The role of soil resistance in determining water uptake by plant root systems

Soil Research ◽  
1983 ◽  
Vol 21 (4) ◽  
pp. 571 ◽  
Author(s):  
NR Hulugalle ◽  
ST Willatt
Keyword(s):  
Water Stress ◽  
Hydraulic Conductivity ◽  
Water Uptake ◽  
Plant Root ◽  
Soil Water Potential ◽  
Root Systems ◽  
Plant Roots ◽  
Soil Resistance ◽  
Plant Root Systems

Resistance to water flow in plant roots has been suggested as a significant factor limiting water uptake by plants. The results of previous experiments have been used to show that soil resistance may be more significant than has recently been suggested, particularly in soils of low hydraulic conductivity and where root density is low. As the technique used to determine soil resistance relies on hydraulic conductivity, the latter may be more appropriate as an indicator of water stress than soil water potential.

Soil and plant resistances to water absorption by plant root systems

1979 ◽  
Vol 30 (2) ◽  
pp. 279 ◽  
Author(s):  
GJ Burch
Keyword(s):  
Water Absorption ◽  
Root System ◽  
Soil Water ◽  
Water Movement ◽  
Plant Root ◽  
Unit Length ◽  
Water Flux ◽  
Soil Water Potential ◽  
Root Systems ◽  
Soil Resistance

A study of water absorption by root systems of two herbage species, white clover (Trifolium repens L.) and tall fescue (Festuca arundinacea Schreb.), was used to partition the resistances to water flux between the soil and plant. A large and almost constant plant resistance influenced the pattern of water absorption until the soil resistance reached about 1.5 x 103 MPa s cm-3. This corresponded to an extraction of almost 80% of the available soil water. Water absorption from progressively deeper soil layers showed no evidence of any substantial resistance to water flux through the root xylem. Therefore, in wet soils, water movement into and through a root system is predominantly influenced by a large resistance to the radial water flux through root tissues outside the xylem. The radial resistance values for unit (cm) length of root were 6.49 x 106 and 6.54 x 106 MPa s cm-2 for clover and fescue respectively. A model of water uptake has been described which introduces two modified parameters for integrating the soil water potential (ψ) and the soil-root conductance (κ), over an entire root system. This study, along with other evidence from the literature, would indicate that for unit length of root the radial resistance to water absorption is reasonably similar, not only for an entire root system but also for a number of different species. An underestimation of the radial soil resistance (Rsr) to water absorption suggests that a root contact resistance (Rc) exists which could be due to the shrinkage of the soil or root, or both, with drying of the soil. This effect caused an increase in resistance to water absorption of about 48 x Rsr for fescue and 71 x Rsr for clover. This difference in Rc between the two species was attributed to a contrast in root morphology, especially a difference in the average root diameters of the two species.

scholarly journals Implementing small scale processes at the soil-plant interface – the role of root architectures for calculating root water uptake profiles

2010 ◽  
Vol 14 (2) ◽  
pp. 279-289 ◽  
Author(s):  
C. L. Schneider ◽  
S. Attinger ◽  
J.-O. Delfs ◽  
A. Hildebrandt
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Water Uptake ◽  
Soil Water Potential ◽  
Root Systems ◽  
Root Water Uptake ◽  
Bulk Soil ◽  
Small Scale ◽  
Sink Term

Abstract. In this paper, we present a stand alone root water uptake model called aRoot, which calculates the sink term for any bulk soil water flow model taking into account water flow within and around a root network. The boundary conditions for the model are the atmospheric water demand and the bulk soil water content. The variable determining the plant regulation for water uptake is the soil water potential at the soil-root interface. In the current version, we present an implementation of aRoot coupled to a 3-D Richards model. The coupled model is applied to investigate the role of root architecture on the spatial distribution of root water uptake. For this, we modeled root water uptake for an ensemble (50 realizations) of root systems generated for the same species (one month old Sorghum). The investigation was divided into two Scenarios for aRoot, one with comparatively high (A) and one with low (B) root radial resistance. We compared the results of both aRoot Scenarios with root water uptake calculated using the traditional Feddes model. The vertical rooting density profiles of the generated root systems were similar. In contrast the vertical water uptake profiles differed considerably between individuals, and more so for Scenario B than A. Also, limitation of water uptake occurred at different bulk soil moisture for different modeled individuals, in particular for Scenario A. Moreover, the aRoot model simulations show a redistribution of water uptake from more densely to less densely rooted layers with time. This behavior is in agreement with observation, but was not reproduced by the Feddes model.

