Simplified Water Requirement Calculators for Fruits and Vegetables

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.

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Water requirement and crop coefficients of sorghum in Apodi Plateau

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v25n10p684-688 ◽

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.

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Lysimeter-based Crop Coefficients for Young Highbush Blueberries

HortScience ◽

10.21273/hortsci.31.5.819 ◽

1996 ◽

Vol 31 (5) ◽

pp. 819-822 ◽

Cited By ~ 7

Author(s):

Craig A. Storlie ◽

Paul Eck

Keyword(s):

Water Use ◽

Canopy Cover ◽

Crop Coefficient ◽

Average Diameter ◽

Vaccinium Corymbosum ◽

Average Height ◽

Design Characteristics ◽

Highbush Blueberries ◽

June July ◽

Crop Coefficients

Inexpensive weighing lysimeters ($1475/unit) were constructed for measuring evapotranspiration of young highbush blueberries (Vaccinium corymbosum L.). The use of a single load cell and other design characteristics decreased lysimeter measurement accuracy but minimized lysimeter construction costs. Measurement error was within ±3%. Crop coefficient (CC) curves for 5- and 6-year-old `Bluecrop' highbush blueberry plants in their third and fourth year of production were generated using reference evapotranspiration and crop water use data from the 1991 and 1992 growing seasons. The CC increased during leaf expansion and flowering in the spring to its maximum value of about 0.19 in 1991 and 0.27 in 1992 and remained near these values until leaves began senescing in the fall. Water use on sunny days during June, July, and August ranged from (liters/bush each day) 3.5 to 4.0 in 1991 and 4.0 to 4.5 in 1992. During the second year of the study, plants had an average height of 0.9 m, an average diameter of 0.9 m, and covered 18% of the total cultivated area. The maximum calculated CC was equal to 1.5 times the measured canopy cover percentage.

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254 Study of Regular and High Applications of Water with Drip Irrigation in Small `Manzanillo' Olives

HortScience ◽

10.21273/hortsci.34.3.486a ◽

1999 ◽

Vol 34 (3) ◽

pp. 486A-486

Author(s):

Adán Fimbres Fontes ◽

Raúl Leonel Grijalva Contreras ◽

Manuel de Jesus Valenzuela Ruiz

Keyword(s):

Drip Irrigation ◽

Sandy Loam ◽

Crop Coefficient ◽

Sandy Loam Soil ◽

Pan Evaporation ◽

Water Requirements ◽

Loam Soil ◽

Optimum Water

The area of olives in the region of Caborca has been increasing in the last years to 4500 ha. Olives in other regions do not need the application of water, at Caborca evaporation is greater than rainfall. Because of that situation, an experiment was conducted in 1998 to determine the optimum water requirements and the crop coefficient for `Manzanillo' olives (2 years of planted) under drip irrigation and microsprinkler in a sandy loam soil. The results indicated no difference between treatments (50%, 75%, and 100% of ET estimated in a pan evaporation). The water applied to each treatment was 13.32, 19.98, and 26.64 cm.

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

Geoscientific Model Development ◽

10.5194/gmd-8-1233-2015 ◽

2015 ◽

Vol 8 (4) ◽

pp. 1233-1244 ◽

Cited By ~ 11

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.

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

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-4933-2015 ◽

2015 ◽

Vol 12 (5) ◽

pp. 4933-4963 ◽

Cited By ~ 1

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

Transactions of the ASABE ◽

10.13031/trans.13933 ◽

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.

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Standard single and basal crop coefficients for vegetable crops, an update of FAO56 crop water requirements approach

Agricultural Water Management ◽

10.1016/j.agwat.2020.106196 ◽

2021 ◽

Vol 243 ◽

pp. 106196

Author(s):

L.S. Pereira ◽

P. Paredes ◽

R. López-Urrea ◽

D.J. Hunsaker ◽

M. Mota ◽

...

Keyword(s):

Vegetable Crops ◽

Crop Water ◽

Water Requirements ◽

Crop Water Requirements ◽

Crop Coefficients

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

Irriga ◽

10.15809/irriga.2006v11n1p26-35 ◽

2006 ◽

Vol 11 (1) ◽

pp. 26-35 ◽

Cited By ~ 2

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

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ESTIMATING WATER REQUIREMENTS OF LANDSCAPE PLANTINGS

HortScience ◽

10.21273/hortsci.27.12.1263f ◽

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.

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Water Requirements of Drip-Irrigated Maize (Zea mays L.) with Plastic Mulching in Heilongjiang, Northeast China

Transactions of the ASABE ◽

10.13031/trans.13521 ◽

2019 ◽

Vol 62 (6) ◽

pp. 1697-1704

Author(s):

Songjun Han ◽

Di Xu ◽

Yingduo Yu ◽

Jiandong Wang ◽

Yanqun Zhang

Keyword(s):

Drip Irrigation ◽

Northeast China ◽

Crop Coefficient ◽

Temporal Variations ◽

Water Requirement ◽

Irrigation Requirement ◽

Large Area ◽

Plastic Mulch ◽

Water Requirements ◽

Plastic Mulching

Abstract. A large area of rainfed maize ( L.) is planned to be replaced by maize under drip irrigation with plastic mulching (MDI) in Heilongjiang, northeast China, through a “water-saving and grain-increasing action” project. However, knowledge is lacking on the water requirements of maize under MDI. On the basis of a locally developed crop coefficient for a site, the spatial and temporal variations in crop water requirement (ETc) and net irrigation requirement (Nir) of maize under MDI in Heilongjiang were evaluated. The average ETc and Nir of maize under MDI in the period from 1960 to 2017 for 29 meteorological stations were 279 to 388 mm and 73 to 198 mm, respectively, which are approximately 10% and 15% lower than the ETc and Nir under conventional surface irrigation (NSI). The differences in ETc and Nir between the two irrigation technologies are significant in the southwestern region, which demonstrates that the intensive planning of MDI in the southwest is justified. The gross irrigation requirement of maize under MDI in an excessive drought year is estimated as 437 million m3 for the project, which is 137 million m3 less than the irrigation requirement using NSI.HighlightsAverage ETc and Nir of maize under MDI are approximately 10% and 15% lower than those under NSI.The differences in ETc and Nir are significant in the southwestern region of Heilongjiang.The estimated gross irrigation requirement of maize under MDI is much less than that under NSI. Keywords: Crop coefficient, Drip irrigation, Maize, Northeastern China, Plastic mulch, Water requirement.

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