Determination of withdrawal of water from soil by crop roots as a function of depth and time

Rose, C. M.; Stern, WR

doi:10.1071/sr9670011

Cited by 80 publications

(41 citation statements)

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“…This sorption by the roots are given in Figure 3. Although the root absorption rate (r.) was greatest near the 75-cm depth, the maximal value of 3.5 X 10' day-' was quite low when compared with values reported for well watered soils (21,30). Since the soil matric potential at 75 cm was about -0.2 bars, the low extraction rate also suggests low root density or high root impedance to water transport at this depth.…”

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confidence: 83%

Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton

1971

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Diurnal variations in leaf water potential, diffusion resist.ance, relative water content, stem diameter, leaf temperature, and energy balance components were measured in cotton (Gossypium hirsutum L. var. Lankart 57) during drought stress under field conditions. A plot of leaf water potential against either relative water content or stem diameter during the 24-hour period yielded a closed hysteresis loop. The relation between ceil hydration and evaporation is discussed.Despite low soil water potential in the main root zone, significant plant evaporation rates were maintained. Root absorption rates as a function of soil depth were calculated from water content profiles measured with a neutron probe.The maximal root absorption rate of 3.5 X 10-' day-' occurred at the 75-centimeter depth, welil below the main root zone.Stomatal resistance of individual leaves during the daylight hours remained nearly constant at 2.5 seconds centimetereven though leaf water potentials approached -30 bars. A growth chamber study indicated stomatal closure occurred at potentials near -16 bars. Possible implications of high soil water stress in relation to stomatal funetion and growth are discussed. Based on an energy balance method, the actual to potential plant evapotranspiration ratio was 0.43 for the 24-hour period, indicating partial stomatal closure. A surface resistance, r,, of 4.0 seconds centimeter-' was calculated for the incomplete canopy with the use of the energy balance data. Alternatively, a canopy resistance of 1.3 seconds centimeter-' was attained from a relationship between leaf area and stomatal resistance of individual leaves. If the soil resistance was assumed to be very large and the canopy resistance was weighted for the fractional ground cover of the crop, the calculated surface resistance was 4.3 seconds centimeter-. Under these conditions, the two independent estimates of r, were in essential agreement.Significant enhancement of our understanding of the response of internal plant water status to changes in the evaporative demand, in the water potential in the root environment, and in illumination have been made by theoretical analysis and by experiments under controlled conditions, but parallel studies with plants growing in a natural environment are relatively rare. Because of a prolonged drought in central Texas, the 1969 summer growing season provided an opportunity for field study of the water status of cotton under high soil water stress. Accordingly, diurnal variations in plant and soil water status and evaporation rate during drought stress were measured for purposes of comparison with theoretical predictions and with results from experiments under controlled conditions.Field studies by Weatherley (32) and Slatyer (23) have shown that plant water status is directly influenced by evaporative demand until a critical soil water potential is reached. The transpiration rates presented in these studies were inferred from a technique with the use of excised leaves and cannot be interpreted in absolute...

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confidence: 83%

Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton

1971

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“…Gardner (1983) relacionou a distribuição radicular de sorgo medida com a estimada por modelo matemático e, já nesse trabalho, comentava sobre a dificuldade em obter uma boa estimativa da distribuição radicular a partir de amostras de solo. Rose & Stern (1967) fizeram uma análise completa e detalhada do consumo de água no solo pelas raízes de uma cultura. A aplicação do método proposto por esses autores é difícil, considerando a necessidade de uma caracterização físico-hídrica detalhada do perfil do solo.…”

Section: Introductionunclassified

“…O método do balanço de água num volume de controle de solo tem sido apresentado por vários autores (Rose, 1966;Slatyer, 1967;Rose & Stern, 1967;Barrada, 1971;Reichardt et al, 1979, Guandique & Libardi, 1997Cintra et al, 2000), sendo seus componentes (precipitação, irrigação, evapotranspiração, deflúvio superficial, drenagem, ascensão capilar e variação da armazenagem de água no solo) apresentados numa forma integrada ou diferenciada numa equação geral de balanço de massa. Atualmente, a ênfase destes balanços tem sido dada à disponibilidade de água no solo relacionada com elementos climáticos e desenvolvimento vegetal.…”

