Analyzing relationships among water uptake patterns, rootlet biomass distribution and soil water content profile in a subalpine shrubland using water isotopes

SUMMARYA field experiment was made to determine water uptake patterns of soya beans and water use and to compare relative effectiveness of roots at various depths in the profile.Depth of water extraction by the root systems increased with rooting depth. Water uptake rates decreased with soil water content at all soil depths and the soil water content at which roots extracted almost no water increased with depth. The maximum rate of uptake of the deep roots was greater, per unit of length, than shallow roots.

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Modelling the Impact on Root Water Uptake and Solute Return Flow of Different Drip Irrigation Regimes with Brackish Water

Water ◽

10.3390/w11030425 ◽

2019 ◽

Vol 11 (3) ◽

pp. 425 ◽

Cited By ~ 3

Author(s):

Fairouz Slama ◽

Nessrine Zemni ◽

Fethi Bouksila ◽

Roberto De Mascellis ◽

Rachida Bouhlila

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Brackish Water ◽

Deficit Irrigation ◽

Root Zone ◽

Root Water Uptake ◽

Return Flows ◽

Semi Arid

Water scarcity and quality degradation represent real threats to economic, social, and environmental development of arid and semi-arid regions. Drip irrigation associated to Deficit Irrigation (DI) has been investigated as a water saving technique. Yet its environmental impacts on soil and groundwater need to be gone into in depth especially when using brackish irrigation water. Soil water content and salinity were monitored in a fully drip irrigated potato plot with brackish water (4.45 dSm−1) in semi-arid Tunisia. The HYDRUS-1D model was used to investigate the effects of different irrigation regimes (deficit irrigation (T1R, 70% ETc), full irrigation (T2R, 100% ETc), and farmer’s schedule (T3R, 237% ETc) on root water uptake, root zone salinity, and solute return flows to groundwater. The simulated values of soil water content (θ) and electrical conductivity of soil solution (ECsw) were in good agreement with the observation values, as indicated by mean RMSE values (≤0.008 m3·m−3, and ≤0.28 dSm−1 for soil water content and ECsw respectively). The results of the different simulation treatments showed that relative yield accounted for 54%, 70%, and 85.5% of the potential maximal value when both water and solute stress were considered for deficit, full. and farmer’s irrigation, respectively. Root zone salinity was the lowest and root water uptake was the same with and without solute stress for the treatment corresponding to the farmer’s irrigation schedule (273% ETc). Solute return flows reaching the groundwater were the highest for T3R after two subsequent rainfall seasons. Beyond the water efficiency of DI with brackish water, long term studies need to focus on its impact on soil and groundwater salinization risks under changing climate conditions.

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Water drawdown by radish (Raphanus sativus L.) multiple-root systems evaluated using computed tomography

Soil Research ◽

10.1071/sr07116 ◽

2008 ◽

Vol 46 (3) ◽

pp. 228

Author(s):

M. A. Hamza ◽

S. H. Anderson ◽

L. A. G. Aylmore

Keyword(s):

Computed Tomography ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Root Zone ◽

Multiple Root ◽

Root Systems ◽

Bulk Soil ◽

Water Drawdown

Although measurements of water drawdown by single radish root systems have been previously published by the authors, further research is needed to evaluate water drawdown patterns in multiple-root systems. The objective of this study was to compare water transpiration patterns estimated using X-ray computed tomography (CT) with the traditional gravimetric method and to evaluate the effects of variably spaced multiple root systems on soil water content and corresponding water content gradients. Water drawdown showed a dual pattern in which it increased rapidly when soil water content was high at the beginning of transpiration, then slowed down to an almost constant level with time as water content decreased. These results contrast with the single-root system wherein transpiration rates initially increased rapidly and then slowly increased with time. Water uptake estimated using the CT method was observed to be 27–38% lower than the gravimetrically estimated water uptake; this difference was attributed to lower water uptake for the upper 30 mm layer (CT measured) than lower layers due to differences in root density. However, good correlation (r = 0.97) was found between both measurement methods. The drawdown patterns for multiple root systems showed a convex shape from the root surface to the bulk soil, compared with a nearly linear shape for single roots. The water content drawdown areas and the drawdown distances for multiple root systems were found to be much larger than those corresponding to single radish roots. Differential water content gradients were observed for roots spaced at 15-mm distances compared with 3–4-mm distances. These differential gradients from the bulk soil towards the root-zone occurred probably creating localised water potential gradients within the root-zone, which moved water from between roots to root surfaces. The lowest water content values were located in the inter-root areas. The CT-scanned layer probably acted as one drawdown area with particularly higher water drawdown from the inter-root areas.

