Calibration of a water content reflectometer and soil water dynamics for an agroforestry practice

2010 ◽  
Vol 82 (1) ◽  
pp. 61-75 ◽  
Author(s):  
Ranjith P. Udawatta ◽  
Stephen H. Anderson ◽  
Peter P. Motavalli ◽  
Harold E. Garrett
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Agroforestry Practice

Soil water dynamics after fire in a Portuguese shrubland

2006 ◽  
Vol 15 (1) ◽  
pp. 99 ◽  
Author(s):  
Joaquim S. Silva ◽  
Francisco C. Rego ◽  
Stefano Mazzoleni
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Plant Community ◽  
Root Distribution ◽  
Control Plot ◽  
The Other ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Surface Layers ◽  
Before And After

This paper presents a study where soil water content (SW) was measured before and after an experimental fire in a shrubland dominated by Erica scoparia L. in Portugal. Two plots were established: one was kept as a control plot and the other was burned by an experimental fire in June 2001. Measurements were taken before fire (2000), and after fire (2001, 2002, and 2003) at six depths down to 170 cm, from June to December. Measurements before fire allowed comparison of the two plots in terms of the SW differential, using 2000 as a reference. Results for 2001 showed that SW decreased less during the drying season (June–September) and increased more during the wetting season (October–December) in the burned plot than in the control plot. The magnitude of these effects decreased consistently in 2002 and 2003, especially at surface layers. The maximum gain of SW for the total profile in the burned plot was estimated as 105.5 mm in 2001, 70.2 mm in 2002, and 35.6 mm in 2003. The present paper discusses the mechanisms responsible for the increase in SW taking into account the characteristics of the plant community, including the root distribution, and the results of other studies.

scholarly journals Quantitative high-resolution observations of soil water dynamics in a complicated architecture using time-lapse ground-penetrating radar

2015 ◽  
Vol 19 (3) ◽  
pp. 1125-1139 ◽  
Author(s):  
P. Klenk ◽  
S. Jaumann ◽  
K. Roth
Keyword(s):  
High Resolution ◽  
Water Content ◽  
Soil Water ◽  
Ground Penetrating Radar ◽  
Time Lapse ◽  
Test Site ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Capillary Fringe ◽  
Ground Penetrating

Abstract. High-resolution time-lapse ground-penetrating radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments that have been carried out at our artificial ASSESS test site and observed with surface-based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows the study of soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the feasibility of monitoring the dynamic shape of the capillary fringe reflection and (ii) the relative precision of monitoring soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.

Surface soil water dynamics in pastures in northern New South Wales. 1. Use of electrical resistance sensors

2004 ◽  
Vol 44 (3) ◽  
pp. 273 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Real Time ◽  
Surface Runoff ◽  
Electrical Resistance ◽  
New South ◽  
Water Dynamics ◽  
Continuous Data ◽  
Soil Water Dynamics ◽  
South Wales

Stored soil water may influence both the generation of surface runoff and the rate of evapotranspiration from pastures, which may be significant in northern New South Wales. Continuous data is essential to fully understand these processes in field studies. Electrical resistance sensors were used to capture continuous data and they were calibrated directly for soil water content (SWC), so as to provide quantitative data in real time. Calibration equations (logarithmic regression) were significantly different for a range of installation depths (2.5–20 cm). To�provide quantitative insight into soil water dynamics in studies of stored soil water, surface runoff, and evapotranspiration, real time data were collected at intervals ranging from 4 min to 24 h. Resistance sensors provided estimates of stored soil water (0–30 cm) that differed by up to 29% compared with estimates obtained from using a neutron moisture metre alone. In surface runoff studies, data collected at 4 min intervals showed that runoff was generated when soil water content was high. In studies of evapotranspiration, daily data were used to quantify different evapotranspiration rates (2.3–4.9 mm/day) and progressive depth of drying for a range of treatments. We concluded that data collected in real time using resistance sensors may be used to make better estimates of SWC and so improve the interpretation of surface runoff generation and evapotranspiration data.

