scholarly journals Impact of freeze-thaw cycles on soil structure and soil hydraulic properties

2021 ◽  
Author(s):  
Frederic Leuther ◽  
Steffen Schlüter
Keyword(s):  
Pore Structure ◽  
Soil Structure ◽  
Hydraulic Properties ◽  
Initial Structure ◽  
Soil Hydraulic Properties ◽  
Pore Connectivity ◽  
Freeze Thaw ◽  
Frost Action ◽  
Soil Hydraulic ◽  
The Impact

Abstract. The ploughing of soils in autumn drastically loosens the soil structure and at the same time reduces its stability against external stresses. A fragmentation of these artificially produced soil clods during winter time is often observed in areas with air temperatures fluctuating around the freezing point. Farmers benefit from the structural transformation by frost action in terms of better seedbed preparation and improved hydraulic connectivity. Previous studies have mainly focused on the effects of freezing and thawing on soil structure stability rather than on the impact on pore structure. From the pore perspective, it is still unclear (i) under which conditions frost action has a measurable effect on soil structure, (ii) what the impact on soil hydraulic properties is, and (iii) how many freeze-thaw cycles (FTCs) are necessary to induce soil structure changes. The aim of this study was to analyse the cumulative effects of multiple FTC on soil structure and soil hydraulic properties for two different textures and two different initial structures. A silt clay with a substantial amount of swelling clay minerals and a silty loam with less swell/shrink dynamics were either kept intact in undisturbed soil cores taken from the topsoil from a grassland or repacked with soil clods taken from a ploughed field nearby. FTCs were simulated under controlled conditions and changes in pore structure ≥ 48 µm were regularly recorded using X-ray µCT. After 19 FTCs, the impact on hydraulic properties were measured and the resolution of structural characteristics were enhanced towards narrow macro-pores with subsamples scanned at 10 µm. The impact of FTC on soil structure was dependent on the initial structure, soil texture, and the number of FTCs. Frost action induced a consolidation of repacked soil clods, resulting in a systematic reduction in pore sizes and macro-pore connectivity. In contrast, the macro-pore systems of the undisturbed soils were only slightly affected. Independent of the initial structure, a fragmentation of soil clods and macro-aggregates larger than 0.8 to 1.2 mm increased the connectivity of pores smaller than 0.5 to 0.8 mm. The fragmentation increased the unsaturated hydraulic conductivity of all treatments by a factor of 3 in a pF range of 2.0 to 2.5, while water retention was only slightly affected for the silt clay soil. Already 2 to 5 FTCs enforced a well-connected meso-pore system in all treatments, but it was steadily improved by further FTCs. This steady improvement in structural quality in terms of meso-pore connectivity is put at risk by milder winters in mid-latitudes due to global warming.

scholarly journals Impact of freeze–thaw cycles on soil structure and soil hydraulic properties

SOIL ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 179-191
Author(s):  
Frederic Leuther ◽  
Steffen Schlüter
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Structure ◽  
Hydraulic Properties ◽  
Initial Structure ◽  
Soil Hydraulic Properties ◽  
Freeze Thaw ◽  
Frost Action ◽  
Unsaturated Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
The Impact

