scholarly journals VARIAÇÃO SAZONAL NA EVAPOTRANSPIRAÇÃO DE PLANTAS JOVENS DE LIMA ÁCIDA ‘TAHITI’

Irriga ◽  
2006 ◽  
Vol 11 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Cláudio Ricardo da Silva ◽  
José Alves Júnior ◽  
Tonny José Araújo da Silva ◽  
Marcos Vinícius Folegatti ◽  
Luis Fernando de Souza Magno Campeche
Keyword(s):  
Seasonal Variation ◽  
Seasonal Variations ◽  
Crop Coefficient ◽  
Soil Evaporation ◽  
Field Conditions ◽  
Water Requirements ◽  
Experimental Area ◽  
Acid Lime ◽  
Daily Evapotranspiration ◽  
Crop Coefficients

VARIAÇÃO SAZONAL NA EVAPOTRANSPIRAÇÃO DE PLANTAS JOVENS DE LIMA ÁCIDA ‘TAHITI’  Cláudio Ricardo da Silva1; José Alves Júnior1; Tonny José Araújo da Silva1; Marcos Vinícius Folegatti1; Luis Fernando de Souza Magno Campeche21Departamento de Engenharia Rural, Escola Superior de Agricultura Luiz de Queiróz,  Universidade de São Paulo,  Piracicaba-SP, [email protected] de Engenharia Agronômica,  Universidade Federal de Sergipe  1 RESUMO O objetivo deste trabalho foi estudar a variação sazonal diária e horária na evapotranspiração de plantas jovens de lima ácida ‘Tahiti’ sob condições de campo. O estudo foi conduzido em Piracicaba, durante o inverno de 2003 e verão de 2004. Utilizou-se um lisímetro de pesagem eletrônica de 2,7 mde diâmetro e 0,8 mde profundidade com uma planta de dois anos de idade, localizado no centro da área experimental com 322 plantas. Todas as plantas do pomar foram irrigadas por quatro gotejadores autocompensantes, inclusive a do lisímetro. Os resultados permitiram verificar que no período de verão a média da evapotranspiração da cultura (ETc) foi de 1,50 mm dia-1 decrescendo a 0,66 mm dia-1 nos meses de inverno. O coeficiente de cultivo (Kc) médio obtido foi de 0,36 e 0,22 durante o período de verão e inverno, respectivamente. A ETc máxima para o período de inverno ocorreu às 14:00 h enquanto que no verão foi às 12:00 h. Além disso, ocorreram perdas por evaporação diária noturna de 17,4 % e 13,4% da ETc para o período de inverno e verão respectivamente. A curva de evaporação do solo (Ke) foi semelhante em ambos os períodos estudados. UNITERMOS: citros, lisímetro, coeficiente de cultivo, demanda hídrica  SILVA, C. R. da; ALVES JÚNIOR, J.; SILVA, T. J. A. da; FOLEGATTI, M. V.; CAMPECHE, L. F. de S. M.; SEASONAL VARIATION IN EVAPOTRANSPIRATION OF YOUNG ‘TAHITI’ACID LIME TREES  2 ABSTRACT             The objective of this study was to investigate seasonal variations in hourly and daily evapotranspiration (ETc) of acid lime ‘Tahiti’ trees under field conditions, defining values of crop coefficients. The study was carried out in Piracicaba, Brazil, during the winter of 2003 and the summer of 2004. Aweighing lysimeter of 2.7 mdiameter and 0.8 mdepth was planted with a two-year-old tree that was located at the center of an experimental area with 322 trees. The lysimeter tree was irrigated, like others in the plot, by four pressure compensated emitters. The average ETc was 1.50 mmday-1 in the summer and dropped to 0.66 mm day-1 in winter months. The average seasonal crop coefficient (Kc) was 0.36 and 0.22 for summer and winter, respectively. The maximum Etc time was at noon in the summer and at 2 pm in the winter. Moreover, night soil evaporation represented 17.4% and 13.4% of daily ETc in winter and summer. The soil evaporation curve  (Ke) in both seasons showed similar results.  KEYWORDS: citrus, lysimeter, crop coefficient, water requirements

scholarly journals Water requirement and crop coefficients of sorghum in Apodi Plateau

