Crop coefficient changes with reference evapotranspiration for highly canopy-atmosphere coupled crops

Marin, Fábio Ricardo; Angelocci, Luiz Roberto; Nassif, Daniel Silveira Pinto; Costa, Leandro G.; Vianna, Murilo dos Santos; Carvalho, Kassio S.

doi:10.1016/j.agwat.2015.09.010

Cited by 50 publications

(45 citation statements)

References 22 publications

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“…In addition, the results of Flumignan et al (2011) and Marin et al (2016) demonstrate the strong dependence between Kc and Kcb on the high atmospheric demand represented by ETo values. This implies the existence of a higher transpiration control by the plant through its stomatal closure under such conditions.…”

Section: Resultsmentioning

confidence: 93%

Water Demand, Crop Coefficient and Uncoupling Factor of Cowpea in the Eastern Amazon

et al. 2017

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-Cowpea has great socioeconomic importance in the northeastern part of Pará state. However, in order to provide suitable irrigation management during the dry period this region requires solid information regarding water demand by regional crops. This research aims to determine the water demand, the crop coefficient (Kc) and the uncoupling factor during the different development stages of cowpea in the northeast of Pará. The crop evapotranspiration (ETc) was measured by drainage lysimeters. This information was coupled to the reference evapotranspiration (ETo) to obtain the crop coefficients, which were used to adjust the model function of accumulated degree-days and the leaf area index (LAI). The uncoupling factor was estimated to indicate the factors that control evapotranspiration. The ETc values reached a cumulative total of 267.73 mm ± 10.21 mm during the cowpea cycle. The average value of the uncoupling factor was 0.66. This indicates that the cowpea crop does not fully uncouple from the atmosphere underneath the climatic conditions in northeast Pará. The cowpea Kc values presented averages of 0.8, 1.4 and 0.8 in the vegetative phase, reproductive phase and final stage, respectively. The Gaussian model showed an excellent fit for the estimation of Kc values based on accumulated degree days and the LAI. These amounts differ from others found in the literature. Therefore, it reinforces the necessity for an assessment of crop coefficients under local conditions and for the employment of more precise methods.Keywords: Vigna unguiculata L. Walp. Penman-montheith. Lysimeters. Uncoupling factor. Evapotranspiration. DEMANDA HÍDRICA, COEFICIENTE DE CULTIVO E FATOR DE DESACOPLAMENTO DOFEIJÃO CAUPI NA AMAZÔNIA ORIENTAL RESUMO -O feijão caupi possui grande importância sócioeconômica para o nordeste paraense, porém, a região necessita de informações seguras quanto demanda hídrica, para promover um manejo adequado de irrigação no período considerado mais seco do ano. Assim, o objetivo da pesquisa foi determinar a demanda hídrica, coeficiente da cultura (Kc) e fator de desacoplamento nos diferentes estádios de desenvolvimento do feijão caupi no nordeste paraense. Com a evapotranspiração da cultura (ETc), obtida por meio de lisímetros de drenagem, e a evapotranspiração de referência (ETo) foram obtidos os coeficientes de cultura (Kc), utilizados posteriormente, para ajustar modelos em função dos graus dias acumulados (GD) e índice de área foliar (IAF), o fator de desacoplamento foi estimado para indicar os fatores que estão governando a evapotranspiração.

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Section: Resultsmentioning

confidence: 93%

Water Demand, Crop Coefficient and Uncoupling Factor of Cowpea in the Eastern Amazon

et al. 2017

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“…In spite of technological advances in water supply, irrigation management is still inefficient in most areas. The lack of information on crop water needs is one of the main causes of inefficient water use (Marin et al, 2016). Crop water consumption, known as crop evapotranspiration (ETc), depends directly on atmospheric energy demand, the soil water content and plant resistance to losing water to the atmosphere (Pereira et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

Sanches

Souza

Jesus

et al. 2019

Sci. agric. (Piracicaba, Braz.)

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Crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), representing the phenological effects on crop water consumption. Kc is fundamental to estimating ETc by agrometeorological methods. This research study aimed to determine Kc and ETc values for Guinea grass (Megathyrsus maximus cv. Mombaça) and Bermuda grass (Cynodon spp.), both single cropped for one year and overseeded with black oat (Avena strigosa) and ryegrass (Lolium multiflorum) during fall/winter. The experiment in the field comprised four plots, two for each tropical forage, with and without overseeding. At the center of each plot, there was a weighing lysimeter with an automated system for data collection. ETc was measured daily over four seasons following the lysimetric method; ETo was calculated using the Penman-Monteith equation. ETc and ETo values were used to estimate Kc values. The single cropped Guinea grass showed the highest values for ETc, with mean ETc and Kc of 3.99 mm d-1 and 1.07, respectively. The single cropped Bermuda grass showed ETc and Kc values of 3.57 mm d-1 and 0.96, respectively. The results of paired t-testing for Kc showed no significant differences (p = 0.05) between single cropped and intercropped for both Guinea grass and Cynodon spp. During winter, intercropped Guinea grass did not show an ETc significantly higher than single cropped Guinea grass, with mean Kc values 0.98 for intercropped and 1.10 for single cropped. Similarly, Bermuda grass did not show significant differences between mean Kc values for intercropped (1.02) and single cropped (1.00).

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“…Actual water evapotranspirated by a crop (ETc) is not only determined by ETp; an estimation of transpiration canopy is also needed. This estimation corresponds to the concept of leaf area index (IAF; m 2 of transpiring leaves/m 2 of cultivated land) [23,28,32]; for irrigation scheduling purposes, this concept is generally expressed as the "crop coefficient" (Kc) [27,29,[33][34][35] which in fact is a time function, since IAF varies from bare soils at the end of winter (Kc initial = 0.1-0.15), representing direct soil surface evaporation, up to Kc max = 0.8-1.2), when the maximal IAF is attained. The Kc = (t) function can be represented by a double sigmoid curve (Figure 2) for the initial three crop phenology stages (budbreak, flowering, and veraison) [36,37]; a constant maximal value from veraison to harvest, and a linear decline for the postharvest irrigation stage, reaching a Kc final = Kc initial [37].…”

Section: Crop Et Coefficients [Kc = ƒ(Crop Phenology)]mentioning

confidence: 99%

Agronomic Operation and Maintenance of Field Irrigation Systems

Gurovich¹,

Riveros²

2019

Irrigation - Water Productivity and Operation, Sustainability and Climate Change

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Worldwide experience indicates that projected economic returns on investments in field irrigation systems are seldom obtained by farmers, due to improper strategies on irrigation scheduling, lack of operational control, and limited feedback on the actual performance of irrigation systems, in terms of application efficiency and uniformity. An approach to dynamic integration of soil hydrodynamic characteristics, potential evapotranspiration, and crop leaf area index evolution throughout the irrigation season is detailed, oriented to integrate smart water management strategies and techniques in the operation and maintenance of farm irrigation systems. This dynamic integrative platform has been used in Perú and México by actual farming companies producing table grapes, wine grapes, avocado, and bell peppers exported to international markets; this chapter documents its practical results in terms of water and energy savings, crop yield, and fruit quality.

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Crop coefficient changes with reference evapotranspiration for highly canopy-atmosphere coupled crops

Cited by 50 publications

References 22 publications

Water Demand, Crop Coefficient and Uncoupling Factor of Cowpea in the Eastern Amazon

Water Demand, Crop Coefficient and Uncoupling Factor of Cowpea in the Eastern Amazon

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

Agronomic Operation and Maintenance of Field Irrigation Systems

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