Peach orchard evapotranspiration in a sandy soil: Comparison between eddy covariance measurements and estimates by the FAO 56 approach

Paço, Teresa A.; Ferreira, Maria Isabel; Conceição, Nuno

doi:10.1016/j.agwat.2006.05.014

Cited by 77 publications

(42 citation statements)

References 28 publications

(28 reference statements)

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“…Similarly, Dragoni et al (2004) showed a significant overestimation (over 15%) of the basal crop coefficients by the FAO-56 method compared to measurements (sap flow). In contrast, Benli et al (2006) and Paç o et al (2006) reported basal crop coefficients that were higher than the tabulated figures. Such deviations in crop coefficients from the generic values are bound to occur as a result of variable crop conditions due to insufficient or non-uniform irrigation, variable crop density and canopy cover, soil salinity and/or agronomic management (Pôç as et al, 2015).…”

Section: Crop Coefficientscontrasting

confidence: 47%

Evaluation of crop coefficients, water productivity, and water balance components for wine grapes irrigated at different deficit levels by a sub-surface drip

Phogat

Skewes

McCarthy

et al. 2017

Agricultural Water Management

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a b s t r a c tAccurate estimation of evapotranspiration (ET) and its partitioning into transpiration and evaporation is fundamental for improving water management practices in water-limited environments and under deficit irrigation conditions. This investigation was conducted to estimate the water balance and ET components of subsurface drip (SDI) irrigated Chardonnay wine grapes for two seasons (2010-2011 and 2011-2012) using a numerical model (HYDRUS-2D). Treatments involved the application of different volumes [51% (I 1 ), 64% (I 2 ), 77% (I 3 ), and 92% (I 4 ) of normal application] of water for irrigation. A modified version of the FAO-56 dual crop coefficient approach was used to generate daily transpiration and evaporation as inputs to the HYDRUS-2D model. The calibrated and validated model produced estimates of actual evapotranspiration (ET Cact ), actual transpiration (T pact ), and actual evaporation (E sact ), and deep percolation under varied irrigation applications. The model-simulated values were then used to estimate actual crop coefficients (K cact and K cbact ), and water productivity of wine grape under different deficit irrigation conditions. Seasonal ET Cact simulated by HYDRUS-2D for different treatments varied between 239 and 382 mm. However, seasonal evaporation accounted for 44-59% of seasonal ET Cact losses in different treatments. The modelled daily transpiration rate in I 4 treatment (T p4act ) varied from 0.11-2.74 mm/day. Deep percolation accounted for 35-40% of the total water applied by rainfall and irrigation. The mean value of actual crop coefficient (K cact ) estimated by HYDRUS-2D simulated ET C act over the two seasons was 0.27, which matched with other investigations. Similarly, values of K cbact for initial, mid and end stages were 0.13, 0.27 and 0.14, respectively. Monthly values of evaporation coefficient (K e ) ranged from 0.1 to 0.32, with a mean value of 0.18. Water productivity with respect to ET losses (WPET C ) ranged from 5.9 to 6.2 kg/m 3 of water use. However, water productivity for transpiration (WPT C ) almost doubled as compared to WPET C in all treatments. The impact of deficit irrigation on berry juice composition (Brix, pH and titratable acidity) was lower than the inter-seasonal variability. These results can help develop better irrigation management strategies for SDI irrigated wine grapes under water scarce conditions.

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Section: Crop Coefficientscontrasting

confidence: 47%

Evaluation of crop coefficients, water productivity, and water balance components for wine grapes irrigated at different deficit levels by a sub-surface drip

Phogat

Skewes

McCarthy

et al. 2017

Agricultural Water Management

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show abstract

“…In the majority of the studies, the K c values are obtained by the single crop coefficient approach, where crop transpiration and soil evaporation are combined into a single K c coefficient. Infrequently, the dual crop coefficient (k cb ) approach is used, where the effects of crop transpiration and soil evaporation are determined independently [34][35][36][37][38]. The FAO-56 method is based on the use of crop specific parameters.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of Irrigation Schemes by Remote Sensing: Phenology versus Retrieval of Biophysical Variables

