Academic literature on the topic 'FAO-56 dual crop coefficient method'
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Journal articles on the topic "FAO-56 dual crop coefficient method"
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DeJonge, Kendall C., and Kelly R. Thorp. "Implementing Standardized Reference Evapotranspiration and Dual Crop Coefficient Approach in the DSSAT Cropping System Model." Transactions of the ASABE 60, no. 6 (2017): 1965–81. http://dx.doi.org/10.13031/trans.12321.
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Abstract. While methods for estimating reference evapotranspiration (ETo or ETr) and subsequent crop ET (ETc) via crop coefficient (Kc) and dual crop coefficient (Kcb, Ke) methods have been standardized since 2005 and 1998, respectively, the current version of the DSSAT cropping system model (CSM) has not been updated to fully implement these methods. In this study, two major enhancements to the model’s ET routines were evaluated: (1) addition of the ASCE Standardized Reference Evapotranspiration Equation so that both grass and alfalfa reference ET were properly calculated using the most recent reference ET standard and (2) addition of the FAO-56 dual crop coefficient approach to determine potential ET, which combined an evaporative coefficient (Ke) for potential evaporation with a dynamic basal crop coefficient (Kcb) for potential transpiration as a function of simulated leaf area index. Previously published data sets for maize in Colorado (five years) and cotton in Arizona (seven years) were used to parameterize the model. Simulations of ETo were compared to outputs from Ref-ET software, and simulated crop coefficients were contrasted among three crop coefficient methods: the current approach (Kcs), a previously published adjustment to the model’s Kc equation (Kcd), and a new dual Kc approach that follows FAO-56 explicitly (Kcb). Results showed that crop coefficient simulations with the new ETo-Kcb method better mimicked theoretical behavior, including spikes in the soil evaporation coefficient (Ke) due to irrigation and rainfall events and basal crop coefficient response as associated with simulated crop growth. Simulated ETc and yield with the new ETo-Kcb method were up to 4% higher and 28% lower for cotton and up to 13% higher and 26% lower for maize, respectively, than that with the current ETo-Kcs method, indicating that the seasonal ETc effects were minimal while yield effects were more substantial. Use of FAO-56 concepts and current ET standards in DSSAT-CSM demonstrated a well-accepted ET benchmark to guide assessment of other ET methods in the model and made the model much more conceptually relevant to irrigation and ET specialists. Keywords: Cotton, DSSAT, Evaporation, Evapotranspiration, FAO-56, Maize, Reference crop ET, Standardization, Transpiration.
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Allen, Richard G., Clarence W. Robison, Justin Huntington, James L. Wright, and Ayse Kilic. "Applying the FAO-56 Dual Kc Method for Irrigation Water Requirements over Large Areas of the Western U.S." Transactions of the ASABE 63, no. 6 (2020): 2059–81. http://dx.doi.org/10.13031/trans.13933.
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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.
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Lhomme, J. P., N. Boudhina, M. M. Masmoudi, and A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients." Hydrology and Earth System Sciences 19, no. 7 (July 30, 2015): 3287–99. http://dx.doi.org/10.5194/hess-19-3287-2015.
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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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Lhomme, J. P., N. Boudhina, M. M. Masmoudi, and A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients." Hydrology and Earth System Sciences Discussions 12, no. 5 (May 13, 2015): 4933–63. http://dx.doi.org/10.5194/hessd-12-4933-2015.
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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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Allen, Richard G., Luis S. Pereira, Martin Smith, Dirk Raes, and James L. Wright. "FAO-56 Dual Crop Coefficient Method for Estimating Evaporation from Soil and Application Extensions." Journal of Irrigation and Drainage Engineering 131, no. 1 (February 2005): 2–13. http://dx.doi.org/10.1061/(asce)0733-9437(2005)131:1(2).
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Pozníková, Gabriela, Milan Fischer, Eva Pohanková, and Miroslav Trnka. "Analyses of Spring Barley Evapotranspiration Rates Based on Gradient Measurements and Dual Crop Coefficient Model." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 62, no. 5 (2014): 1079–86. http://dx.doi.org/10.11118/actaun201462051079.
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The yield of agricultural crops depends on water availability to a great extent. According some projections, the likelihood of stress caused by drought is increasing in future climates expected for the Central Europe. Therefore, in order to manage agro-ecosystems properly, it is necessary to know water demand of particular crops as precisely as possible. Evapotranspiration (ET) is the main part of water balance which takes the water from agro-ecosystems away. The ET consists of evaporation from the soil (E) and transpiration (T) through the stomata of plants. In this study, we investigated ET of spring barley 1-ha field (Domanínek, Czech Republic) measured by Bowen ratio/energy balance method during growing period 2013 (May 8 to July 31). Special focus was dedicated to comparison of barley ET with the reference grass ETo calculated according FAO-56 model, i.e. the determination of barley crop coefficient (Kc). This crop coefficient was subsequently separated into soil evaporation (Ke) and transpiration fraction (Kcb) by adjusting soil and phenological parameters of dual crop coefficient model to minimize the root mean square error between measured and modelled ET. The resulting Kcb of barley was 0.98 during mid-growing period and 0.05 during initial and end periods. According to FAO-56, typical values are 1.10 and 0.15 for Kcb mid and Kcb end, respectively. Modelled and measured ET show satisfactory agreement with root mean square error equal 0.41 mm. Based on the sums of ET and E for the whole growing season of the spring barley, ET partitioning by FAO-56 dual crop coefficient model resulted in E/ET ratio being 0.24.
