Spectral Crop Coefficient Approach for  Estimating Daily Crop Water Use

Abstract. Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (Sorghum bicolor) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h−1 and ±1.0 mm d−1 were obtained at hourly and daily scales, respectively. Total accumulated crop water use during the campaign was underestimated by 5%. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management.

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Temporal and Spatial Changes in Crop Water Use Efficiency in Central Asia from 1960 to 2016

Sustainability ◽

10.3390/su12020572 ◽

2020 ◽

Vol 12 (2) ◽

pp. 572 ◽

Cited By ~ 1

Author(s):

Shuang Liu ◽

Geping Luo ◽

Hao Wang

Keyword(s):

Water Use Efficiency ◽

Central Asia ◽

Water Use ◽

Recovery Period ◽

Crop Coefficient ◽

State Level ◽

Crop Water ◽

Crop Water Use ◽

Use Efficiency ◽

Temporal And Spatial

Water resources among five Central Asian countries are distributed unevenly. Since the collapse of the Soviet Union, the conflict between water and land use has become increasingly serious. Due to limited data, the temporal and spatial characteristics and trends of crop water use efficiency in Central Asia over the past 60 years remain unclear. This paper combines state-level agricultural statistics data and cultivated land data (1975, 2005 and 2015) from remote sensing imagery and calculates crop water use efficiency based on the FAO crop coefficient method. The results are as follows: (1) the development of crop cultivation in Central Asia is divided into an expansion period (1960–1990), a reduction period (1990–2000), and a recovery period (2000–2016); (2) the grain yield in Central Asia increased from 0.9 to 1.9 t/ha during 1960–2016, with Uzbekistan having the highest, reaching 4.2 t/ha in 2016. Cotton yield increased during 1960–1990 and decreased from 1990 to 2016. (3) The grain water use efficiency in Central Asia increased from 0.22 kg/m3 to 0.39 kg/m3 during 1960–2016. The cotton water use efficiency increased from 0.23 kg/m3 to 0.30 kg/m3 during 1960–1990, has decreased since 1990, and is currently close to the 1960s level.

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ESTIMATION OF CROP WATER REQUIREMENT AND CROP COEFFICIENT OF TOMATO CROP USING METEOROLOGICAL DATA IN PAMPAIDA MILLENNIUM VILLAGE, KADUNA STATE, NIGERIA

FUDMA Journal of Sciences ◽

10.33003/fjs-2020-0403-332 ◽

2020 ◽

Vol 4 (3) ◽

pp. 538-546

Author(s):

A. Ahmed ◽

M. A. Oyebode ◽

H. E. Igbadun ◽

Ezekiel Oiganji

Keyword(s):

Soil Moisture ◽

Water Use ◽

Crop Coefficient ◽

Water Requirement ◽

Crop Water Requirement ◽

Growth Stages ◽

Crop Water ◽

Tomato Crop ◽

Crop Water Use ◽

Crop Coefficients

This report presents a study of crop water requirement and crop coefficient (Kc) for Tomato crop cultivated under irrigation in Pampaida Millennium Village Cluster, Ikara Local Government Area of Kaduna State, Nigeria, during the 2009/2010 dry season. A total of 7 tomato farmers were selected out of 45 farmers for the assessment exercise. Water applied per irrigation and soil moisture contents before and after irrigation was monitored throughout the seasons, while Tomato bulbs were harvested at the end of season and weighed. Average crop water use were estimated from the soil moisture content using the gypsum block, while daily reference Evapotranspiration (ETo) were computed from weather data using method Hargreaves equation. Crop coefficient values (Kc) were computed as the ratio of crop water use to ETo. The values of crop coefficients and seasonal crop water requirement per irrigation for different growth stages were determined, the computed *Kc values for different growth stage for the tomato crop grown in the study area was found to be between 0.77-1.15, the initial stage (*Kc =0.81; 20 mm/irrigation), crop development stage (*Kc = 1.09; 28 mm/irrigation), mid-season (*Kc = 1.15; 29 mm/ irrigation) and Late stage (*Kc = 0.77; 19 mm/irrigation), hence the mid-season gave the highest Kc value. However, the crop seasonal water requirement was found to be 386mm, which was within the recommended range. The crop coefficients and seasonal water requirement estimated in this study are reliable and could be used in irrigation design and scheduling for Tomato in the study area.

