Hydraulic Conductivity Changes in Soybean Plant-Soil System with Decreasing Soil Volumetric Water Content

2016 ◽  
Vol 30 (6) ◽  
pp. 713-723 ◽  
Author(s):  
Xia Li ◽  
Thomas R. Sinclair ◽  
Laleh Bagherzadi
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Volumetric Water Content ◽  
Soybean Plant ◽  
Soil System ◽  
Soil Volumetric Water Content ◽  
Plant Soil

Hyphal colonization of Rhizophagus irregularis increases unsaturated hydraulic conductivity of a loamy sand distant from roots

2021 ◽  
Author(s):  
Michael Bitterlich ◽  
Richard Pauwels
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Hydraulic Properties ◽  
Volumetric Water Content ◽  
Rhizophagus Irregularis ◽  
Loamy Sand ◽  
Soil Hydraulic Properties ◽  
Unsaturated Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Root Exclusion

<p>Hydraulic properties of mycorrhizal soils have rarely been reported and difficulties in directly assigning potential effects to hyphae of arbuscular mycorrhizal fungi (AMF) arise from other consequences of AMF being present, i.e. their influence on growth and water consumption rates of their host plants that both also influence soil hydraulic properties.</p><p>We assumed that the typical nylon meshes used for root-exclusion experiments in mycorrhizal research can provide a dynamic hydraulic barrier. It is expected that the uniform pore size of the rigid meshes causes a sudden hydraulic decoupling of the enmeshed inner volume from the surrounding soil as soon as the mesh pores become air-filled. Growing plants below the soil moisture threshold for hydraulic decoupling would minimize plant-size effects on root-exclusion compartments and allow for a more direct assignment of hyphal presence to modulations in soil hydraulic properties.</p><p>We carried out water retention and hydraulic conductivity measurements with two tensiometers introduced in two different heights in a cylindrical compartment (250 cm³) containing a loamy sand, either with or without the introduction of a 20 µm nylon mesh equidistantly between the tensiometers. Introduction of a mesh reduced hydraulic conductivity across the soil volumes by two orders of magnitude from 471 to 6 µm d<sup>-1</sup> at 20% volumetric water content.</p><p>We grew maize plants inoculated or not with Rhizophagus irregularis in the same soil in pots that contained root-exclusion compartments while maintaining 20% volumetric water content. When hyphae were present in the compartments, water potential and unsaturated hydraulic conductivity increased for a given water content compared to compartments free of hyphae. These differences increased with progressive soil drying.</p><p>We conclude that water extractability from soils distant to roots can be facilitated under dry conditions when AMF hyphae are present.</p><p> </p>

scholarly journals Water-Use Characteristics and Physiological Response of Moso Bamboo to Flash Droughts

2019 ◽  
Vol 16 (12) ◽  
pp. 2174 ◽  
Author(s):  
Minxia Zhang ◽  
Shulin Chen ◽  
Hong Jiang ◽  
Yong Lin ◽  
Jinmeng Zhang ◽  
...  
Keyword(s):  
Water Content ◽  
Water Use ◽  
Forest Canopy ◽  
Stand Density ◽  
Water Shortage ◽  
Volumetric Water Content ◽  
Moso Bamboo ◽  
Extreme Drought ◽  
Soil Volumetric Water Content ◽  
The Stability

Frequent flash droughts can rapidly lead to water shortage, which affects the stability of ecosystems. This study determines the water-use characteristics and physiological mechanisms underlying Moso bamboo response to flash-drought events, and estimates changes to water budgets caused by extreme drought. We analyzed the variability in forest canopy transpiration versus precipitation from 2011–2013. Evapotranspiration reached 730 mm during flash drought years. When the vapor pressure deficit > 2 kPa and evapotranspiration > 4.27 mm·day−1, evapotranspiration was mainly controlled through stomatal opening and closing to reduce water loss. However, water exchange mainly occurred in the upper 0–50 cm of the soil. When soil volumetric water content of 50 cm was lower than 0.17 m3·m−3, physiological dehydration occurred in Moso bamboo to reduce transpiration by defoliation, which leads to water-use efficiency decrease. When mean stand density was <3500 trees·ha−1, the bamboo forest can safely survive the flash drought. Therefore, we recommend thinning Moso bamboo as a management strategy to reduce transpiration in response to future extreme drought events. Additionally, the response function of soil volumetric water content should be used to better simulate evapotranspiration, especially when soil water is limited.