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Zhao, Liwen, and Wenzhi Zhao. "Canopy transpiration obtained from leaf transpiration, sap flow and FAO-56 dual crop coefficient method." Hydrological Processes 29, no. 13 (January 8, 2015): 2983–93. http://dx.doi.org/10.1002/hyp.10417.
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Bariviera, Guilherme, Rivanildo Dallacort, Paulo S. L. de Freitas, Joao D. Barbieri, and Diego F. Daniel. "Dual crop coefficient for the early-cycle soybean cultivar SoyTech 815 RR." Revista Brasileira de Engenharia Agrícola e Ambiental 24, no. 2 (February 2020): 75–81. http://dx.doi.org/10.1590/1807-1929/agriambi.v24n2p75-81.
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ABSTRACT The objective of this study was to determine the dual crop coefficient of an early-cycle soybean cultivar for the city of Tangará da Serra, MT, Brazil, using high-precision lysimeters. The method used was the dual crop coefficient (dual Kc) of FAO Bulletin 56, constitued by soil evaporation coefficient (Ke), determined by microlysimeters, and by basal crop coefficient (Kcb), determined by weighing lysimeters. Reference evapotranspiration (ETo) was calculated using the Penman-Monteith equation. Soybean sowing and harvesting were performed in the 2015/16 season with spacing of 0.45 m between rows. The reference evapotranspiration (ETo) estimated for the cultivation period was 267.06 mm; the crop evapotranspiration was 323.61 mm throughout its cycle. The Kcb values determined by lysimeters for soybean cultivation were 0.47, 1.15 and 0.89 for the initial, intermediate and final stages, respectively; Ke values at the initial, intermediate and final stages were 0.94, 0.14 and 0.44, respectively.
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Tang, Jiandong, Wenting Han, and Liyuan Zhang. "UAV Multispectral Imagery Combined with the FAO-56 Dual Approach for Maize Evapotranspiration Mapping in the North China Plain." Remote Sensing 11, no. 21 (October 28, 2019): 2519. http://dx.doi.org/10.3390/rs11212519.
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As the key principle of precision farming, variation of actual crop evapotranspiration (ET) within the field serves as the basis for crop management. Although the estimation of evapotranspiration has achieved great progress through the combination of different remote sensing data and the FAO-56 crop coefficient (Kc) method, lack of the accurate crop water stress coefficient (Ks) at different space–time scales still hinder its operational application to farmer practices. This work aims to explore the potential of multispectral images taken from unmanned aerial vehicles (UAVs) for estimating the temporal and spatial variability of Ks under the water stress condition and mapping the variability of field maize ET combined with the FAO-56 Kc model. To search for an optimal estimation method, the performance of several models was compared including models based on Ks either derived from the crop water stress index (CWSI) or calculated by the canopy temperature ratio (Tc ratio), and combined with the basal crop coefficient (Kcb) based on the normalized difference vegetation index (NDVI). Compared with the Ks derived from the Tc ratio, the CWSI-based Ks responded well to water stress and had strong applicability and convenience. The results of the comparison show that ET derived from the Ks-CWSI had a higher correlation with the modified FAO-56 method, with an R2 = 0.81, root mean square error (RMSE) = 0.95 mm/d, and d = 0.94. In contrast, ET derived from the Ks-Tc ratio had a relatively lower correlation with an R2 = 0.68 and RMSE = 1.25 mm/d. To obtain the evapotranspiration status of the whole maize field and formulate reasonable irrigation schedules, the CWSI obtained by a handheld infrared thermometer was inverted by the renormalized difference vegetation index (RDVI) and the transformed chlorophyll absorption in reflectance index (TCARI). Then, the whole map of Ks can be derived from the VIs by the relationship between CWSI and Ks and can be taken as the basic input for ET estimation at the field scale. The final ET results based on multispectral UAV interpolation measurements can well reflect the crop ET status under different irrigation levels, and greatly help to improve irrigation scheduling through more precise management of deficit irrigation.
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Fenner, William, Rivanildo Dallacort, Paulo S. L. de Freitas, Cleonir A. Faria Júnior, Marco A. C. de Carvalho, and Guilherme Bariviera. "Dual crop coefficient of common bean in Tangará da Serra, Mato Grosso." Revista Brasileira de Engenharia Agrícola e Ambiental 20, no. 5 (May 2016): 455–60. http://dx.doi.org/10.1590/1807-1929/agriambi.v20n5p455-460.
