.geoderma.2013.08.032

Download Full-text

Artificial Neural Networks for Predicting the Water Retention Curve of Sicilian Agricultural Soils

Water ◽

10.3390/w10101431 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1431 ◽

Cited By ~ 10

Author(s):

Alessandro D’Emilio ◽

Rosa Aiello ◽

Simona Consoli ◽

Daniela Vanella ◽

Massimo Iovino

Keyword(s):

Neural Networks ◽

Artificial Neural Networks ◽

Soil Water ◽

Hydraulic Properties ◽

Water Retention ◽

Water Retention Curve ◽

Retention Data ◽

Soil Hydraulic Properties ◽

Retention Curve ◽

Artificial Neural

Modeling soil-water regime and solute transport in the vadose zone is strategic for estimating agricultural productivity and optimizing irrigation water management. Direct measurements of soil hydraulic properties, i.e., the water retention curve and the hydraulic conductivity function, are often expensive and time-consuming, and represent a major obstacle to the application of simulation models. As a result, there is a great interest in developing pedotransfer functions (PTFs) that predict the soil hydraulic properties from more easily measured and/or routinely surveyed soil data, such as particle size distribution, bulk density (ρb), and soil organic carbon content (OC). In this study, application of PTFs was carried out for 359 Sicilian soils by implementing five different artificial neural networks (ANNs) to estimate the parameter of the van Genuchten (vG) model for water retention curves. The raw data used to train the ANNs were soil texture, ρb, OC, and porosity. The ANNs were evaluated in their ability to predict both the vG parameters, on the basis of the normalized root-mean-square errors (NRMSE) and normalized mean absolute errors (NMAE), and the water retention data. The Akaike’s information criterion (AIC) test was also used to assess the most efficient network. Results confirmed the high predictive performance of ANNs with four input parameters (clay, sand, and silt fractions, and OC) in simulating soil water retention data, with a prediction accuracy characterized by MAE = 0.026 and RMSE = 0.069. The AIC efficiency criterion indicated that the most efficient ANN model was trained with a relatively low number of input nodes.

Download Full-text

The role of biochar particle size and hydrophobicity in improving soil hydraulic properties

10.5194/egusphere-egu21-4117 ◽

2021 ◽

Author(s):

Ifeoma Edeh ◽

Ondřej Mašek

Keyword(s):

Particle Size ◽

Hydraulic Conductivity ◽

Soil Water ◽

Hydraulic Properties ◽

Water Retention ◽

Sandy Loam ◽

Particle Sizes ◽

Soil Hydraulic Properties ◽

Soil Water Retention ◽

Soil Hydraulic

The physical properties of biochar have been shown to dramatically influence its performance as a soil amendment. Biochar particle size is one of key parameters, as it controls its specific surface area, shape, and pore distribution. Therefore, this study assessed the role of biochar particle size and hydrophobicity in controlling soil water movement and retention. Softwood pellet biochar in five particle size ranges (>2 mm, 2 &#8211; 0.5 mm, 0.5 &#8211; 0.25 mm, 0.25 &#8211; 0.063mm and <0.063 mm) was used for the experiment. These particle sizes were tested on 2 soil types (sandy loam and loamy sand) at four different application rates (1, 2, 4 and 8%).&#160; Our results showed that biochar hydrophobicity increased with decreasing biochar particle size, leading to a reduction in its water retention capacity. The effect of biochar on soil hydraulic properties varied with different rate of application and particle sizes. With increasing rate of application, water retention increased while hydraulic conductivity decreased. Water content at field capacity, permanent wilting point, and the available water content increased with increasing biochar particle size. The soil hydraulic conductivity increased with decreasing particle sizes apart from biochar particles <0.063mm which showed a significant (p&#8804;0.05) decrease compared to the larger particle sizes. The results clearly showed that both biochar intra-porosity and inter-porosity are important factors affecting soil hydraulic properties. Biochar interpores affected mainly hydraulic conductivity, both interpores and intrapores controlled soil water retention properties. Our results suggest that for a more effective increase in soil water retention in sandy loam and loamy sand, the use of hydrophilic biochar with high intra-porosity is recommended.

Download Full-text

Modeling root water uptake depth driven by climate and soil texture using a simple bucket model approach

10.5194/egusphere-egu21-16434 ◽

2021 ◽

Author(s):

Ruth Adamczewski ◽

Sven Westermann ◽

Anke Hildebrandt

Keyword(s):

Soil Water ◽

Hydraulic Properties ◽

Water Retention ◽

Root Water Uptake ◽

Rooting Depth ◽

Soil Hydraulic Properties ◽

Soil Water Retention ◽

Precipitation Patterns ◽

Biogeochemical Models ◽

Soil Hydraulic

Root water uptake (RWU) in grasslands is determined by species composition, climate and soil hydraulic properties. Generally, plant communities are adapted to their environment, showing different rooting patterns along climate gradients. Due to climate change, ecosystems are exposed to shifts in precipitation patterns and rising temperatures, causing the need to adapt rooting strategies. RWU is mainly driven by plant transpiration and soil hydraulic status in the rooting zone. Soil hydraulic properties depend strongly on soil texture, which has been observed to influence rooting depth, increasing the root length from fine to coarse soils. Secondly, precipitation patterns affect the typical soil moisture status, and subsequently the rooting depth. Global models suggest that in dry environments RWU should move deeper, to enhance the plant available soil water. However, few studies have at the same time considered the effect of climate and soil properties on RWU depth, although soil properties vary substantially and probably more than precipitation patterns due to climate change.Biogeochemical models suffer from uncertainty in subsurface hydrological processes, RWU being an important part of it. Thus, ecohydrological models are needed for an integration in larger context biogeochemical models. The trend of ecological models is towards high parameterized models, implying high uncertainty and challenging calibration for those parameters. Especially in the subsurface, parameters are often unknown and are usually impossible to derive from direct measurements. In this project, a simple, parsimonious bucket model was implemented, solving the water balance equation for a multi-layer soil profile. The objective of this work is to predict maximum required RWU depth required to satisfy potential evapotranspiration across established experimental grassland sites with different climate and soil water retention properties. For this we use soil moisture measurements, textures and hydraulic properties determined in three grassland sites of the Nutrient-Network (NutNet) across a climate gradient. We test the sensitivity of the model towards climate and soil hydraulic parameters. First model results show a high sensitivity of RWU depth besides to dynamics to climate, also to soil water retention determined by texture and organic matter content in the soils.

Download Full-text