Abstract. The ploughing of soils in autumn drastically loosens the soil structure and, at the same time, reduces its stability against external stresses. A fragmentation of these artificially produced soil clods during wintertime is often observed in areas with air temperatures fluctuating around the freezing point. From the pore perspective, it is still unclear (i) under which conditions frost action has a measurable effect on soil structure, (ii) what the impact on soil hydraulic properties is, and (iii) how many freeze–thaw cycles (FTCs) are necessary to induce soil structure changes. The aim of this study was to analyse the cumulative effects of multiple FTC on soil structure and soil hydraulic properties for two different textures and two different initial structures. A silt clay with a substantial amount of swelling clay minerals and a silty loam with fewer swell/shrink dynamics were either kept intact in undisturbed soil cores taken from the topsoil from a grassland or repacked with soil clods taken from a ploughed field nearby. FTCs were simulated under controlled conditions and changes in pore structure ≥ 48 µm were regularly recorded using X-ray µCT. After 19 FTCs, the impact on hydraulic properties were measured, and the resolution of structural characteristics were enhanced towards narrow macropores with subsamples scanned at 10 µm. The impact of FTC on soil structure was dependent on the initial structure, soil texture, and the number of FTCs. Frost action induced a consolidation of repacked soil clods, resulting in a systematic reduction in pore sizes and macropore connectivity. In contrast, the macropore systems of the undisturbed soils were only slightly affected. Independent of the initial structure, a fragmentation of soil clods and macro-aggregates larger than 0.8 to 1.2 mm increased the connectivity of pores smaller than 0.5 to 0.8 mm. The fragmentation increased the unsaturated hydraulic conductivity of all treatments by a factor of 3 in by a factor of 3 in a matrix potential range of −100 to −350 hPa, while water retention was only slightly affected for the silt clay soil. Already 2 to 5 FTCs enforced a well-connected pore system of narrow macropores in all treatments, but it was steadily improved by further FTCs. The implications of fewer FTCs during milder winters caused by global warming are twofold. In ploughed soils, the beneficial seedbed consolidation will be less intense. In grassland soils, which have reached a soil structure in dynamic equilibrium that has experienced many FTCs in the making, there is still a beneficial increase in water supply through increasing unsaturated hydraulic conductivity by continued FTCs that might also be less efficient in the future.

The impact of freeze-thaw-cycles on soil structure and soil hydraulic properties

2021 ◽  
Author(s):  
Frederic Leuther ◽  
Steffen Schlüter
Keyword(s):  
Soil Structure ◽  
Hydraulic Properties ◽  
Initial Structure ◽  
Silty Clay ◽  
Soil Hydraulic Properties ◽  
Pore System ◽  
Undisturbed Soil ◽  
Freeze Thaw ◽  
Soil Hydraulic ◽  
The Impact

<p>The ploughing of soils drastically alters soil structure and at the same time reduces its stability against external stresses. A fragmentation of these artificially produced soil clods during winter time is often observed in areas with air temperatures fluctuating around the freezing point. In this study, the cumulative effects of multiple freeze-thaw cycles (FTCs) on soil structure and soil hydraulic properties were analyzed for two different soil textures, a silty clay loam with a substantial amount of swelling clay minerals and a silty loam with less swell/shrink dynamics. The soil material was brought into two different initial states: (i) undisturbed soil cores taken from the topsoil from a grassland, and (ii) cylinders repacked with soil clods taken from a ploughed field nearby. FTCs were simulated under controlled conditions in the lab, changes in soil structure ≥48 µm were regularly recorded using X-ray µCT. After 19 FTCs, the impact on hydraulic properties were measured and the resolution of structural characteristics were increased to 10 µm by subsampling.</p><p>The effect of FTC on soil structure was found to be dependent on the initial structure, soil texture and number of FTCs. Freezing and thawing induced a consolidation of the repacked soil clods taken from both field sites, resulting in a systematic reduction in pore sizes and macro-pore connectivity. The macro-pore system of the undisturbed samples was only slightly affected. Fragmentation of soil elements larger than 0.8 to 1.2 mm increased the connectivity of pores smaller than 0.5 to 0.8 mm. Frost action increased the unsaturated hydraulic conductivity of all treatments, while the water retention was only slightly affected. This leads to the conclusion that multiple FTCs enforces a well-connected meso-pore system at the expense of a fragile macro-pore system. A change in soil structure that benefits farmers but could be reduced in the face of milder winters due to global warming.</p>

The impact of rural land management changes on soil hydraulic properties and runoff processes: results from experimental plots in upland UK

2013 ◽  
Vol 28 (4) ◽  
pp. 2617-2629 ◽  
Author(s):  
M. R. Marshall ◽  
C. E. Ballard ◽  
Z. L. Frogbrook ◽  
I. Solloway ◽  
N. McIntyre ◽  
...  
Keyword(s):  
Land Management ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Rural Land ◽  
Soil Hydraulic ◽  
Management Changes ◽  
The Impact ◽  
Experimental Plots

Effects of Sand Compaction and Mixing on Pore Structure and the Unsaturated Soil Hydraulic Properties

2016 ◽  
Vol 15 (8) ◽  
pp. vzj2015.10.0136 ◽  
Author(s):  
M.G. Mahmoodlu ◽  
A. Raoof ◽  
T. Sweijen ◽  
M. Th. van Genuchten
Keyword(s):  
Pore Structure ◽  
Unsaturated Soil ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic

