Young lime tree evapotranspiration measurements in lysimeters with automated irrigation

Author(s):  
Ana belén Mira-García ◽  
Juan Vera ◽  
Wenceslao Conejero ◽  
Mª Carmen Ruiz-Sánchez

<p>Lime tree growing area is increasing in Mediterranean temperate regions. In these areas, climate change scenario is expected to raise air temperature and water shortages. Such scenario requires new approaches to implement a precision irrigation in agriculture. In order to use water more efficiently, it becomes necessary to accurately determining the crop water needs, which are estimated by crop evapotranspiration computations (ETc). In this study the ETc of young lime trees grown under Mediterranean conditions were determined using the soil water balance method. For this purpose, two-year old lime trees (Citrus latifolia Tan., cv. Bearss) grafted on C. macrophylla rootstock were cultivated in pot-lysimeters, equipped with capacitance and granular matric sensors for real-time monitoring of the soil water status. Irrigation, drainage, and pot weight were also monitored continuously. All measurements were integrated into a telemetry platform. Agro-meteorological variables, plant water status (stem (Ψ<sub>stem</sub>) and leaf (Ψ<sub>leaf</sub>) water potentials), and leaf gas exchange parameters (stomatal conductance (g<sub>s</sub>) and net photosynthesis (P<sub>n</sub>)) were measured. Along the experiment, an automated irrigation protocol based on volumetric soil water content (θ<sub>v</sub>) threshold values were programmed, guaranteeing an adequate lime tree water status. Irrigation dose was calculated based on a feed-back strategy maintaining θ<sub>v </sub>within 30% management allowed depletion.</p><p>During the experimental period, the lime trees were well irrigated as revealed midday Ψ<sub>stem </sub>values that were maintained above -0.8 MPa. Also, the mean seasonal values of ≈ 7 µmol m<sup>−2</sup> s<sup>−1</sup> and 80 mmol m<sup>−2</sup> s<sup>−1</sup>, for P<sub>n</sub> and g<sub>s</sub>, respectively, indicated optimal gas exchange values. The computed water balance parameters yielded values for the crop evapotranspiration from 0.25<sup></sup>to 2.56 mm day<sup>-1</sup>, in winter and summer months, respectively, with maximum values in July when evaporative demand conditions were the highest. This soil water balance was daily validated by the pot weight balance through the year.</p><p>In conclusion, the automated irrigation of young potted lime trees, using soil water content as a control system variable, has ensured an adequate lime tree water status. A simple, robust weighing/drainage lysimeter, with real-time monitoring of the soil water balance parameters, has been proved practical and economical tool for crop evapotranspiration measurements.</p><p>Acknowledgments: This work was funded by Spanish Agencia Estatal de Investigación (PID2019-106226RB-C2-1/AEI/10.13039/501100011033) and Fundación Séneca, Región de Murcia (19903/GERM/15) projects.</p>

2018 ◽  
Vol 156 (5) ◽  
pp. 577-598 ◽  
Author(s):  
S. Thaler ◽  
J. Eitzinger ◽  
M. Trnka ◽  
M. Možný ◽  
S. Hahn ◽  
...  

AbstractSimulation of the water balance in cropping systems is an essential tool, not only to monitor water status and determine drought but also to find ways in which soil water and irrigation water can be used more efficiently. However, besides the requirement that models are physically correct, the spatial representativeness of input data and, in particular, accurate precipitation data remain a challenge. In recent years, satellite-based soil moisture products have become an important data source for soil wetness information at various spatial-temporal scales. Four different study areas in the Czech Republic and Austria were selected representing Central European soil and climatic conditions. The performance of soil water content outputs from two different crop-water balance models and the Metop Advanced SCATterometer (ASCAT) soil moisture product was tested with field measurements from 2007 to 2011. The model output for soil water content shows that the crop model Decision Support System for Agrotechnology Transfer performs well during dry periods (<30% plant available soil moisture (ASM), whereas the soil water-balance model SoilClim presents the best results in humid months (>60% ASM). Moreover, the model performance is best in the early growing season and decreases later in the season due to biases in simulated crop-related above-ground biomass compared with the relatively stable grass canopy of the measurement sites. The Metop ASCAT soil moisture product, which presents a spatial average of soil surface moisture, shows the best performance under medium soil wetness conditions (30–50% ASM), which is related to low variation in precipitation frequency and under conditions of low-surface biomass (early vegetation season).


