An exponential root-water-uptake model

1999 ◽  
Vol 79 (2) ◽  
pp. 333-343 ◽  
Author(s):  
K. Y. Li ◽  
J. B. Boisvert ◽  
R. De Jong
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Maximum Error ◽  
Root Water Uptake ◽  
Exponential Model ◽  
Rate Model ◽  
Loam Soil ◽  
Water Contents ◽  
Soil Water Contents

Macroscopic root-water-extraction models often do not adequately account for the non-uniform distribution of roots in the soil profile. We developed an exponential root-water-uptake model, which was derived from a measured root density distribution function. The model, incorporated in the Soil-Water-Atmosphere-Plant (SWAP) simulation model, was tested on a clay loam soil cropped to soybeans and on a sandy loam soil cropped to corn, near Ottawa. Comparisons of measured and simulated soil water contents with the exponential model, a linear depth-dependent model and a constant-extraction-rate model were also made. The exponential model performed satisfactorily (average relative errors <20%) when used to simulate measured field soil water contents at various depths. The constant-extraction-rate model overestimated the soil water contents in the upper part of the soil profile (maximum error 0.24 cm3 cm−3) and underestimated them (maximum error −0.09 cm3 cm−3) in the lower part. The exponential model and the linear model performed fairly similarly at the lower depths, but the exponential model gave better results in the near-surface horizons. The exponential model was sensitive to the root distribution coefficient and to the rooting depth, when the latter was approximately less than 40 cm. The results of this study suggest that the exponential root-water-uptake model as incorporated in SWAP is an improvement over those models, which do not account for the root distribution in the soil. Key words: SWAP, soil water simulation, root distribution, corn, soybeans, sensitivity analysis

Measurements and simulation of leaf xylem water potential and root water uptake in heterogeneous soil water contents

2019 ◽  
Vol 124 ◽  
pp. 96-105 ◽  
Author(s):  
Faisal Hayat ◽  
Mutez Ali Ahmed ◽  
Mohsen Zarebanadkouki ◽  
Gaochao Cai ◽  
Andrea Carminati
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Xylem Water Potential ◽  
Heterogeneous Soil ◽  
Water Contents ◽  
Soil Water Contents

Corrigendum to ‘‘Measurements and simulation of leaf xylem water potential and root water uptake in heterogeneous soil water contents’’

2020 ◽  
Vol 138 ◽  
pp. 103566
Author(s):  
Faisal Hayat ◽  
Mutez Ali Ahmed ◽  
Mohsen Zarebanadkouki ◽  
Gaochao Cai ◽  
Andrea Carminati
Keyword(s):  
Water Resources ◽  
Water Potential ◽  
Soil Water ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Xylem Water Potential ◽  
Heterogeneous Soil ◽  
Water Contents ◽  
Soil Water Contents

A method for identifying optimum strategies of measuring soil water contents for calibrating a root water uptake model

2000 ◽  
Vol 227 (1-4) ◽  
pp. 273-286 ◽  
Author(s):  
P.A.D. Musters ◽  
W. Bouten
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Water Contents ◽  
Soil Water Contents

Towards the consideration of soil-root resistances in root water uptake models with macroscopic representations of hydraulic root architecture

2021 ◽  
Author(s):  
Jan Vanderborght ◽  
Valentin Couvreur ◽  
Felicien Meunier ◽  
Andrea Schnepf ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Root System ◽  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Root Architecture ◽  
Soil Layer ◽  
Root Water Uptake ◽  
Hydraulic Architecture ◽  
Root Segments ◽  
Soil Volume