2021 ◽  
Vol 25 (10) ◽  
pp. 684-688
Author(s):  
João G. A. Lima ◽  
José Espínola Sobrinho ◽  
José F. de Medeiros ◽  
Paula C. Viana ◽  
Rudah M. Maniçoba
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Irrigation Management ◽  
High Growth ◽  
Crop Coefficient ◽  
Northeastern Brazil ◽  
Crop Evapotranspiration ◽  
Water Requirements ◽  
Total Crop ◽  
Crop Coefficients

ABSTRACT Sorghum is of significant economic importance for Northeastern Brazil, since it exhibits high growth rates in regions with irregular rainfall distribution and high temperatures, and is an alternative to corn, which has greater water requirements. Despite being a traditional crop in the region, there are few studies on irrigation management in the Apodi plateau. The aim of this study was to determine the evapotranspiration of the crop and the crop coefficient (Kc) for the different stages of sorghum growth in two cycles, and establish the relationship between the Kc and the normalized difference vegetation index (NDVI) obtained by radiometry. Two weighing lysimeters were used to estimate crop evapotranspiration (ETc). Reference evapotranspiration (ETo) was estimated by the Penman-Monteith method (FAO) and the crop coefficient determined using two methodologies: simple Kc and dual Kc. Total crop evapotranspiration in the two cycles was 452 and 557 mm. The ETc value was 23% higher in the second cycle compared to the first. The maximum Kc values for the first and second cycles were 1.21 and 1.35, respectively, using the dual Kc methodology. The linear relationship found between the Kc values and the NDVI allows monitoring and estimating the water requirements of the crop.

scholarly journals Simplified Water Requirement Calculators for Fruits and Vegetables

2016 ◽  
Vol 26 (4) ◽  
pp. 530-541 ◽  
Author(s):  
Brent Rowell ◽  
Mar Lar Soe
Keyword(s):  
Drip Irrigation ◽  
Fruits And Vegetables ◽  
Canopy Cover ◽  
Crop Coefficient ◽  
Climatic Data ◽  
Vegetable Crops ◽  
Rotating Disc ◽  
Water Requirements ◽  
Water Wheel ◽  
Crop Coefficients

New users of drip irrigation in Myanmar had no idea how much water to apply to their crops with drip and could not afford tensiometers or other soil moisture monitoring tools. The concept of a simple paper calculator was born out of their need for an easy-to-use yet inexpensive tool to estimate horticultural crop water requirements. We used a generalized crop coefficient and growth stage approach together with average evapotranspiration (ET) for the vegetable crops “Water Wheel” calculator and a canopy cover approach for the tree fruit calculator. Differences among published crop coefficients are relatively small for a large number of vegetables and single coefficients were used for groups of crops without putting farmers’ crops at risk. Vegetable crops were divided into two groups based on whether water requirements during harvest remained the same as for the flowering and fruiting stage or were reduced for the harvest period. A simplified canopy cover approach was used to determine water requirements for perennial fruit, tree, and vine crops. Our faith in the ability of farmers to make their own adjustments gave us confidence to simplify ET-based water requirements and make them available in the form of simple rotating disc calculators printed in color on laminated card stock. The calculators were welcomed by our staff and enabled them to provide reasonably reliable recommendations for new users of drip irrigation. When surveyed, field staff responded that 74% of farmers they advised followed Water Wheel recommendations. Rough estimates of fruit and vegetable water requirements reached a large number of new drip users in a form they could easily understand, thereby lowering adoption barriers for an unfamiliar technology. This paper describes the Water Wheel concept and design so nonspecialists might develop their own calculators using local climatic data.

scholarly journals Reduction of predictive uncertainty in estimating irrigation water requirement through multi-model ensembles and ensemble averaging

