scholarly journals Root distributions in a laboratory box evaluated using two different techniques (gravimetric and image processing) and their impact on root water uptake simulated with HYDRUS

2016 ◽  
Vol 64 (2) ◽  
pp. 196-208 ◽  
Author(s):  
Aleš Klement ◽  
Miroslav Fér ◽  
Šárka Novotná ◽  
Antonín Nikodem ◽  
Radka Kodešová
Keyword(s):  
Image Analysis ◽  
Water Uptake ◽  
Fine Roots ◽  
Root Zone ◽  
Root Water Uptake ◽  
Root Density ◽  
Gravimetric Analysis ◽  
Lower Root ◽  
The Impact ◽  
Hydrus 1D

Abstract Knowledge of the distribution of plant roots in a soil profile (i.e. root density) is needed when simulating root water uptake from soil. Therefore, this study focused on evaluating barley and wheat root densities in a sand-vermiculite substrate. Barley and wheat were planted in a flat laboratory box under greenhouse conditions. The box was always divided into two parts, where a single plant row and rows cross section (respectively) was simulated. Roots were excavated at the end of the experiment and root densities were assessed using root zone image processing and by weighing. For this purpose, the entire area (width of 40 and height of 50 cm) of each scenario was divided into 80 segments (area of 5×5 cm). Root density in each segment was expressed as a root percentage of the entire root cluster. Vertical root distributions (i.e. root density with respect to depth) were also calculated as a sum of root densities in each 5 cm layer. Resulting vertical root densities, measured evaporation from the water table (used as the potential root water uptake), and the Feddes stress response function model were used for simulating substrate water regime and actual root water uptake for all scenarios using HYDRUS-1D. All scenarios were also simulated using HYDRUS-2D. One scenario (areal root density of barley sown in a single row, obtained using image analysis) is presented in this paper (because most scenarios showed root water uptakes similar to results of 1D scenarios). The application of two root detecting techniques resulted in noticeably different root density distributions. Differences were mainly attributed to the fact that fine roots of high density (located mostly at the deeper part of the box) had lower weights in comparison to the weight of few large roots (at the box top). Thus, at the deeper part, higher root density (with respect to the entire root zone) was obtained using the image analysis in comparison to that from the gravimetric analysis. Conversely, lower root density was obtained using the image analysis at the upper part in comparison to that from the gravimetric analysis. On the other hand, fine roots overlapped each other and therefore were not visible in the image, which resulted in lower root density values from image analysis. Root water uptakes simulated with HYDRUS-1D using diverse root densities obtained for each cereal declined differently from the potential root water uptake values depending on water scarcity at depths of higher root density. Usually, an earlier downtrend associated with gradual root water up-take decreases and vice versa. Similar root water uptakes were simulated for the presented scenario using the HYDRUS-1D and HYDRUS-2D models. The impact of the horizontal root density distribution on root water uptake was, in this case, less important than the impact of the vertical root distribution resulting from different techniques and sowing scenarios.

Simulation of soil water dynamics in structured heavy soils with respect to root water uptake

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
David Zumr ◽  
Michal Dohnal ◽  
Miroslav Hrnčíř ◽  
Milena Císlerová ◽  
Tomáš Vogel ◽  
...  
Keyword(s):  
Water Uptake ◽  
Nitrogen Fertilization ◽  
Drip Irrigation ◽  
Soil Profile ◽  
Water Regime ◽  
Root Zone ◽  
Root Water Uptake ◽  
Water Dynamics ◽  
Preferential Pathways ◽  
The Impact

AbstractIn agricultural lands has the soil moisture uptake from the root system a significant effect on the water regime of the soil profile. In texturally heavy soils, where preferential pathways are present, infiltrated precipitation and irrigation water with diluted fertilizers quickly penetrate to a significant depth and often reach an under-root zone or even the ground-water level. Such a scenario is likely to happen during long summer periods without rain followed by heavy precipitation events, when a part of the water may flow through desiccated cracks.Since 2001 the effects of drip irrigation and nitrogen fertilization of potatoes (Solanum tuberosum L., cultivar Agria) have been monitored within the frame of a research project at the experimental site Valecov (Czech Republic). Based upon the measured data an attempt has been made to simulate the water regime of the soil profile at a selected experimental plot, considering the impact of preferential flow and root water uptake. The dual-permeability simulation model S_1D_Dual (VOGEL et al., 2000) was used for the simulation. The soil hydraulic parameters were inversely determined using Levenberg-Marquardt method. Measured and simulated pressure heads were utilized in the optimization criterion. The scaling approach was applied to simplify the description of the spatial variability of the soil profile.The results of simulations demonstrate that during particular rainfall events the water reaches significant depths of the soil profile via preferential pathways. The effect of the root zone is dominant during dry periods, when capillary water uptake from the layers below roots becomes important. This should be taken in account into the optimization of the drip irrigation and nitrogen fertilization schedule.