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Estimation of root water uptake parameters by inverse modeling with soil water content data

Water Resources Research ◽

10.1029/2003wr002046 ◽

2003 ◽

Vol 39 (11) ◽

Cited By ~ 39

Author(s):

F. Hupet ◽

S. Lambot ◽

R. A. Feddes ◽

J. C. van Dam ◽

M. Vanclooster

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Inverse Modeling ◽

Root Water Uptake

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On the identification of macroscopic root water uptake parameters from soil water content observations

Water Resources Research ◽

10.1029/2002wr001556 ◽

2002 ◽

Vol 38 (12) ◽

pp. 36-1-36-14 ◽

Cited By ~ 39

Author(s):

F. Hupet ◽

S. Lambot ◽

M. Javaux ◽

M. Vanclooster

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Root Water Uptake

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Using measured soil water contents to estimate evapotranspiration and root water uptake profiles – a comparative study

Hydrology and Earth System Sciences ◽

10.5194/hess-19-409-2015 ◽

2015 ◽

Vol 19 (1) ◽

pp. 409-425 ◽

Cited By ~ 17

Author(s):

M. Guderle ◽

A. Hildebrandt

Keyword(s):

Time Series ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Root Water Uptake ◽

Performance Criteria ◽

Sensor Calibration ◽

Vertical Flow ◽

Sink Term

Abstract. Understanding the role of plants in soil water relations, and thus ecosystem functioning, requires information about root water uptake. We evaluated four different complex water balance methods to estimate sink term patterns and evapotranspiration directly from soil moisture measurements. We tested four methods. The first two take the difference between two measurement intervals as evapotranspiration, thus neglecting vertical flow. The third uses regression on the soil water content time series and differences between day and night to account for vertical flow. The fourth accounts for vertical flow using a numerical model and iteratively solves for the sink term. None of these methods requires any a priori information of root distribution parameters or evapotranspiration, which is an advantage compared to common root water uptake models. To test the methods, a synthetic experiment with numerical simulations for a grassland ecosystem was conducted. Additionally, the time series were perturbed to simulate common sensor errors, like those due to measurement precision and inaccurate sensor calibration. We tested each method for a range of measurement frequencies and applied performance criteria to evaluate the suitability of each method. In general, we show that methods accounting for vertical flow predict evapotranspiration and the sink term distribution more accurately than the simpler approaches. Under consideration of possible measurement uncertainties, the method based on regression and differentiating between day and night cycles leads to the best and most robust estimation of sink term patterns. It is thus an alternative to more complex inverse numerical methods. This study demonstrates that highly resolved (temporally and spatially) soil water content measurements may be used to estimate the sink term profiles when the appropriate approach is used.

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Time-lapse monitoring of root water uptake using electrical resistivity tomography and Mise-à-la-Masse: a vineyard infiltration experiment

10.5194/soil-2019-28 ◽

2019 ◽

Author(s):

Benjamin Mary ◽

Luca Peruzzo ◽

Jacopo Boaga ◽

Nicola Cenni ◽

Myriam Schmutz ◽

...