2015 ◽  
Vol 8 (4) ◽  
pp. 1233-1244 ◽  
Author(s):  
S. Multsch ◽  
J.-F. Exbrayat ◽  
M. Kirby ◽  
N. R. Viney ◽  
H.-G. Frede ◽  
...  
Keyword(s):  
Irrigation Water ◽  
Model Uncertainty ◽  
Parametric Uncertainty ◽  
Crop Coefficient ◽  
Water Requirement ◽  
Irrigation Water Requirement ◽  
Ensemble Averaging ◽  
Water Requirements ◽  
Crop Coefficients ◽  
Model Parametric Uncertainty

Abstract. Irrigation agriculture plays an increasingly important role in food supply. Many evapotranspiration models are used today to estimate the water demand for irrigation. They consider different stages of crop growth by empirical crop coefficients to adapt evapotranspiration throughout the vegetation period. We investigate the importance of the model structural versus model parametric uncertainty for irrigation simulations by considering six evapotranspiration models and five crop coefficient sets to estimate irrigation water requirements for growing wheat in the Murray–Darling Basin, Australia. The study is carried out using the spatial decision support system SPARE:WATER. We find that structural model uncertainty among reference ET is far more important than model parametric uncertainty introduced by crop coefficients. These crop coefficients are used to estimate irrigation water requirement following the single crop coefficient approach. Using the reliability ensemble averaging (REA) technique, we are able to reduce the overall predictive model uncertainty by more than 10%. The exceedance probability curve of irrigation water requirements shows that a certain threshold, e.g. an irrigation water limit due to water right of 400 mm, would be less frequently exceeded in case of the REA ensemble average (45%) in comparison to the equally weighted ensemble average (66%). We conclude that multi-model ensemble predictions and sophisticated model averaging techniques are helpful in predicting irrigation demand and provide relevant information for decision making.

scholarly journals Estimation of crop water requirements: extending the one-step approach to dual crop coefficients

2015 ◽  
Vol 12 (5) ◽  
pp. 4933-4963 ◽  
Author(s):  
J. P. Lhomme ◽  
N. Boudhina ◽  
M. M. Masmoudi ◽  
A. Chehbouni
Keyword(s):  
Surface Resistance ◽  
Crop Coefficient ◽  
Soil Surface ◽  
Stomatal Resistance ◽  
Crop Water ◽  
Water Requirements ◽  
Crop Water Requirements ◽  
One Step ◽  
Crop Coefficients ◽  
Monteith Equation

Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a "two-step" approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation; then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a "one-step" approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation, but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.

scholarly journals Applying the FAO-56 Dual Kc Method for Irrigation Water Requirements over Large Areas of the Western U.S.

2020 ◽  
Vol 63 (6) ◽  
pp. 2059-2081
Author(s):  
Richard G. Allen ◽  
Clarence W. Robison ◽  
Justin Huntington ◽  
James L. Wright ◽  
Ayse Kilic
Keyword(s):  
Climate Change ◽  
Irrigation Water ◽  
Crop Coefficient ◽  
The State ◽  
Future Climate Change ◽  
Weather Station ◽  
Water Requirements ◽  
Wide Range ◽  
Crop Coefficients ◽  
Agricultural Areas

HighlightsThe FAO-56 dual crop coefficient procedure was applied over the entire agricultural areas of Idaho and Nevada to determine evapotranspiration (ET) and net irrigation water requirements (IWR).Basal crop coefficients were expressed as functions of normalized cumulative growing degree days.ET during dormant seasons was included in the estimates.The procedure was applied to a U.S. West-wide study of climate change effects on ET and IWR.Abstract. The FAO-56 dual crop coefficient procedure was used to determine evapotranspiration (ET) and net irrigation water requirements for all agricultural areas of the states of Idaho and Nevada and in a western U.S. study on effects of climate change on future irrigation water requirements. The products of the applications are for use by state governments for water rights management, irrigation system planning and design, wastewater application system design and review, hydrologic water balances, and groundwater modeling. The products have been used by the U.S. federal government for assessing impacts of current and future climate change on irrigation water demands. The procedure was applied to data from more than 200 weather station locations across the state of Idaho, 200 weather station locations across the state of Nevada, and eight major river basins in the western U.S. for available periods of weather records. Estimates were made over daily, monthly, and annual time intervals. Methods from FAO-56 were employed for calculating reference ET and crop coefficients (Kc), with ET calculations performed for all times of the calendar year including winter. Expressing Kc as a function of thermal-time units allowed application across a wide range of local climates and elevations. The ET estimates covered a wide range of agricultural crops grown in the western U.S. plus a number of native plant systems, including wetlands, rangeland, and riparian trees. Evaporation was estimated for three types of open-water surfaces ranging from deep reservoirs to small farm ponds. Keywords: Consumptive use, Dual crop coefficient, Evapotranspiration, FAO-56, Irrigation water requirements.