Soil water dynamics and growth of perennial pasture species for dryland salinity control

2000 ◽  
Vol 40 (1) ◽  
pp. 37 ◽  
Author(s):  
S. J. Lolicato
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Lotus Corniculatus ◽  
Growth Patterns ◽  
Water Dynamics ◽  
Seasonal Growth ◽  
Long Term Effects ◽  
Soil Water Dynamics

Fortnightly soil water content measurements to a depth of 2.1 m under 4 cocksfoot cultivars, 2 phalaris cultivars, 2 lucerne cultivars and 1 Lotus corniculatus cultivar were used to compare soil profile drying and to define seasonal patterns of plant water use of the species over a 3-year period, on a duplex soil. Cultivars were also selected, within species groups, for varying seasonal growth patterns to assess this influence on soil water dynamics and growth. Over the 3-year period, treatments with the highest and lowest measures of profile soil water content were used to derive and compare values of maximum plant extractable water. Plots were maintained for a further 3 years, after which soil water content measurements in autumn were used to assess long-term effects of the treatments. The effect of seasonal growth patterns within a species was negligible; however, there were significant differences between species. Twenty-one months after pasture establishment, lucerne alone had a drying effect at 2.0 m depth and subsequently it consistently showed profiles with the lowest soil water content. Maximum plant extractable water was greatest for lucerne (230 mm), followed by phalaris (210 mm), Lotus corniculatus (200 mm) and cocksfoot (170 mm). Profiles with the lowest soil water content were associated with greater herbage growth and greater depths of water extraction. The soil water deficits developed by the treatments in autumn of the fourth year were similar to those measured in autumn of the seventh year, implying that a species-dependant equilibrium had been reached. Long-term rainfall data is used to calculate the probabilities of recharge occurring when rainfall exceeds maximum potential deficits for the different pasture species.

scholarly journals Soil water response to rainfall in a dune-interdune landscape in Horqin Sand Land, northern China

2019 ◽  
Vol 14 (No. 4) ◽  
pp. 229-239 ◽  
Author(s):  
Xueya Zhou ◽  
Dexin Guan ◽  
Jiabing Wu ◽  
Fenghui Yuan ◽  
Anzhi Wang ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Northern China ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Water Recharge ◽  
Sand Land ◽  
Horqin Sand Land ◽  
The Relationship

Soil water dynamic is considered an important process for water resource and plantation management in Horqin Sand Land, northern China. In this study, soil water content simulated by the SWMS-2D model was used to systematically analyse soil water dynamics and explore the relationship between soil water and rainfall among micro-landforms (i.e., top, upslope, midslope, toeslope, and bottomland) and 0–200 cm soil depths during the growing season of 2013 and 2015. The results showed that soil water dynamics in 0–20 cm depths were closely linked to rainfall patterns, whereas soil water content in 20–80 cm depths illustrated a slight decline in addition to fluctuations caused by rainfall. At the top position, the soil water content in different ranges of depths (20–40 and 80–200 cm) was near the wilting point, and hence some branches, and even entire plants exhibited diebacks. At the upslope or midslope positions, the soil water content in 20–80 or 80–200 cm depths was higher than at the top position. Soil water content was higher at the toeslope and bottomland positions than at other micro-landforms, and deep caliche layers had a positive feedback effect on shrub establishment. Soil water recharge by rainfall was closely related to rainfall intensity and micro-landforms. Only rainfalls &gt; 20 mm significantly increased water content in &gt; 40 cm soil depths, but deeper water recharge occurred at the toeslope position. A linear equation was fitted to the relationship between soil water and antecedent rainfall, and the slopes and R<sup>2</sup> of the equations were different among micro-landforms and soil depths. The linear equations generally fitted well in 0–20 and 20–40 cm depths at the top, upslope, midslope, and toeslope positions (R<sup>2</sup> value of about 0.60), with soil water in 0–20 cm depths showing greater responses to rainfall (average slope of 0.189). In 20–40 cm depths, the response was larger at the toeslope position, with a slope of 0.137. In 40–80 cm depths, a good linear fit with a slope of 0.041 was only recorded at the toeslope position. This study provides a soil water basis for ecological restoration in similar regions.  