1991 ◽  
Vol 10 (1) ◽  
pp. 26-29 ◽  
Author(s):  
A. L. Du Pisani

The characterisation of drought is something which has caused much debate and investigation and is even in the nineties still a thorny problem. This article describes a method whereby drought in natural veld is characterised by using a soil water balance to build a "climatology" of soil water content. The real time situation is then compared to the "soil water climate" and described in terms of probabilities.


Author(s):  
Eugênio Ferreira Coelho ◽  
Marcos de Souza Campos ◽  
Marcelo Rocha dos Santos ◽  
Rafael Dreux Miranda Fernandes ◽  
Jailson Lopes Cruz

Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system. Keywords: localized irrigation, soil water balance, soil water content sensor.


Irriga ◽  
2018 ◽  
Vol 23 (4) ◽  
pp. 667-678
Author(s):  
Alisson Silva ◽  
Valéria Almeida Jatobá ◽  
Francisco Airderson Lima Nascimento ◽  
Allan Radax Freitas Campos ◽  
Jilcélio Almeida

THREE-DIMENSIONAL WATER EXTRACTION IN THE ROOT ZONE OF DRIP-IRRIGATED TOMATO     FRANCISCO AIRDESSON LIMA DO NASCIMENTO¹; ALISSON JADAVI PEREIRA DA SILA²; VALERIA ALMEIDA JATOBA³; ALLAN RADAX FREITAS CAMPOS4 E JILCÉLIO NUNES DE ALMEIDA³   1- Doutorando em Engenharia Agrícola pela Universidade Federal do Recôncavo da Bahia (UFRB),  Rua Rui Barbosa, 710, Centro, 44.380-000, Cruz das Almas, Bahia, Brasil, [email protected];   2- Professor Doutor do Intituto Federal de Educação, Ciência e Tecnologia Baiano (IF Baiano), Campus Governador Mangabeira, Rua Waldemar Mascarenhas, 656, Centro, 44350-000, Gov. Mangabeira, Bahia, Brasil, [email protected]; 3- Licenciado(a) em Ciências Agrárias pelo Intituto Federal de Educação, Ciência e Tecnologia Baiano (IF Baiano), Campus Senhor do Bonfim, Estrada da Igara, s/n, Zona Rural, 48970-000, Senhor do Bonfim, Bahia, Brasil, [email protected]; 4- Doutor em Engenharia Agrícola pela Universidade Federal do Recôncavo da Bahia (URFB),  Rua Rui Barbosa, 710, Centro, 44.380-000, Cruz das Almas, Bahia, Brasil, [email protected].     1 ABSTRACT   Soil water sensing is a common alternative for irrigation management. Due to the difficulty to determine the spatial-temporal variability of water extraction (WE) in the root zone of a crop it is still arbitrary the definition of number and position of water content sensors to be installed for irrigation management purposes. The main objectives of this work are to use Time Domain Reflectometry (TDR) to detail –  in three-dimensions – WE in the root zone of tomato plants cultivated in covered and uncovered soil; and, to evaluate if there are differences in the values of tomato crop evapotranspiration (ET) determined through soil water balance (SWB) with one, two, three and four TDR probe monitoring profiles. The study was carried out under semiarid condition. Tomatoes were grown in the field and two drainage lysimeters were installed in the center of cultivation area. In one lysimeter the soil surface was maintained uncovered, while in the other the soil surface was covered with a black plastic canvas. Eight TDR probes were installed within each lysimeter for the three-dimensional monitoring of soil water content (SWC). WE was estimated with SWC data. It was found that WE in tomato root zone is more intense in regions of greater water availability in the soil, i.e, on wet wet bulb formed inside the soil. There are no differences in the estimation of tomato crop evapotranspiration through soil water balance varying the position of two-dimensional soil water content monitoring. However, when soil water balance is performed in three-dimensions there may be large differences in daily tomato crop evapotranspiration estimation compared to the two-dimensional soil water balance.   Keywords: tomato, sensor placement, irrigation management.      NASCIMENTO, F.A. L.; SILVA, A. J.P.; JATOBA, V.A.;  CAMPOS, A.R.F.; ALMEIDA, J.N EXTRAÇÃO TRI-DIMENSIONAL DE ÁGUA NA ZONA RADICULAR DO TOMATEIRO IRRIGADO POR GOTEJAMENTO   2 RESUMO   O sensoriamento de água no solo é uma comum alternativa para o manejo da irrigação. Devido à dificuldade em se determinar a variabilidade espaço-temporal da extração de água na zona radicular dos cultivos, ainda é arbitrária a definição do número e posicionamento de sensores de água no solo a serem instalados para fins de manejo de irrigação. Diante disso, objetivou-se com o referido trabalho utilizar a Reflectometria no Domínio do Tempo (TDR) para detalhar, em três dimensões, a extração de água pelo tomateiro em cultivo com solo coberto e descoberto, e verificar se existem diferenças nos valores de evapotranspiração da cultura determinados pelo balanço de água no solo com um, dois, três e quatro perfis de monitoramento. O trabalho foi conduzido em condição semiárida nas fases de floração e frutificação da cultura. Montou-se um sistema de aquisição de dados, composto por uma TDR 100 e um datalogger modelo CR 800 para leitura e armazenamento de dados do conteúdo de água no solo. Dois lisímetros de drenagem foram instalados no centro de uma área de cultivo, sendo um mantido com a superfície do solo coberto com lona plástica. Em cada lisímetro, foram distribuídas oito sondas de TDR de modo a formar quatro perfis de monitoramento na zona radicular do tomateiro. A extração de água da zona radicular do tomateiro é mais intensa na região de maior disponibilidade de água, especificamente, na região do bulbo molhado. Não há diferença nos valores de evapotranspiração do tomateiro estimado variando-se a posição do perfil bi-dimensional. Entratanto, ao se comparar valores diários de evapotranspiração do tomateiro estimado com balanço de água no solo realizado em duas e três-dimensões, verificou-se haver  largas diferenças.   Palavras-chave: tomate, extração de água no solo, manejo da irrigação.