et al. 2014

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Abstract:The appraisal of crop water requirements (CWR) is crucial for the management of water resources, especially in arid and semi-arid regions where irrigation represents the largest consumer of water, such as the Doukkala area, western Morocco. Simple and (semi) empirical approaches have been applied to estimate CWR: the first one is called K c -NDVI method, based on the correlation between the Normalized Difference Vegetation Index (NDVI) and the crop coefficient (K c ); the second one is the analytical approach based on the direct application of the Penman-Monteith equation with reflectance-based estimates of canopy biophysical variables, such as surface albedo (r), leaf area index (LAI) and crop height (h c ). A time series of high spatial resolution RapidEye (REIS), SPOT4 (HRVIR1) and Landsat 8 (OLI) images acquired during the 2012/2013 agricultural season has been used to assess the spatial and temporal variability of crop evapotranspiration ET c and biophysical variables. The validation using the dual crop coefficient approach (K cb 5816 adequacy between water requirements and allocations showed that CWR were much larger than allocated surface water for the entire area, with this difference being small at the beginning of the growing season. Even smaller differences were observed between surface water allocations and Irrigation Water Requirements (IWR) throughout the irrigation season. Finally, surface water allocations were rather close to Net Irrigation Water Requirements (NIWR).

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“…Wilson et al (2002) summarized results from 22 flux sites of measurements and indicated a general lack at most of the sites, with a mean imbalance of about 20%. This problem was also reported by Twine et al (2000), Paço et al (2006) and Testi et al (2006), which can be associated with inaccurate measurements of R n and G, but not completely explained by these inaccuracies, because EC systems have their own sources of error (Twine et al 2000). Following Allen (2008), the lack of the closure in EC data can be solved by using a simple regression method that accounts for all sources of errors, assuming that R n is the most accurate energy balance component in the semi-arid conditions.…”

Section: Orchard Energy Balancementioning

confidence: 48%

Five methods to interpret field measurements of energy fluxes over a micro-sprinkler-irrigated mango orchard

Teixeira

Bastiaanssen

2010

Irrig Sci

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Energy balance measurements were carried out in a mango orchard during two growing seasons in the semi-arid region of Brazil. The actual evapotranspiration (ET) was acquired by eddy correlation (EC) and Bowen ratio energy balance (BR) techniques. The daily energy balance closure in the EC measurements showed an average gap of 12%, with a root mean square error (RMSE) of. Three different correction procedures were tested for closing the energy balance from the EC system: (1) the surface energy balance residual method (RES), (2) the Bowen ratio determined from the EC fluxes, the combination approach (EC_BR), and (3) a new regression energy balance closure technique (REG). All closing energy balance methods presented good correlation with the direct EC measurements, but the trends were not similar. The latent heat fluxes estimated by the BR method-kE BR -were higher than those from the direct EC measurements-kE EC . When using the RES method, the half-hour kE EC measurements represented around 88% of the kE RES values, as the uncertainties of net radiation-R n -and soil heat fluxes-G-are propagated into the RES method. The latent heat flux derived from the combination approach-kE EC_BR -also brings these uncertainties, being the agreements comparable with those for RES method. It was therefore concluded that a single correction method for EC measurements considering only the latent and sensible heat fluxes does not exist. A new way to solve the lack of energy balance closure from EC techniques was tested by means of a curve fitting, the REG method. Considering the REG corrections applied to the energy balance components involving all periods of the day and the average conditions of the two growing seasons, half-hour values of kE EC were overmeasured by 18%, H EC was undermeasured by 17%, and G values required a correction of 466%. The REG method appeared promising because it considers different weights for all energy balance components in the optimization process. Taking the REG results for the drier second growing season as a reference, it was concluded that seasonal ET values by the other methods in mango orchard ranged from 7 to 28% higher, showing that turbulent flux measurements lack accuracy for executing on-farm watersaving programmes and calibrating transient soil water flow models.

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Peach orchard evapotranspiration in a sandy soil: Comparison between eddy covariance measurements and estimates by the FAO 56 approach

Cited by 77 publications

References 28 publications

Evaluation of crop coefficients, water productivity, and water balance components for wine grapes irrigated at different deficit levels by a sub-surface drip

Evaluation of crop coefficients, water productivity, and water balance components for wine grapes irrigated at different deficit levels by a sub-surface drip

Monitoring of Irrigation Schemes by Remote Sensing: Phenology versus Retrieval of Biophysical Variables

Five methods to interpret field measurements of energy fluxes over a micro-sprinkler-irrigated mango orchard

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