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ABSTRACT This study aimed to determine the dual crop coefficient of common bean ( Phaseolus vulgaris L.) for Tangará da Serra-MT, Brazil. The study used the FAO-56 dual kc method, dividing the kc into soil evaporation coefficient (ke), determined in microlysimeters, and basal crop coefficient (kcb), determined in weighing lysimeters. The study was conducted from July 10 (sowing) to October 6, 2014 (harvest), using the common bean cultivar 'BRS Estilo' and a sprinkler irrigation system with a coefficient of uniformity greater than 80%. The total rainfall and irrigation during the crop cycle (84 days) was 524.8 mm; the potential evapotranspiration (ETo) estimated for the period was 327.9 mm, whereas the crop evapotranspiration (ETc) accumulated during the cycle, determined in lysimeters, was equal to 477.5 mm. The kcb values determined for the initial, full development and final stages were 0.32, 1.10 and 0.81, respectively, while for ke, the respective values were 0.85, 0.40 and 0.53.
Dissertations / Theses on the topic "FAO-56 dual crop coefficient method"
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Chen, Shumiao. "Cropping in Urban Ecosystems." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14100.
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The thesis investigates the role played by green roofs in urban areas by reviewing the existing literature and by developing a numerical platform. For this purpose, the FAO-56 dual crop coefficient method (FAO-56 method) has been adopted to evaluate evapotranspiration taking place in some green infrastructure (GI) practices, i.e. green roofs. The Tew Extension was incorporated into the FAO-56 method to achieve more accurate estimates. Modifications were also made to the FAO-56 method with the Tew Extension for the application to agricultural green roofs. The findings relating to the test green roofs’ functions of annual rainfall retention, peak flow rate reduction and runoff delay reveal that green roofs can greatly help mitigate urban runoff volume and rate problems. Regarding the impact on runoff quality, the test green roofs, in most cases, deteriorated the incoming water. The FAO-56 method was applied to urban agriculture and agricultural green roofs, based on which evapotranspiration and irrigation needs of the ten annual crops grown in fields and on rooftops in Australia’s five major cities were estimated. In both field and rooftop cases, different crops planted in the same city resulted in significantly different irrigation needs. In all five cities, all the crops grown on rooftops evapotranspired more water than the crops grown in fields. Nearly in all cases, crops grown on rooftops demanded more irrigation than these crops grown in fields. Most of the water lost through evapotranspiration was transpiration in both field and rooftop cases; however, the percentages of transpiration to evapotranspiration on rooftops were smaller when compared with these in the field case for all the crops in all five cites. In general, a city that is more irrigation water dependent is likely to use a larger portion of total water beneficially. Crops grown on rooftops are likely to take up smaller portions of total delivered water than the same crops grown in fields.
Conference papers on the topic "FAO-56 dual crop coefficient method"
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"Seasonal Kc Curves for Turfgrass Using FAO-56 Dual Crop Coefficient Method." In 2016 ASABE International Meeting. American Society of Agricultural and Biological Engineers, 2016. http://dx.doi.org/10.13031/aim.20162461635.
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Byrdwell, William, and Hari Kiran Kotapati. "Fast chromatography with dual parallel mass spectrometry for lipidomic analysis and regioisomer quantification of pulse lipids." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/kxye7490.
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Pulses are seeds produced from legumes. More specifically, the United Nations Food and Agricultural Organization (FAO) defines pulses as “Leguminosae crops harvested exclusively for their grain, including dry beans, peas and lentilsâ€. This excludes oilseeds, such as soybeans and peanuts. Pulses are well known for their high content of protein and fiber. Most pulses do not contain a lot of oil, and there is not abundant information in the literature on pulse oil triglycerides, or triacylglycerols (TAGs). But pulses are consumed in large quantities in diets around the globe, so even lower amounts of oil in highly consumed pulses means that the composition of the pulse oil is important to the normal diet. We developed a 10-minute method for analysis of pulse oils using fast UHPLC for separation followed by dual parallel mass spectrometry (MS) for detection and quantification of the separated TAGs. Atmospheric pressure photoionization (APPI) MS was used for fat-soluble vitamin (FSV) quantification and for TAG regioisomer quantification and electrospray ionization (ESI) coupled to high-resolution accurate-mass (HRAM) MS was used for lipidomic identification and quantification of TAG molecular species and regioisomers. Calibration standards contained low levels of FSVs, but high levels of TAGs for better quantification of the bulk oil extracted by the Folch method. The TAG calibration standards were comprised of two different regioisomers, representing alternating concentration levels, thereby allowing fragment ratio calibration curves of regioisomers to be constructed along with the normal quantification calibration curves (regioisomer calibration curve within each quantification calibration curve). We found that FSV calibration curves were linear with high correlation coefficients (r2), while TAG calibration curves were best modeled as power functions and gave lower correlation coefficients. The pulse TAGs were rich in polyunsaturated fatty acids, which further adds to the already well-known nutritional benefits of pulses.