scholarly journals Implementing small scale processes at the soil-plant interface – the role of root architectures for calculating root water uptake profiles

2009 ◽  
Vol 6 (3) ◽  
pp. 4233-4264 ◽  
Author(s):  
C. L. Schneider ◽  
S. Attinger ◽  
J.-O. Delfs ◽  
A. Hildebrandt
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Water Uptake ◽  
Soil Water Potential ◽  
Root Systems ◽  
Root Water Uptake ◽  
Bulk Soil ◽  
Small Scale ◽  
Sink Term

Abstract. In this paper, we present a stand alone root water uptake model called aRoot, which calculates the sink term for any bulk soil water flow model taking into account water flow within and around a root network. The boundary conditions for the model are the atmospheric water demand and the bulk soil water content. The variable determining the plant regulation for water uptake is the soil water potential at the soil-root interface. In the current version, we present an implementation of aRoot coupled to a 3-D Richards model. The coupled model is applied to investigate the role of root architecture on the spatial distribution of root water uptake. For this, we modeled root water uptake for an ensemble (50 realizations) of root systems generated for the same species (one month old Sorghum). The investigation was divided into two Scenarios for aRoot, one with comparatively high (A) and one with low (B) root radial resistance. We compared the results of both aRoot Scenarios with root water uptake calculated using the traditional Feddes model. The vertical rooting density profiles of the generated root systems were similar. In contrast the vertical water uptake profiles differed considerably between individuals, and more so for Scenario B than A. Also, limitation of water uptake occurred at different bulk soil moisture for different modeled individuals, in particular for Scenario A. Moreover, the aRoot model simulations show a redistribution of water uptake from more densely to less densely rooted layers with time. This behavior is in agreement with observation, but was not reproduced by the Feddes model.

The role of plant root systems in evolutionary adaptation

2019 ◽  
pp. 55-80 ◽  
Author(s):  
Vinay Shekhar ◽  
Dorothee Stӧckle ◽  
Martha Thellmann ◽  
Joop E.M. Vermeer
Keyword(s):  
Plant Root ◽  
Root Systems ◽  
Evolutionary Adaptation ◽  
Plant Root Systems

scholarly journals Model Test of the Reinforcement of Surface Soil by Plant Roots under the Influence of Precipitation

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Hengxing Wang ◽  
Yulong He ◽  
Zufeng Shang ◽  
Chunpeng Han ◽  
Yilu Wang
Keyword(s):  
Water Content ◽  
Model Test ◽  
Surface Soil ◽  
Plant Root ◽  
Root Systems ◽  
Reinforced Soil ◽  
Plant Roots ◽  
Interfacial Friction ◽  
Negative Power ◽  
Pull Out

We present the results of the reinforcement of plant root systems in surface soil in a model test to simulate actual precipitation conditions. In the test, Eleusine indica was selected as herbage to reinforce the soil. Based on the various moisture contents of plant roots in a pull-out test, a fitting formula describing the interfacial friction strength between the roots and soil and soil moisture content was obtained to explain the amount of slippage of the side slope during the process of rainfall. The experimental results showed that the root systems of plants successfully reinforced soil and stabilized the water content in the surface soil of a slope and that the occurrence time of landslides was delayed significantly in the grass-planting slope model. After the simulated rainfall started, the reinforcement effect of the plant roots changed. As the rainfall increased, the interfacial friction between the roots and the soil exhibited a negative power function relationship with the water content. These conclusions can be used as a reference for the design of plant slope protection and reinforcement.

Basin Hydrology and Plant Root Systems

1990 ◽  
pp. 243-292 ◽  
Author(s):  
James P. Dobrowolski ◽  
Martyn M. Caldwell ◽  
James H. Richards
Keyword(s):  
Plant Root ◽  
Root Systems ◽  
Basin Hydrology ◽  
Plant Root Systems
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