Keyword(s):

Electrical Resistivity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Electrical Resistivity Tomography ◽

Time Lapse ◽

Root Water Uptake ◽

Resistivity Tomography ◽

Infiltration Experiment

Abstract. This paper presents a time-lapse application of electrical methods (Electrical Resistivity Tomography – ERT – and Mise-à-la-Masse – MALM) for monitoring plant roots and their activity (root water uptake) during a controlled infiltration experiment. The use of non-invasive geophysical monitoring is of increasing interest as these techniques provide time-lapse imaging of processes that otherwise can only be measured at few specific spatial locations. The experiment here described was conducted in a vineyard in Bordeaux (France) and was focused on the behaviour of two neighbouring grapevines. The joint application of ERT and MALM has several advantages. While ERT in time-lapse mode is sensitive to changes in soil electrical resistivity and thus to the factors controlling it (mainly soil water content, in this context), MALM uses DC current injected in a tree stem to image where the plant-root system is in effective electrical contact with the soil at locations that are likely to be the same where root water uptake (RWU) takes place. Thus ERT and MALM provide complementary information about the root structure and activity. The experiment shows that the region of likely electrical current sources produced by MALM does not change significantly during the infiltration study time in spite of the strong changes of electrical resistivity caused by changes in soil water content. This fact, together with the evidence that current injection in the soil produces totally different patterns, corroborates the idea that this application of MALM highlights the active root density in the soil. When considering the electrical resistivity changes (as measured by ERT) inside the stationary volume of active roots delineated by MALM, the overall tendency is towards a resistivity increase, which can be linked to a decrease in soil water content caused by root water uptake. On the contrary, when considering the soil volume outside the MALM-derived root water uptake region, the electrical resistivity tends to decrease as an effect of soil water content increase caused by the infiltration. The results are particularly promising, and the method can be applied to a variety of scales including the laboratory scale where direct evidence of roots structure and root water uptake can help corroborate the approach. Once fully validated, the joint use of MALM and ERT can be used as a valuable tool to study the activity of roots under a wide variety of field conditions.

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Using measured soil water contents to estimate evapotranspiration and root water uptake profiles – a comparative study

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-11-10859-2014 ◽

2014 ◽

Vol 11 (9) ◽

pp. 10859-10902 ◽

Cited By ~ 1

Author(s):

M. Guderle ◽

A. Hildebrandt

Keyword(s):

Time Series ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Root Water Uptake ◽

Performance Criteria ◽

Sensor Calibration ◽

Vertical Flow ◽

Sink Term

Abstract. Understanding the role of plants for soil water relations, and thus for ecosystem functioning, requires information about root water uptake. We evaluated four different complex water balance methods to estimate sink term patterns and evapotranspiration directly from soil moisture measurements. We tested four methods: the first two take the difference between two measurement intervals as evapotranspiration, thus neglecting vertical flow. The third uses regression on the soil water content time series and differences between day and night to account for vertical flow. The fourth accounts for vertical flow using a numerical model and iteratively solves for the sink term. Neither of those methods requires any a priori information of root distribution parameters or evapotranspiration, which is the advantage, compared to common root water uptake models. To test the methods, a synthetic experiment with numerical simulations for a grassland ecosystem was conducted. Additionally, the time series were perturbed to simulate common sensor errors, like those due to measurement precision and inaccurate sensor calibration. We tested each method for a range of measurement frequencies and applied performance criteria to evaluate the suitability of each method. In general, we show that methods accounting for vertical flow predict evapotranspiration and the sink term distribution more accurately than the simpler approaches. Under consideration of possible measurement uncertainties, the method based on regression and differentiating between day and night cycles leads to the best and most robust estimation of sink term patterns. It is thus an alternative to more complex inverse numerical methods. This study demonstrates that highly resolved (temporal and spatial) soil water content measurements may be used to estimate the sink term profiles when the appropriate approach is used.

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Disentangling temporal and population variability in plant root water uptake from stable isotopic analysis: a labeling study

10.5194/hess-2019-543 ◽

2019 ◽

Author(s):

Valentin Couvreur ◽

Youri Rothfuss ◽

Félicien Meunier ◽

Thierry Bariac ◽

Philippe Biron ◽

...

