Supplementary material to "Impacts of experimental conditions on soil saturated hydraulic conductivity in conventional and conservation tillage practices"

Impacts of experimental conditions on soil saturated hydraulic conductivity in conventional and conservation tillage practices

10.5194/soil-2021-118 ◽

2021 ◽

Author(s):

Kaihua Liao ◽

Xiaoming Lai ◽

Qing Zhu

Keyword(s):

Hydraulic Conductivity ◽

Large Scale ◽

Conservation Tillage ◽

Meta Analysis ◽

Soil Layer ◽

Conventional Tillage ◽

Saturated Hydraulic Conductivity ◽

Mean Annual Temperature ◽

Experimental Conditions ◽

Conversion Period

Abstract. The saturated hydraulic conductivity (Ksat) is a key soil hydraulic property governing agricultural production. However, the influence of conversion from conventional tillage (CT) to conservation tillage (CS) (including no tillage (NT) and reduced tillage (RT)) on Ksat of soils is not well understood and still debated. In this study, we applied a global meta-analysis method to synthesize 201 paired observations for soil Ksat from 59 published studies, and investigated factors influencing the effects of conversion to CS on Ksat. Results showed that the Ksat measured by hood infiltrometer, tension disc infiltrometer, and Guelph permeameter produced a similar pattern under CS practices, with non-significant (p > 0.05) increase of 6.6 %, 3.6 % and 4.9 %, respectively. However, conversion to CS significantly (p < 0.05) increased Ksat by 32.0 % for ring infiltrometer, while it decreased Ksat by 3.2 % for constant/falling head (p > 0.05). Soil layer, CS type and soil texture had no significant (p > 0.05) effects on the influence of conversion to CS on the Ksat, but the Ksat under CS showed a greater increase for a longer conversion period (time since conversion). In addition, mean annual temperature (MAT) was found to be an important driver controlling the response of Ksat to tillage conversion at the large scale. These findings suggested that quantifying the effects of tillage conversion on soil Ksat needed to consider experimental conditions, especially the measurement technique and conversion period.

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Characterization of stony soils' hydraulic conductivity using laboratory and numerical experiments

SOIL ◽

10.5194/soil-2-421-2016 ◽

2016 ◽

Vol 2 (3) ◽

pp. 421-431 ◽

Cited By ~ 9

Author(s):

Eléonore Beckers ◽

Mathieu Pichault ◽

Wanwisa Pansak ◽

Aurore Degré ◽

Sarah Garré

Keyword(s):

Hydraulic Conductivity ◽

Water Flow ◽

Predictive Models ◽

Laboratory Experiments ◽

Saturated Hydraulic Conductivity ◽

Experimental Conditions ◽

Rock Fragments ◽

Unsaturated Hydraulic Conductivity ◽

The One ◽

The Impact

Abstract. Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature describing the impact of stones on the hydraulic conductivity of a soil is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow, and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory experiments and numerical simulations involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned predictive models. Our study suggests that it might be ill-founded to consider that stones only reduce the volume available for water flow. We pointed out several factors of the saturated hydraulic conductivity of stony soils that are not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, laboratory experiments show that an increasing stone content can counteract and even overcome the effect of a reduced volume in some cases: we observed an increase in saturated hydraulic conductivity with volume of inclusions. These differences are mainly important near to saturation. However, comparison of results from predictive models and our experiments in unsaturated conditions shows that models and data agree on a decrease in hydraulic conductivity with stone content, even though the experimental conditions did not allow testing for stone contents higher than 20 %.