scholarly journals ESTIMATING WATER REQUIREMENTS OF LANDSCAPE PLANTINGS

HortScience ◽  
1992 ◽  
Vol 27 (12) ◽  
pp. 1263f-1263
Author(s):  
L.R. Costello ◽  
N.P. Matheny ◽  
J.R. Clark
Keyword(s):  
Water Use ◽  
Water Loss ◽  
Reference Evapotranspiration ◽  
Crop Coefficient ◽  
Vegetation Density ◽  
Water Requirements ◽  
Landscape Water ◽  
Crop Coefficients

Since it is unlikely that crop coefficients will be established for landscape plantings, a method to estimate landscape water requirements is proposed. By evaluating three factors that significantly influence water use-species planted, vegetation density, and site microclimate-and assigning numerical values to each, an estimate of a landscape crop coefficient (or landscape coefficient, KL) can be calculated. An estimate of evapotranspirational water loss for landscapes is then the product of the landscape coefficient multiplied by the reference evapotranspiration. This paper presents values for the above three factors and discusses the rationale for each. Examples using the landscape coefficient formula are included, as well as a discussion of special considerations relative to its use.

scholarly journals Estimate of the crop coefficient for Eucalyptus cultivated under irrigation during initial growth

CERNE ◽  
2013 ◽  
Vol 19 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Maria Emília Borges Alves ◽  
Everardo Chartuni Mantovani ◽  
Gilberto Chohaku Sediyama ◽  
Júlio César Lima Neves
Keyword(s):  
Growth Stage ◽  
Crop Coefficient ◽  
Field Measurements ◽  
Crop Productivity ◽  
Initial Growth ◽  
Water Requirements ◽  
Mean Values ◽  
Soil Fraction ◽  
Consistent Method ◽  
Crop Coefficients

The expansion in areas planted with eucalyptus crops has raised concern about the effects these may have on water resources and existing correlations between water use and crop productivity, which calls for better understanding of water requirements by plant species. The objective of this study was to determine the water requirements of an irrigated eucalyptus crop, having the estimated dual crop coefficient (dual Kc) as a reference. Mean values found for estimated crop coefficients were 0.57, 0.13 and 0.70 for Ke, Kcb and Kc respectively during initial growth stage, and 0.01, 0.81 and 0.82 for Ke, Kcb and Kc respectively during the mid-season stage. The methodology used in this study is not intended to replace field measurements for development of Kc curves. However, it provides a consistent method to evaluate values measured while providing means for estimating variations in values of Kc according to change in the soil fraction covered by vegetation.

scholarly journals MEDIDAS DA EVAPOTRANSPIRAÇÃO (ETc) E COEFICIENTE DE CULTURA (Kc) DO CRAVO-DE-DEFUNTODENTRO E FORA DE AMBIENTE PROTEGIDO.

