Prediction of Soil Hydraulic Conductivity at Saturation using Air Permeability at Any Individual Soil Water Content

2019 ◽  
Vol 23 (12) ◽  
pp. 5226-5234
Author(s):  
Mehdi Rahmati ◽  
Mohammad Reza Neyshaboury ◽  
Panah Mohammadi
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Air Permeability ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

Libardi's method refinement for soil hydraulic conductivity measurement

Soil Research ◽  
2001 ◽  
Vol 39 (4) ◽  
pp. 851 ◽  
Author(s):  
P. L. Libardi ◽  
P. L. Libardi ◽  
K. Reichardt ◽  
K. Reichardt
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Conductivity Measurement ◽  
Soil Surface ◽  
Hydraulic Gradient ◽  
Saturated Soil ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

The method of Libardi to estimate soil hydraulic conductivity in the field, during the redistribution of soil water, is discussed and improved. It is shown that if the saturated soil water content is measured at the soil surface, values at any other depth can be calculated from the database used to compute hydraulic conductivity. Since the saturated soil water content is difficult to measure and critical to the establishment of the hydraulic conductivity functions, this is an important refinement of the method. It is also shown that the unit hydraulic gradient assumption, which is part of the methodology, does not introduce significant errors in the estimation of soil hydraulic conductivity.

Tree/pasture interactions at a range of tree densities in an agroforestry experiment. III. Water uptake in relation to soil hydraulic conductivity and rooting patterns

1990 ◽  
Vol 41 (4) ◽  
pp. 709 ◽  
Author(s):  
J Eastham ◽  
CW Rose ◽  
DM Cameron ◽  
SJ Rance ◽  
T Talsma ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Root Length ◽  
Tree Density ◽  
Soil Hydraulic Conductivity ◽  
Tree Transpiration ◽  
Rooting Patterns ◽  
Soil Hydraulic ◽  
Water Contents

Eucalyptus grandis was planted in a Nelder fan design in November 1983 into a previously established pasture dominated by Setaria sphacelata cv. Kazungula, at the CSIRO Sanford Pasture Research Station, Queensland, Australia. Nine concentric rings of 18 trees were planted at radii of 4.4-61.6 m, giving a range of tree densities which decreased from 3580 to 42 stems/ha. Tree transpiration was studied at three tree densities (2150, 304 and 82 stems/ha, representing high, medium and low densities) over a 'drought' period of approximately 1 yr (Nov. 1985-Sep. 1986) and related to rooting patterns and soil hydraulic properties. Over the range of soil water contents studied, the ratio of tree transpiration rate to equilibrium evaporation rate (T/Esub(eq)) decreased linearly with decreasing mean soil water content at each tree density. To investigate the effects of soil hydraulic conductivity and root length density on the total transpirational flux, overall soil conductances (Ksub(s)) were calculated, with soil conductance in each horizon weighted according to the length of root in that horizon. At each tree density, decreases in the ratio T/Esub(eq) were related to decreases in ln Ksub(s) measured at 1.2 m from the stem. A more rapid decrease in T/Esub(eq) with decrease in water content observed at the low tree density was attributed to a greater decrease in Ksub(s) as mean water contents decreased. The greater decrease in Ksub(s) at low tree densities was associated with a larger proportion of water extracted and a higher proportion of total root length in surface soil horizons, which showed a greater decrease in hydraulic conductivity than subsoil horizons for the same decrease in water content.

A parameterised equation to estimate soil hydraulic conductivity in the field

Soil Research ◽  
2004 ◽  
Vol 42 (3) ◽  
pp. 283 ◽  
Author(s):  
K. Reichardt ◽  
L. C. Timm ◽  
O. O. S. Bacchi ◽  
J. C. M. Oliveira ◽  
D. Dourado-Neto
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Water Dynamics ◽  
Water Drainage ◽  
Soil Water Dynamics ◽  
Soil Hydraulic Conductivity ◽  
Exponential Character ◽  
Simplifying Assumptions ◽  
Soil Hydraulic

The description of soil water dynamics using the Darcy–Buckingham approach involves the determination and use of soil hydraulic conductivity K v. soil water content θ functions. Many of the methods developed for the measurement of K are based on simplifying assumptions, such as the unit gradient and the choice of fixed models for the K(θ) relation. The need of quick, simple, and inexpensive methods to measure K(θ) in the field using a large number of replicates has also led soil physicists to develop simple methods. This paper presents a procedure that makes use of parameters of equations used to explain the internal water drainage process, and that naturally leads to the exponential character of the K(θ) relation. Results show that the parameterised equation represents a more rigorous estimation of K(θ), compared with the methods that assume unit gradient.