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Interpretation of ponded infiltration data using numerical experiments

Journal of Hydrology and Hydromechanics ◽

10.1515/johh-2016-0020 ◽

2016 ◽

Vol 64 (3) ◽

pp. 289-299 ◽

Cited By ~ 7

Author(s):

Michal Dohnal ◽

Tomas Vogel ◽

Jaromir Dusek ◽

Jana Votrubova ◽

Miroslav Tesar

Keyword(s):

Hydraulic Conductivity ◽

Saturated Hydraulic Conductivity ◽

Experimental Conditions ◽

Insertion Depth ◽

Retention Capacity ◽

Soil Layering ◽

Soil Hydraulic ◽

The Impact ◽

Infiltration Experiment

AbstractPonded infiltration experiment is a simple test used for in-situ determination of soil hydraulic properties, particularly saturated hydraulic conductivity and sorptivity. It is known that infiltration process in natural soils is strongly affected by presence of macropores, soil layering, initial and experimental conditions etc. As a result, infiltration record encompasses a complex of mutually compensating effects that are difficult to separate from each other. Determination of sorptivity and saturated hydraulic conductivity from such infiltration data is complicated. In the present study we use numerical simulation to examine the impact of selected experimental conditions and soil profile properties on the ponded infiltration experiment results, specifically in terms of the hydraulic conductivity and sorptivity evaluation. The effect of following factors was considered: depth of ponding, ring insertion depth, initial soil water content, presence of preferential pathways, hydraulic conductivity anisotropy, soil layering, surface layer retention capacity and hydraulic conductivity, and presence of soil pipes or stones under the infiltration ring. Results were compared with a large database of infiltration curves measured at the experimental site Liz (Bohemian Forest, Czech Republic). Reasonably good agreement between simulated and observed infiltration curves was achieved by combining several of factors tested. Moreover, the ring insertion effect was recognized as one of the major causes of uncertainty in the determination of soil hydraulic parameters.

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Near-saturated soil hydraulic conductivity and pore characteristics as influenced by conventional and conservation tillage practices in North-West Himalayan region, India

International Soil and Water Conservation Research ◽

10.1016/j.iswcr.2021.01.001 ◽

2021 ◽

Author(s):

Deepak Singh ◽

Alok Kumar Mishra ◽

Sridhar Patra ◽

Sankar Mariappan ◽

Nisha Singh

Keyword(s):

Hydraulic Conductivity ◽

Conservation Tillage ◽

Saturated Soil ◽

Himalayan Region ◽

Pore Characteristics ◽

Soil Hydraulic Conductivity ◽

North West ◽

Tillage Practices ◽

Soil Hydraulic

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Numerical analysis of ponded infiltration experiment under different experimental conditions

Soil and Water Research ◽

10.17221/1368-swr ◽

2010 ◽

Vol 4 (Special Issue 2) ◽

pp. S22-S27 ◽

Cited By ~ 7

Author(s):

J. Dušek ◽

M. Dohnal ◽

T. Vogel

Keyword(s):

Finite Element ◽

Hydraulic Conductivity ◽

Soil Surface ◽

Infiltration Rate ◽

Element Model ◽

Saturated Hydraulic Conductivity ◽

Finite Element Mesh ◽

Experimental Conditions ◽

Element Mesh ◽

Double Ring

One of the most important properties, affecting the flow regime in the soil profile, is the topsoil saturated hydraulic conductivity (Ks). The laboratory-determined Ks often fails to characterise properly the respective field value; the Ks lab estimation requires labour intensive sampling and fixing procedures, difficult to follow in highly structured and stony soils. Thus, simple single- or double-ring ponded infiltration experiments are frequently performed in situ to obtain the field scale information required. In the present study, several important factors, affecting the infiltration rate during the infiltration experiments, are analysed using three-dimensional axisymmetric finite-element model S2D. The examined factors include: (1) the diameter of the infiltration ring, (2) the depth of water in the ring, (3) the depth of the ring insertion under the soil surface, (4) the size and the shape of the finite-element mesh near the ring wall, and (5) the double- vs. single-ring setup. The analysis suggests that the depth of the ring insertion significantly influences the infiltration rate. The simulated infiltration rates also exhibit high sensitivity to the shape of the finite-element mesh near the ring wall. The steady-state infiltration rate, even when considering a double-ring experiment, is significantly higher than the topsoil saturated hydraulic conductivity. The change of the water depth in the outer ring has only a small impact on the infiltration rate in the inner ring.

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