Irriga ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 155-165 ◽  
Author(s):  
Millena Ariana Boueri ◽  
Raúl Andres Martinez ◽  
Dalva Martinelli Cury Lunardi
Keyword(s):  
Initial Phase ◽  
Culture Medium ◽  
Crop Coefficient ◽  
Crop Evapotranspiration ◽  
Vegetative Development ◽  
Radiation Reduction ◽  
Development Stages ◽  
Experimental Area ◽  
Crop Coefficients

MEDIDAS DA EVAPOTRANSPIRAÇÃO (ETc) E COEFICIENTE DE CULTURA (Kc) DO CRAVO-DE-DEFUNTODENTRO E FORA DE AMBIENTE PROTEGIDO.  Millena Ariana Boueri; Raúl Andres Martinez; Dalva Martinelli Cury LunardiDepartamento de Ciências Ambientais, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, SP, [email protected]  1 RESUMO O objetivo deste trabalho foi avaliar o consumo de água do cravo-de-defunto (Tagetes sp.), dentro e fora de ambiente protegido, com uso de lisímetros de lençol freático constante, para determinação da evapotranspiração da cultura (ETc) e dos coeficientes de cultura (Kc) em todos os seus estádios de desenvolvimento. O experimento foi realizado na área experimental do Departamento de Recursos Naturais – Setor Ciências Ambientais da Faculdade de Ciências Agronômicas da Universidade Estadual Paulista, Campus de Botucatu, no período de 21/05/02 a 09/08/02. A área experimental foi constituída de duas áreas de 280m2, sendo uma na condição de campo e a outra em ambiente protegido tipo arco, com cobertura de polietileno de baixa densidade (PEBD), difusor de luz, com 150mm de espessura, tendo nas laterais sombrite com 50% de redução da radiação solar. Os resultados mostraram que a ETc total, para um ciclo de 81 dias, foi de 115 e 119mm, nas condições de ambiente protegido e campo, respectivamente, com médias de 1,4 e 1,5mm d-1. Foram observados valores médios de Kc de 0,48 e 0,71 na fase inicial, 0,87 e 0,93 no desenvolvimento vegetativo, com máximos de 1,15 e 0,85 na floração, e 0,94 e 0,70 no final do ciclo, nas condições de ambiente protegido e campo, respectivamente. UNITERMOS: lisímetro; Tagetes sp.  BOUERI, M. A.; MARTINEZ, R. A.; CURY LUNARDI, D. M. CROP EVAPOTRANSPIRATION (ETc) AND CROP COEFFICIENT (Kc) MEASUREMENTS OF TAGETES, INSIDE AND OUTSIDE GREENHOUSE  2 ABSTRACT The objective of this work was to measure the water consumption of the Tagetes sp. crop, inside and outside of greenhouse, through water table lysimeters, for determination of the crop evapotranspiration (ETc) and crop coefficients (Kc) in all its development stages. The experiment was carried in the experimental area of the Department of Natural Resources - Section Environmental Sciences of the Faculdade de Ciências Agronômicas, UNESP, Botucatu, SP, 21/05/02 to 09/08/02. The experimental area was constituted of two areas of 280m2, being one in the field condition and the other in arch type greenhouse, with polyethylene low density (PEBD) covering, light difusor, with 150mm of thickness, and polypropylene screen with 50% of solar radiation reduction in the lateral. The results showed that the total ETc, for a cycle of 81 days, was of 115 and 119mm, in the conditions of greenhouse and field, respectively, with averages of 1.4 and 1.5mm d-1. The crop coefficient varied in agreement with the stages of development of the culture, medium values of 0.48 and 0.71 having been observed in the initial phase, 0.87 and 0.93 in the vegetative development, with maxima of 1.15 and 0.85 in the blossom, and 0.94 and 0.70 in the end of the cycle, in the conditions of greenhouse and field, respectively. KEYWORDS: lisymeter; Tagetes sp.

scholarly journals Estimation of crop water requirements: extending the one-step approach to dual crop coefficients

2015 ◽  
Vol 19 (7) ◽  
pp. 3287-3299 ◽  
Author(s):  
J. P. Lhomme ◽  
N. Boudhina ◽  
M. M. Masmoudi ◽  
A. Chehbouni
Keyword(s):  
Surface Resistance ◽  
Crop Coefficient ◽  
Soil Surface ◽  
Stomatal Resistance ◽  
Crop Water ◽  
Water Requirements ◽  
Crop Water Requirements ◽  
One Step ◽  
Crop Coefficients ◽  
Monteith Equation

Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a two-step approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation, then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a one-step approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.

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