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

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 425 ◽  
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.

scholarly journals Water and salt transport in daily irrigated root zone.

1987 ◽  
Vol 35 (3) ◽  
pp. 395-406
Author(s):  
C. Dirksen
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Gamma Ray ◽  
Root Zone ◽  
Root Water Uptake ◽  
Salt Transport ◽  
Soil Water Retention ◽  
Transport Models ◽  
Leaching Fraction ◽  
Water Contents

With closed, high-frequency irrigation systems, the water supply can be tailored to the instant needs of plants. To be able to do this optimally, it is necessary to understand how plants interact with their environment. To study water uptake under a variety of non-uniform conditions in the root zone, lucerne was grown in laboratory soil columns with automated gamma ray attenuation, tensiometer and salinity sensor equipment to measure soil water contents, pressure potentials and osmotic potentials, respectively. The columns were irrigated with water of different salinity at various frequencies and leaching fractions. This paper presents results obtained in a column irrigated daily with water of conductivity 0.33 S/m (h0 = -13.2 m) at a target leaching fraction of 0.08. This includes the drying and wetting patterns under daily irrigations in deficit and excess of evapotranspiration, respectively. After 230 days the salination of the column had still not reached a steady state. Salinity increased rapidly with depth and root water uptake was shallow for the deep-rooting lucerne. Water and salt transport under daily irrigation cannot be described without taking hysteresis of soil water retention into account. The data presented are suitable for testing various water uptake models, once numerical water and salt transport models of the required complexity are operational. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Sensitivity and uncertainty analysis of the HYDRUS-1D model for root water uptake in saline soils

2018 ◽  
Vol 69 (2) ◽  
pp. 163 ◽  
Author(s):  
Wenzhi Zeng ◽  
Guoqing Lei ◽  
Yuanyuan Zha ◽  
Yuanhao Fang ◽  
Jingwei Wu ◽  
...  
Keyword(s):  
Salt Stress ◽  
Water Uptake ◽  
Soil Salinity ◽  
Root Water Uptake ◽  
Stress Factors ◽  
Saline Soils ◽  
Growth Stages ◽  
1D Model ◽  
Maximum Root ◽  
Hydrus 1D

A variance-based global sensitivity analysis (extended Fourier amplitude sensitivity test, EFAST) was applied to the Feddes module of the HYDRUS-1D model, and the sensitivity indices including both main and total effects of actual root water uptake (RWUa) to seven Feddes parameters were quantified at different growth stages of sunflower (Helianthus annuus L.): seedling, bud, flowering and maturity. The effects of soil salinity, climate conditions, and crop root growth on parameter sensitivity were explored by analysing three precipitation frequencies and two maximum root depths across four field locations with different soil salinity levels in China’s sunflower-growing regions. Uncertainties for RWUa were evaluated at four stages with varying Feddes parameters for different field locations, precipitation frequencies and maximum root depths. We found that the water stress factor concerning ceasing root water uptake (h4), and two salt stress factors ht and Sp, indicating the salinity threshold and the slope of the curve determining the fractional decline in root water uptake per unit increase in salinity below the threshold, respectively, were three most important Feddes parameters for RWUa estimation in HYDRUS-1D. In addition, the effects of soil salinity and precipitation frequencies were stronger than maximum root depth on the order of the parameters’ impacts on RWUa. Our study suggested that h1, h2, h3h, and h3l might be determined by an economical method (e.g. literature review) in saline soils with limited observations, but it is better to calibrate wilting point (h4) and salt stress parameters (ht and Sp) based on local measurements.

scholarly journals Estimating the Root Water Uptake of Surface-Irrigated Apples Using Water Stable Isotopes and the Hydrus-1D Model

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1624 ◽  
Author(s):  
Lijian Zheng ◽  
Juanjuan Ma ◽  
Xihuan Sun ◽  
Xianghong Guo ◽  
Qiyun Cheng ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Water Use Efficiency ◽  
Water Use ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Surface Irrigation ◽  
Apple Trees ◽  
1D Model ◽  
Use Efficiency ◽  
Hydrus 1D