&lt;p&gt;Plant water uptake from soil is an important component of terrestrial water cycle with strong links to the carbon cycle and the land surface energy budget. To simulate the relation between soil water content, root distribution, and root water uptake, models should represent the hydraulics of the soil-root system and describe the flow from the soil towards root segments and within the 3D root system architecture according to hydraulic principles. We have recently demonstrated how macroscopic relations that describe the lumped water uptake by all root segments in a certain soil volume, e.g. in a thin horizontal soil layer in which soil water potentials are uniform, can be derived from the hydraulic properties of the 3D root architecture. The flow equations within the root system can be scaled up exactly and the total root water uptake from a soil volume depends on only two macroscopic characteristics of the root system: the root system conductance, K&lt;sub&gt;rs&lt;/sub&gt;, and the uptake distribution from the soil when soil water potentials in the soil are uniform, &lt;strong&gt;SUF&lt;/strong&gt;. When a simple root hydraulic architecture was assumed, these two characteristics were sufficient to describe root water uptake from profiles with a non-uniform water distribution. This simplification gave accurate results when root characteristics were calculated directly from the root hydraulic architecture. In a next step, we investigate how the resistance to flow in the soil surrounding the root can be considered in a macroscopic root water uptake model. We specifically investigate whether the macroscopic representation of the flow in the root architecture, which predicts an effective xylem water potential at a certain soil depth, can be coupled with a model that describes the transfer from the soil to the root using a simplified representation of the root distribution in a certain soil layer, i.e. assuming a uniform root distribution.&lt;/p&gt;

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)

scholarly journals How to put plant root uptake into a soil water flow model

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 43
Author(s):  
Xuejun Dong
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Plant Root ◽  
Root Water Uptake ◽  
Root Uptake ◽  
Water Dynamics ◽  
Rooting Depth ◽  
Plant Root Uptake

The need for improved crop water use efficiency calls for flexible modeling platforms to implement new ideas in plant root uptake and its regulation mechanisms. This paper documents the details of modifying a soil infiltration and redistribution model to include (a) dynamic root growth, (b) non-uniform root distribution and water uptake, (c) the effect of water stress on plant water uptake, and (d) soil evaporation. The paper also demonstrates strategies of using the modified model to simulate soil water dynamics and plant transpiration considering different sensitivity of plants to soil dryness and different mechanisms of root water uptake. In particular, the flexibility of simulating various degrees of compensated uptake (whereby plants tend to maintain potential transpiration under mild water stress) is emphasized. The paper also describes how to estimate unknown root distribution and rooting depth parameters by the use of a simulation-based searching method. The full documentation of the computer code will allow further applications and new development.

Root water uptake and profile soil water as affected by vertical root distribution

Plant Ecology ◽  
2006 ◽  
Vol 189 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Gui-Rui Yu ◽  
Jie Zhuang ◽  
Keiichi Nakayama ◽  
Yan Jin
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Root Water Uptake ◽  
Vertical Root Distribution

Tree/pasture interactions at a range of tree densities in an agroforestry experiment. II. Water uptake in relation to rooting patterns

1990 ◽  
Vol 41 (4) ◽  
pp. 697 ◽  
Author(s):  
J Eastham ◽  
CW Rose ◽  
DM Cameron ◽  
SJ Rance ◽  
T Talsma ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Unit Root ◽  
Evaporation Rate ◽  
Surface Soil ◽  
Tree Density ◽  
Soil Horizons ◽  
Rooting Patterns ◽  
Water Contents ◽  
Soil Water Contents

Patterns of water uptake throughout a drying period of approximately one year were investigated under trees and pasture at three tree densities in an agroforestry experiment, and related to tree and pasture rooting patterns and water use. A greater proportion of soil water was extracted from deep in the soil profile under the densely planted trees, owing to lower soil water contents in upper horizons and deeper and more dense rooting systems than at lower tree densities. As the drought period progressed, the ratios of tree transpiration rate and pasture evaporation rate to equilibrium evaporation rate tended to decrease at each tree density as soil water contents in upper horizons decreased, and an increasing proportion of water was extracted from deeper soil horizons. At each tree density, the rate of water uptake per unit root length was lowest in surface soil horizons and tended to increase with increasing soil depth. The rate of water uptake per unit root length tended to increase with time in deeper, wetter soil horizons and decrease with time in surface soil horizons as soil water content decreased.

scholarly journals The Effect of Irrigation Rate on the Water Relations of Young Citrus Trees in High-Density Planting