scholarly journals Determining the Unsaturated Hydraulic Conductivity of Remoulded Loess with Filter Paper Method and Soil Column Seepage Test

2021 ◽  
Author(s):  
Wenwu Chen ◽  
Quanquan Jia ◽  
Peng Liu ◽  
Yanmei Tong
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Filter Paper ◽  
Characteristic Curve ◽  
Soil Column ◽  
Volumetric Water Content ◽  
Experimental Results ◽  
Paper Test ◽  
Unsaturated Hydraulic Conductivity ◽  
The One

Abstract Loess is very widely distributed, and the unsaturated hydraulic conductivity of loess is related to many engineering issues. In order to determine the unsaturated hydraulic conductivity of remolded loess more conveniently and at a lower cost, filter paper test and soil column seepage test were carried out. The results indicate that in the one-dimensional soil column seepage process, the unsaturated hydraulic conductivity of loess increases with the increase of the volumetric water content, and as the seepage time continues, the unsaturated hydraulic conductivity of loess at different depths gradually becomes uniform. The changes in the microstructure indicate that the collapsible settlement will occur during the seepage process, which will reduce the unsaturated hydraulic conductivity of the underlying loess to a certain extent. Compared with the experimental results, the soil hydraulic conductivity curve (SHCC) obtained by the van Genuchten-Mualem model (VG-M model) underestimates the magnitude of unsaturated hydraulic conductivity in the part with a low volumetric water content (< 20%). and the Childs ༆ Collis-George model (CCG model) has more consistent results with the experimental results because it is based on more segments of the soil-water characteristic curve (SWCC).

scholarly journals Field Monitoring-Based and Theoretical Analysis of Baota Mountain Landslide Stability

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yaming Tang ◽  
Heping Shu ◽  
Qiang Xue ◽  
Jiayun Wang ◽  
Wei Feng ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Depth ◽  
Limit Equilibrium ◽  
Stable State ◽  
Field Monitoring ◽  
Volumetric Water Content ◽  
Soil Volumetric Water Content ◽  
Limit Equilibrium Methods ◽  
Landslide Stability ◽  
Different Depths

Landslide is one of the most widely distributed surface morphological landscapes, and it can cause a series of major economic and human losses. Field monitoring and limit equilibrium methods were applied to investigate Baota Mountain landslide stability, and soil volumetric water content, different scales of rainfall data, and landslide displacements were monitored using various equipment. The theoretical factor of safety was also calculated for the landslide. Finally, the theoretical results were validated by monitoring data in the field. The results demonstrate that soil volumetric water content experienced the greatest change with time at a depth of 0.2 m and then 1 m; however, the change in soil volumetric water content was relatively small with time at a soil depth ranging from 2.0 m to 4.0 m. Soil volumetric water content also did not change with time at a soil depth of 5.0 m and below. In addition, the retardation effect was found in different depths of volumetric water content for continuous rainfall. The safety factors were 2.713 and 1.133 for landslide No. 1 and landslide No. 2, respectively. These results indicate that landslide No. 1 is relatively stable, but there is a probability of the occurrence of movement in landslide No. 2. The monitoring displacement data indicate that landslide No.1 was in a relatively stable state between 2008 and 2013, and this result was in accordance with the value of theoretical calculation. This study provided relevant parameters for numerical simulation of landslides in loess areas.

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