Keyword(s):

Water Content ◽

Soil Water ◽

Physical Model ◽

Soil Water Content ◽

Water Uptake ◽

Temporal Dynamics ◽

Plant Root ◽

Root Water Uptake ◽

Leaf Water ◽

Stable Isotopic

Abstract. Isotopic labeling techniques have the potential to minimize the uncertainty of plant root water uptake (RWU) profiles estimated through multi-source (statistical) modeling, by artificially enhancing soil water isotopic gradient. Furthermore, physical models can account for hydrodynamic constraints to RWU if simultaneous soil and plant water status data is available. In this study, a population of tall fescue (Festuca arundinacae cv Soni) was grown in a macro-rhizotron setup under semi-controlled conditions to monitor such variables for a 34-hours long period following the oxygen stable isotopic (18O) labeling of deep soil water. Aboveground variables included tiller and leaf water oxygen isotopic compositions as well as leaf water potential (ψleaf), relative humidity, and transpiration rate. Belowground profiles of root length density (RLD), soil water content and isotopic composition were also sampled. While there were strong correlations between hydraulic variables as well as between isotopic variables, the experimental results underlined the discrepancy between variations of hydraulic and isotopic variables. In order to dissect the problem, we reproduced both types of observations with a one-dimensional physical model of water flow in the soil-plant domain, for 60 different realistic RLD profiles. While simulated ψleaf followed clear temporal variations with little differences across plants as if they were “on board of the same rollercoaster”, simulated δtiller values within the plant population were rather heterogeneous (“swarm-like”) with relatively little temporal variation and a strong sensitivity to rooting depth. The physical model thus suggested that the discrepancy between isotopic and hydraulic observations was logical, as the variability captured by the former was spatial and may not correlate with the temporal dynamics of the latter. For comparison purposes a Bayesian statistical model was also used to simulate RWU. While they predicted relatively similar cumulative RWU profiles, the physical model could differentiate spatial from temporal dynamics of the isotopic signature, and supported that the local increase of soil water content and formation of a peak of labelled water observed overnight were due to hydraulic lift.

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Effects of Arbuscular Mycorrhiza Fungi and Coffee Pulp Compost in Improving Soil Water Uptake by Chilli Around the Permanent Wilting Point Conditions

TERRA Journal of Land Restoration ◽

10.31186/terra.3.1.23-26 ◽

2020 ◽

Vol 3 (1) ◽

pp. 23-26

Author(s):

Ingri Dayana ◽

Bandi Hermawan ◽

Yudhi Harini Bertham ◽

Dwi Wahyuni Ganefianti

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Uptake ◽

Mycorrhizal Fungi ◽

Block Design ◽

Field Capacity ◽

Coffee Pulp ◽

Permanent Wilting Point ◽

Wilting Point

Soil water availability to the plants is a range of water content between the field capacity and the permanent wilting point (PWP) conditions. The PWP is defined as the lower limit of soil water content that the plant can extract water from the soil as indicated by the symptoms of wilting plants. This is because plant roots are unable to penetrate the soil micropores that contain the water. The study aims to analyze the effects of arbuscular mycorrhizal fungi (AMF) and compost in enhancing soil water absorption by the plant when the water content is close to the permanent wilting point. Four doses of AMF (0, 5, 10 and 15 g.plant-1) and three doses of coffee pulp-made compost (0, 5 and 10 ton.ha-1) were arranged according to a randomized complete block design with three replicates. Results showed that the application of AMF significantly enabled the plant to improve water uptake when the soil water content was about at the permanent wilting point conditions. The AMF addition of 15 g.plant-1 significantly prolonged the growing period of chili to wither and the plant showed the wilting symptoms at the soil water content of 5 to 7% lower than the no-AMF plants. Improved water uptake under water stress conditions was attributed to increases in the root colonization by AMF.

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