The WormEx I Experiment: Effects of biopores and earthworm holes on soil hydraulic conductivity, sorptivity and macroscopic capillary length

2020 ◽  
Author(s):  
Dario Pezzotti ◽  
Marco Peli ◽  
Roberto Ranzi ◽  
Stefano Barontini
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Conditions ◽  
Pressure Potential ◽  
Capillary Length ◽  
Soil Hydraulic Conductivity ◽  
Adverse Conditions ◽  
Soil Hydraulic ◽  
Infiltration Tests

<p>The WormEx I Experiment was launched on 9 March 2016 to investigate the effects of biopores and earthworms holes on soil-water constitutive laws.<br>Particularly, changes in the soil hydraulic conductivity, in the soil sorptivity and in the macroscopic capillary length were evaluated in different soil conditions, by means of infiltrometric tests performed in a shallow anthropogenic soil of the Central Italian Alps (Cividate Camuno, Italy).<br>About 50 field infiltration tests were performed by means of a tension infiltrometer (TI) and by means of a small single ring infiltrometer, in view of applying the simplified BEST method (Beerkan Estimation of Soil Transfer parameters).<br>The worms presence was accounted for by counting worms' castings in 1 m<sup>2</sup> experimental plots, and it was considered a proxy of the biogenic activity.<br>Various meteorological conditions and various conditions of the presence of worms' castings were sampled during a period of three years.<br>Obtained results highlight how soil hydrological properties change depending on the biopores presence.</p><p>As a result, the hydraulic conductivity greatly increased in presence of soil biopores, both in ponding and in near-saturation conditions.<br>Conductivity at saturation increased on average by 45% (TI method), between great and small presence of earthworms' holes.<br>Considering soil conditions that stimulate the biological activity (e.g. the previous days precipitation and the great water content at the beginning of the infiltration tests), the conductivity at saturation increased more, i.e. by 85% (TI) and by 105% (BEST) on average.<br>The increase is even more relevant passing from adverse conditions (low castings number and small initial soil-water content) to optimal conditions (high castings number and great initial soil-water content).<br>In these cases average increments are more than 200% (TI).</p><p>Also the hydraulic conductivity of the nearly saturated soil, with pressure potential ranging between -5 cm and  0 cm, meaningfully increased in case of biopores presence.<br>The greatest (relative) increase of the soil hydraulic conductivity was observed in most of the cases at a pressure potential of -2 cm.</p><p>Sorptivity meaningfully increased from low to high wormholes number (45% at saturation) and from optimal to adverse conditions (114% at saturation).<br>As for the hydraulic conductivity, this increase was even greater nearby ponding conditions.<br>Field-tests results changed greatly depending on time and space: great standard deviations were observed for both hydraulic conductivity and sorptivity at all the values of pressure potential.</p><p>The macroscopic capillary length λ<sub>c</sub>, which provides concise information about the soil attitude to diffusion, determined by numerically evaluating the subtended area to the experimental hydraulic-conductivity curve, also evidenced the presence of earthworms' burrows, ranging from 16.9 mm to  11.6 mm in optimal and adverse conditions respectively.</p>

Root effects on soil water and hydraulic properties

Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
Horst Gerke ◽  
Rolf Kuchenbuch
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Root Effects

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

scholarly journals Effect of Biochar Application and Re-Application on Soil Bulk Density, Porosity, Saturated Hydraulic Conductivity, Water Content and Soil Water Availability in a Silty Loam Haplic Luvisol

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1005 ◽  
Author(s):  
Lucia Toková ◽  
Dušan Igaz ◽  
Ján Horák ◽  
Elena Aydin
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Bulk Density ◽  
Relative Increase ◽  
Saturated Hydraulic Conductivity ◽  
Soil Drought ◽  
Silty Loam

Due to climate change the productive agricultural sectors have started to face various challenges, such as soil drought. Biochar is studied as a promising soil amendment. We studied the effect of a former biochar application (in 2014) and re-application (in 2018) on bulk density, porosity, saturated hydraulic conductivity, soil water content and selected soil water constants at the experimental site in Dolná Malanta (Slovakia) in 2019. Biochar was applied and re-applied at the rates of 0, 10 and 20 t ha−1. Nitrogen fertilizer was applied annually at application levels N0, N1 and N2. In 2019, these levels were represented by the doses of 0, 108 and 162 kg N ha−1, respectively. We found that biochar applied at 20 t ha−1 without fertilizer significantly reduced bulk density by 12% and increased porosity by 12%. During the dry period, a relative increase in soil water content was observed at all biochar treatments—the largest after re-application of biochar at a dose of 20 t ha−1 at all fertilization levels. The biochar application also significantly increased plant available water. We suppose that change in the soil structure following a biochar amendment was one of the main reasons of our observations.

Modelling leaching and recharge in a bare transitional red-brown earth ponded with low salinity water in summer

1994 ◽  
Vol 34 (7) ◽  
pp. 1085 ◽  
Author(s):  
L Cai ◽  
SA Prathapar ◽  
HG Beecher
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Soil Surface ◽  
Saturated Hydraulic Conductivity ◽  
Rate Dependent ◽  
Water And Salt Movement ◽  
Winter Fallow

A modelling study was conducted to evaluate water and salt movement within a transitional red-brown earth with saline B horizon soil when such waters are used for ponding in summer. The model was calibrated using previously published experimental data. The calibrated model was used to evaluate the effect of depth to watertable, saturated hydraulic conductivity, and ponding water salinity on infiltration, water and salt movement within the soil profile, and recharge. The study showed that when initial soil water content and the saturated hydraulic conductivity (Ks) are low, infiltrating water will be stored within the soil profile even in the absence of a shallow watertable. Once the soil water content is high, however, recharge will be significant in winter, even if there is no net infiltration at the soil surface. Infiltration rates depend more on Ks than the depth to watertable if it is at, or below, 1.5 m from the soil surface. When Ks is high, recharge under ponding will be higher than that under winter fallow. Subsequent ponding in summer and fallow in winter tend to leach salts from the soil profile, the leaching rate dependent on Ks. During winter fallow, due to net evaporation, salts tend to move upwards and concentrate near the soil surface. In the presence of shallow watertables, leached salts tend to concentrate at, or near, the watertable.

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