2021 ◽  
Vol 13 (4) ◽  
pp. 1759
Author(s):  
Said A. Hamido ◽  
Kelly T. Morgan
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Salinity ◽  
Planting Density ◽  
Stem Water Potential ◽  
Irrigation Rate ◽  
Biological Stress ◽  
Stem Water ◽  
Water Contents ◽  
Soil Water Contents

The availability and proper irrigation scheduling of water are some of the most significant limitations on citrus production in Florida. The proper volume of citrus water demand is vital in evaluating sustainable irrigation approaches. The current study aims to determine the amount of irrigation required to grow citrus trees at higher planting densities without detrimental impacts on trees’ water relation parameters. The study was conducted between November 2017 and September 2020 on young sweet orange (Citrus sinensis) trees budded on the ‘US-897’ (Cleopatra mandarin x Flying Dragon trifoliate orange) citrus rootstock transplanted in sandy soil at the Southwest Florida Research and Education Center (SWFREC) demonstration grove, near Immokalee, Florida. The experiment contained six planting densities, including 447, 598, and 745 trees per ha replicated four times, and 512, 717, and 897 trees per ha replicated six times. Each density treatment was irrigated at 62% or 100% during the first 15 months between 2017 and 2019 or one of the four irrigation rates (26.5, 40.5, 53, or 81%) based on the calculated crop water supplied (ETc) during the last 17 months of 2019–2020. Tree water relations, including soil moisture, stem water potential, and water supplied, were collected periodically. In addition, soil salinity was determined. During the first year (2018), a higher irrigation rate (100% ETc) represented higher soil water contents; however, the soil water content for the lower irrigation rate (62% ETc) did not represent biological stress. One emitter per tree regardless of planting density supported stem water potential (Ψstem) values between −0.80 and −0.79 MPa for lower and full irrigation rates, respectively. However, when treatments were adjusted from April 2019 through September 2020, the results substantially changed. The higher irrigation rate (81% ETc) represented higher soil water contents during the remainder of the study, the lower irrigation rate (26.5% ETc) represents biological stress as a result of stem water potential (Ψstem) values between −1.05 and −0.91 MPa for lower and higher irrigation rates, respectively. Besides this, increasing the irrigation rate from 26.5% to 81%ETc decreased the soil salinity by 33%. Although increasing the planting density from 717 to 897 trees per hectare reduced the water supplied on average by 37% when one irrigation emitter was used to irrigate two trees instead of one, applying an 81% ETc irrigation rate in citrus is more efficient and could be managed in commercial groves.

scholarly journals Analysis of Soil Water Response to Grass Transpiration

2013 ◽  
Vol 1 (No. 3) ◽  
pp. 85-98
Author(s):  
Dohnal Michal ◽  
Dušek Jaromír ◽  
Vogel Tomáš ◽  
Herza Jiří
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Preferential Flow ◽  
Water Movement ◽  
Control Volume ◽  
Water Pressure ◽  
Lower Boundary ◽  
Root Water Uptake ◽  
Water Dynamics ◽  
Soil Water Dynamics

This paper focuses on numerical modelling of soil water movement in response to the root water uptake that is driven by transpiration. The flow of water in a lysimeter, installed at a grass covered hillslope site in a small headwater catchment, is analysed by means of numerical simulation. The lysimeter system provides a well defined control volume with boundary fluxes measured and soil water pressure continuously monitored. The evapotranspiration intensity is estimated by the Penman-Monteith method and compared with the measured lysimeter soil water loss and the simulated root water uptake. Variably saturated flow of water in the lysimeter is simulated using one-dimensional dual-permeability model based on the numerical solution of the Richards&rsquo; equation. The availability of water for the root water uptake is determined by the evaluation of the plant water stress function, integrated in the soil water flow model. Different lower boundary conditions are tested to compare the soil water dynamics inside and outside the lysimeter. Special attention is paid to the possible influence of the preferential flow effects on the lysimeter soil water balance. The adopted modelling approach provides a useful and flexible framework for numerical analysis of soil water dynamics in response to the plant transpiration.

Sign in / Sign up

Export Citation Format

Share Document