Impact of plant roots and soil organisms on soil micromorphology and hydraulic properties

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
Radka Kodešová ◽  
Vít Kodeš ◽  
Anna Žigová ◽  
Jiří Šimůnek
Keyword(s):  
Pore Structure ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Organisms ◽  
Soil Hydraulic Properties ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
The Impact

AbstractA soil micromorphological study was performed to demonstrate the impact of soil organisms on soil pore structure. Two examples are shown here. First, the influence of earthworms, enchytraeids and moles on the pore structure of a Greyic Phaeozem is demonstrated by comparing two soil samples taken from the same depth of the soil profile that either were affected or not affected by these organisms. The detected image porosity of the organism-affected soil sample was 5 times larger then the porosity of the not-affected sample. The second example shows macropores created by roots and soil microorganisms in a Haplic Luvisol and subsequently affected by clay coatings. Their presence was reflected in the soil water retention curve, which displayed multiple S-shaped features as obtained from the water balance carried out for the multi-step outflow experiment. The dual permeability models implemented in HYDRUS-1D was applied to obtain parameters characterizing multimodal soil hydraulic properties using the numerical inversion of the multi-step outflow experiment.

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

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.

Microplastic enhances water repellency of soils

2020 ◽  
Author(s):  
Andreas Cramer ◽  
Ursula Bundschuh ◽  
Pascal Bernard ◽  
Mohsen Zarebanadkouki ◽  
Andrea Carminati
Keyword(s):  
Hydraulic Properties ◽  
Sessile Drop ◽  
Chemical Properties ◽  
Water Repellency ◽  
Terrestrial Ecosystems ◽  
Contact Angles ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
The Impact

<p>Soils are the largest sink of microplastic particles (MPP) in terrestrial ecosystems. However, there is little knowledge on the implication of MPP contaminating soils. In particular, we don’t know how MPP move and, on the other hand, how they affect soil hydraulic properties and soil moisture dynamics.</p><p>Among the expected effects of MPP on soil hydraulic properties is the likelihood that MPP enhances soil water repellency. This emerges from (1) the MPP surface chemical properties as well as (2) their surface physical properties like size and shape. Here, we tested mixtures of MPP and a model porous media. The Sessile Drop Method was applied and apparent contact angles were measured. We are able to show enlarged contact angles with rising concentrations of MPP. Already in relatively low concentrations of MPP the contact angels exhibit a steep increase and are rapidly reaching areas of super-hydrophobicity. Furthermore, we provide the physical explanation of the apparent contact angles resulting from the three-phase contact line between solid composite surfaces, water and air. The considered modes of a droplet lying on a surface are Wenzel, Cassie-Baxter and Young. The goal here was to differentiate between the involved surfaces building up the apparent contact angle and to pin down the impact of MPP in these systems.</p><p>Thinking about the implications of these results, an increased water repellency alters soil hydraulic properties towards less water content resulting in a shift in the water retention curve. Less water in soils especially at sites of high MPP concentrations leads to a limitation of degradation of MPP by hydrolysis. Additionally, microorganisms themselves and their enzymes cannot migrate in the liquid phase towards the MPP even elongating the process of natural purification.</p>

scholarly journals Effects of Land Use and Management on Soil Hydraulic Properties

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Ágota Horel ◽  
Eszter Tóth ◽  
Györgyi Gelybó ◽  
Ilona Kása ◽  
Zsófia Bakacsi ◽  
...  
Keyword(s):  
Land Use ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Negative Effects ◽  
Adaptation Measures ◽  
Temperature And Precipitation ◽  
Soil Hydraulic ◽  
Land Use And Management ◽  
The Impact ◽  
Effects Of Land Use

AbstractSoil hydraulic properties are among the most important parameters that determine soil quality and its capability to serve the ecosystem. Land use can significantly influence soil properties, including its hydraulic conditions; however, additional factors, such as changes in climate (temperature and precipitation), can further influence the land use effects on soil hydraulic properties. In order to develop possible adaptation measures and mitigate any negative effects of land use and climatic changes, it is important to study the impact of land use and changes in land use on soil hydraulic properties. In this paper, we summarize recent studies examining the effect of land use/land cover and the associated changes in soil hydraulic properties, mainly focusing on agricultural scenarios of cultivated croplands and different tillage systems.

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