The future production of irrigated fruit orchards in the Loess Plateau of China is threatened by a shortage of freshwater. To improve water use efficiency under conditions where irrigation is limited, it is necessary to quantify the root water uptake (RWU) of apple trees. The RWU of apple trees was estimated under surface irrigation using water stable isotope technology and the Hydrus-1D model. Using the Romero-Saltos and IsoSource models, the stable isotopes of water in stems, different soil depths, and different precipitation were analyzed in a 5-year-old dwarfing apple orchard during two seasons 2016 and 2017. Hydrus-1D model was able to simulate the RWU of apple using the maximum coefficient of determination (0.9), providing a root mean square error of 0.019 cm3 cm−3 and a relative error of 2.25%. The results showed that the main depth of RWU ranged from 0–60 cm during the growth season, with the main contribution occurring in the 0–40 cm depth. These findings indicated that reducing the traditional surface irrigation depth will be important for improving the irrigation water use efficiency.

scholarly journals Modeling the Impact of Biopores on Root Growth and Root Water Uptake

2019 ◽  
Vol 18 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Magdalena Landl ◽  
Andrea Schnepf ◽  
Daniel Uteau ◽  
Stephan Peth ◽  
Miriam Athmann ◽  
...  
Keyword(s):  
Root Growth ◽  
Water Uptake ◽  
Root Water Uptake ◽  
The Impact

Root length density and water uptake in cereals and grain legumes: how well are they correlated

1987 ◽  
Vol 38 (3) ◽  
pp. 513 ◽  
Author(s):  
AP Hamblin ◽  
D Tennant
Keyword(s):  
Water Uptake ◽  
Root Length ◽  
Root Zone ◽  
Root Length Density ◽  
Genotypic Variation ◽  
Root Water Uptake ◽  
Grain Legumes ◽  
Rooting Depth ◽  
Rates Of Change ◽  
Axial Resistance

Total root length per unit ground area (La) is often considered to be directly related to the amount and rate of water uptake. Experiments were conducted to compare the water use of spring wheat, barley, lupin (L. angustifolius) and field pea on four differing soil types in drought-stressed conditions. The La values of cereals were consistently five to ten times as large as those of grain legumes, whereas the aboveground biomass was sim~iar and never greater than twice that of the grain legumes. Growing-season water loss (WL) from the soil profile was very similar for wheat and lupins, despite this big difference in root length. Soil evaporation may have been greater under lupins, but when crop water uptake was compared for the period when leaf area was greatest, rates of change in soil water content within the root zone were still similar and were not well correlated with La. Specific root water uptake (Ur) was consistently greater for lupin than wheat. Maximum rooting depth was better correlated with WL than was La in all cases. Higher Ur values in lupin and pea may be related to their large and abundant metaxylem vessels, which give much lower axial resistance than in cereals. These results provide strong evidence for genotypic variation in root morphology, density and root extension between dicotyledenous and monocotyledenous species. They also indicate that La is not necessarily the root morphological characteristic most responsible for efficiency of water uptake in drought-stressed environments.

Seawater intrusion dynamic at the Casetta farmland (Venice). Characterization using HYDRUS-1D

2020 ◽  
Author(s):  
Greta Finco ◽  
Ester Zancanaro ◽  
Pietro Teatini ◽  
Francesco Morari
Keyword(s):  
Electrical Conductivity ◽  
Solute Transport ◽  
Water Table ◽  
Water Uptake ◽  
Seawater Intrusion ◽  
Root Water Uptake ◽  
Variable Boundary ◽  
Soil Hydraulic ◽  
Hydrus 1D ◽  
Monitoring Stations

<p>Soil and groundwater salinization due to seawater intrusion is among the most important problems in coastal farmlands. Inverse estimation of unsaturated soil hydraulic and solute transport properties represents a fundamental step to understand saltwater intrusion dynamics. A three-year study was conducted in a maize field bounding the southern Venice Lagoon. Volumetric water content θ, soil matric potential ψ, and apparent electrical conductivity (ECa) were monitored hourly by five automatic monitoring stations at four depths (0.1, 0.3, 0.5 and 0.7 m). Groundwater electrical conductivity (EC) and depth to the water table were measured in five wells. In addition, soil water and groundwater samples were collected and analyzed to determine the chemical composition. Soil hydraulic parameters for the van Genuchten-Mualen equations were determined using the inverse method in Hydrus-1D. The water flow was modelled based on the daily averages of θ at the four depths and the θ values measured in the lab at selected ψ on undisturbed soil cores extracted from the five monitoring stations. Precipitation, crop transpiration, soil evaporation and depth to the water table were used as time-variable boundary conditions. Root water uptake was estimated by using Feddes model. Finally, the major ion chemistry module of HYDRUS-1D was used to model solute transport and root water uptake reduction due to osmotic stress. The use of HYDRUS-1D to understand saltwater dynamics would enable the developing of mitigation strategies to limit its detrimental effect on farmland productivity and groundwater quality.</p>

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