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.

scholarly journals Quantitative high-resolution observations of soil water dynamics in a complicated architecture with time-lapse Ground-Penetrating Radar

2014 ◽  
Vol 11 (11) ◽  
pp. 12365-12404
Author(s):  
P. Klenk ◽  
S. Jaumann ◽  
K. Roth
Keyword(s):  
High Resolution ◽  
Water Content ◽  
Soil Water ◽  
Ground Penetrating Radar ◽  
Time Lapse ◽  
Test Site ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Capillary Fringe ◽  
Ground Penetrating

Abstract. High-resolution time-lapse Ground-Penetrating Radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments which have been carried out at our artificial ASSESS test site and observed with surface based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows studying soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the accurate determination of soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection and (ii) the feasibility of monitoring the dynamic shape of the capillary fringe reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.

scholarly journals Estimating field-scale soil water dynamics at a heterogeneous site using multi-channel GPR

2012 ◽  
Vol 9 (7) ◽  
pp. 8027-8062 ◽  
Author(s):  
X. Pan ◽  
J. Zhang ◽  
P. Huang ◽  
K. Roth
Keyword(s):  
Time Series ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Dynamics ◽  
Water Volume ◽  
Heavy Rainfall Event ◽  
Field Scale ◽  
Soil Water Dynamics ◽  
Layer Boundary

Abstract. We explore the feasibility to quantify the field-scale soil water dynamics through time series of GPR (ground-penetrating radar) measurements. They bridge the gap between accurate and well-established point measurements and the field-scale where soil hydrology issues are addressed. Working on a 40 m × 50 m area in a heterogeneous agricultural field, we obtain a time series of radargrams after a heavy rainfall event. On the one hand, these yield a three-dimensional representation of the subsurface architecture, in particular of the layer boundary that originates from paleo-sand dunes and of a number of clay inclusions in an otherwise rather uniform sand. On the other hand, the total soil water volume between the surface and the layer boundary is obtained. We assess the precision and the accuracy of these quantities and conclude that the method is sensitive enough to capture the spatial structure of the changing soil water content. While the sensitivity of the method still needs to be improved, it already produced useful information to understand the observed patterns in crop height and it yielded insight into the dynamics of soil water content at this site including the effect of evaporation.

scholarly journals Hydrotropic Root Behavior in Water-Saving Cultivation: A High-Resolution Monitoring Study of Soil Water Dynamics

2021 ◽  
Author(s):  
Qichen Li ◽  
Toshiaki Sugihara ◽  
Sakae Shibusawa ◽  
Minzan Li
Keyword(s):  
Soil Moisture ◽  
High Resolution ◽  
Water Content ◽  
Root System ◽  
Soil Water ◽  
Water Saving ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Soil Moisture Sensors ◽  
Wet Zone

Abstract BackgroundSubsurface irrigation has been confirmed to have high water use efficiency due to it irrigating only the crop root zone. Hydrotropism allows roots to grow towards higher water content areas for drought avoidance, which has research interests in recent years. However, most hydrotropism studies focused on a single root and were conducted in air or agar systems. The performance of hydrotropism in subsurface irrigation is not clear. ResultsWe developed a method to observe and analyze hydrotropism in soil under water-saving cultivation. A wet zone was produced around the whole root system based on using subsurface irrigation method and micro soil water dynamics were observed using high-resolution soil moisture sensors. This method enabled the observation and analysis of plant water absorption activities and the hydrotropic response of the root system. In the analysis, we first applied a high-pass filter and fast Fourier transform to the soil water dynamics data. The results indicated that the plant’s biological rhythm of photosynthetic activities can be identified from the soil moisture data. We then observed root growth in response to the dynamics of soil water content in the wet zone. We quantified root distribution inside and outside the wet zone and observed the shape of the root system from the cross-section of the wet zone. The results showed that the root hydrotropic response is not uniform for all roots of an individual plant. ConclusionsThis study verified the feasibility of using high-resolution soil moisture sensors to study root hydrotropic responses in soil during water-saving cultivation. To further evaluate a plant’s hydrotropic ability, it is necessary to use statistical analysis and/or a non-deterministic approach. Future studies may also explore developing an automated experimental system and robotic manipulations for getting steady repeatable observation of hydrotropism in water-saving cultivation.

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