Section: Introductionunclassified

Balanço de água no volume de solo explorado pelo sistema radicular de uma planta de citros

Cruz

Libardi²,

Carvalho³

et al. 2005

Rev. Bras. Ciênc. Solo

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RESUMOA produtividade das culturas agrícolas, associada às condições climáticas e edáficas, depende da disponibilidade de água e nutrientes no solo em época e quantidades apropriadas. A falta ou excesso de água no solo são fatores limitantes ao crescimento vegetal e podem diminuir a produtividade. Portanto, estudos que levem a um melhor entendimento de como a água se comporta na zona radicular de uma cultura agrícola no campo são de importância indiscutível ao adequado manejo agrícola. O objetivo do presente trabalho foi avaliar o método do balanço de água no solo aplicado ao volume de solo explorado pelo sistema radicular de uma planta de citros, considerando cinco profundidades de solo e cinco distâncias horizontais do tronco em duas direções a partir do tronco (uma ao longo e outra perpendicular à linha de plantas) e, então, verificar a contribuição de cada uma das camadas de solo avaliadas à evapotranspiração real da planta. O experimento foi realizado num Latossolo Vermelho-Amarelo distrófico argissólico em um pomar de citros, no município de Piracicaba (SP), durante dois períodos, um seco (40 dias) e um chuvoso (37 dias). Para atender ao objetivo proposto, um conjunto de 25 tensiômetros (cinco profundidades x cinco distâncias do tronco) foi instalado ao longo da linha e um outro, idêntico, perpendicular à linha, em direção à entrelinha. A armazenagem foi calculada a partir das leituras dos dois conjuntos de 25 tensiômetros cujos potenciais mátricos determinados foram convertidos em umidades volumétricas pelas

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“…The water flow through the roots q Root at each depth was calculated as the difference between total vertical flow and capillary flow (Rijtema, 1965;Rose and Stern, 1967;Feddes, 1971;Ehlers, 1975;Strebel et al, 1975): (Allen et al 1994) for a lysimeter with constant water level of 40 cm (3 and 7 days monitoring intervals) Table 5. Water balance components for a monitoring period of four weeks ET Grass = Grass reference Evapotranspiration after Allen et al, 1994 Period 15-21.7 22-28.7 29.7-5.8.…”

Section: Evapotranspirationmentioning

confidence: 99%

An easily installable groundwater lysimeter to determine waterbalance components and hydraulic properties of peat soils

Schwaerzel

Bohl

2003

Hydrol. Earth Syst. Sci.

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A simple method for the installation of groundwater lysimeters in peat soils was developed which reduces both time and financial effort significantly. The method was applied on several sites in the Rhinluch, a fen peat land 60 km northwest of Berlin, Germany. Over a two-year period, upward capillary flow and evapotranspiration rates under grassland with different groundwater levels were measured. The installation of tensiometers and TDR probes additionally allowed the in situ determination of the soil hydraulic properties (water retention and unsaturated hydraulic conductivity). The results of the measurements of the unsaturated hydraulic conductivity demonstrate that more than one single method has to be applied if the whole range of the conductivity function from saturation to highly unsaturated is to be covered. Measuring the unsaturated conductivity can be done only in the lab for an adequately wide range of soil moisture conditions.

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Determination of withdrawal of water from soil by crop roots as a function of depth and time

Cited by 80 publications

References 0 publications

Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton

Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton

Balanço de água no volume de solo explorado pelo sistema radicular de uma planta de citros

An easily installable groundwater lysimeter to determine waterbalance components and hydraulic properties of peat soils

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