2015 ◽  
Vol 12 (9) ◽  
pp. 6783-6820 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. The present study elucidates the nature of the energy gap of EC flux data from winter wheat stands in southwest Germany. During the vegetation periods 2012 and 2013, we continuously measured, in a half-hourly resolution, latent (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. The adjusted LE fluxes were tested against evapotranspiration data (ETWB) calculated using the soil water balance (WB) method. At sixteen locations within the footprint of an EC station, the soil water storage term was determined by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was also continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 vegetation period, the H post-closed LE flux data (ETEC = 3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 20 and 33%, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 30 and 40%, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most vegetation periods on our site, LE is not a~major component of the energy balance gap. Our results indicate that the energy balance gap other energy fluxes and unconsidered or biased energy storage terms.


2016 ◽  
Vol 67 (3) ◽  
pp. 133-144 ◽  
Author(s):  
Reinhard Nolz

Summary Knowing the components of a soil water balance—for example, evapotranspiration, soil water content, and precipitation—is the basis for agricultural water management. Weighing lysimeters and soil water sensors are commonly used to quantify these components. Data can be used to validate common models to estimate evapotranspiration based on meteorological data, for instance. As every measurement device has its own characteristics, it is helpful to assess and improve the performance of a system to obtain best possible data. Recent developments in the processing of lysimeter data allow determining both evapotranspiration and precipitation directly from lysimeter data. Resulting datasets are characterized by a proper accuracy, completeness, and a high temporal resolution. Soil water sensors usually measure a physical property that is related to soil water content or matric potential via a specific calibration function. Hence, measurement accuracy depends not only on this calibration but also on basic physical principles and material properties. Knowing the performance of a device is, therefore, essential for the selection of an adequate sensor arrangement and truthful data interpretation. Advanced soil water monitoring sites combine different sensor types that are integrated into a wireless network to enable real-time data availability and provide a basis for large-scale monitoring.


2016 ◽  
Vol 13 (1) ◽  
pp. 63-75 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. In the present study we cross-checked the evapotranspiration data obtained with the EC method (ETEC) against ET rates measured with the soil water balance method (ETWB) at winter wheat stands in southwest Germany. During the growing seasons 2012 and 2013, we continuously measured, in a half-hourly resolution, latent heat (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. ETWB was estimated based on rainfall, seepage and soil water storage measurements. The soil water storage term was determined at sixteen locations within the footprint of an EC station, by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was additionally continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 growing season, the H post-closed LE flux data (ETEC =  3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 24 and 48 %, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 46 and 70 %, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most observation periods on our site, LE is not a major component of the energy balance gap. Our results indicate that the energy balance gap is made up by other energy fluxes and unconsidered or biased energy storage terms.


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