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Determining irrigation needs of sorghum from two-source energy balance and radiometric temperatures

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-3937-2011 ◽

2011 ◽

Vol 8 (2) ◽

pp. 3937-3960 ◽

Cited By ~ 1

Author(s):

J. M. Sánchez ◽

R. López-Urrea ◽

E. Rubio ◽

V. Caselles

Keyword(s):

Energy Balance ◽

Water Use ◽

Irrigation Management ◽

Crop Coefficient ◽

Balance Model ◽

Crop Water ◽

Phenological Stages ◽

Crop Water Use ◽

Promising Tool ◽

Experimental Campaign

Abstract. Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (Sorghum bicolor) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h−1 and ±1.0 mm d−1 were obtained at hourly and daily scales, respectively. Accumulated crop water use during the campaign resulted 500 mm versus the total 524 mm measured by the lysimeter. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management.

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A parametric crop water use model

Water Resources Research ◽

10.1029/wr017i004p01095 ◽

1981 ◽

Vol 17 (4) ◽

pp. 1095-1108 ◽

Cited By ~ 30

Author(s):

J. E. Burt ◽

J. T. Hayes ◽

P. A. O'Rourke ◽

W. H. Terjung ◽

P. E. Todhunter

Keyword(s):

Water Use ◽

Crop Water ◽

Crop Water Use

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Response of four grain legumes to water stress in south-eastern Queensland. IV. Interaction with sowing arrangement

Australian Journal of Agricultural Research ◽

10.1071/ar9830661 ◽

1983 ◽

Vol 34 (6) ◽

pp. 661 ◽

Cited By ~ 2

Author(s):

RJ Lawn

Keyword(s):

Water Stress ◽

Population Density ◽

Water Use ◽

Spatial Arrangement ◽

Crop Growth ◽

Yield Response ◽

Crop Water ◽

Area Index ◽

Crop Water Use ◽

South Eastern

The effect of spatial arrangement and population density on growth, dry matter production, yield and water use of black gram (Vigna mungo cv. Regur), green gram (V. radiata cv. Berken), cowpea (V. unguiculata CPI 28215) and soybean (Glycine rnax CP126671), under irrigated, rain-fed fallowed and rain-fed double-cropped culture was evaluated at Dalby in south-eastern Queensland. Equidistant spacings increased initial rates of leaf area index (LAI) development and crop water use compared with 1-m rows at the same population densities. In the irrigated and rain-fed fallowed treatments, where more water was available for crop growth, both seed yields and total crop water use were higher in the equidistant spacings. However, in the double-cropped treatment, where water availability was limited, there was no yield difference between rows and equidistant spacings, primarily because initially faster growth in the latter was offset by more severe water stress later in the season. Higher population density also increased initial crop growth rate and water use, particularly in the equidistant spacings. However, there was no significant yield response to density, presumably because subsequent competition for light/ water offset initial effects on growth. Although absolute yield differences existed between legume cultivars within cultural treatments, there were no significant differential responses to either spatial arrangement or population density among these four cultivars.

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21. Crop water use and water conservation benefits from windbreaks

Agriculture Ecosystems & Environment ◽

10.1016/0167-8809(88)90033-3 ◽

1988 ◽

Vol 22-23 ◽

pp. 381-392 ◽

Cited By ~ 9

Author(s):

Gylan L. Dickey

Keyword(s):

Water Use ◽

Water Conservation ◽

Crop Water ◽

Crop Water Use

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A simulation study on the effect of climate change on crop water use and chill unit accumulation

South African Journal of Science ◽

10.17159/sajs.2017/20160119 ◽

2017 ◽

Vol 113 (7/8) ◽

Author(s):

Abiodun A. Ogundeji ◽

Henry Jordaan

Keyword(s):

Climate Change ◽

Water Resources ◽

Water Use ◽

Irrigation System ◽

Future Climate ◽

Crop Water ◽

Crop Water Use ◽

Chill Unit ◽

The Future ◽

The Impact

Climate change and its impact on already scarce water resources are of global importance, but even more so for water scarce countries. Apart from the effect of climate change on water supply, the chill unit requirement of deciduous fruit crops is also expected to be affected. Although research on crop water use has been undertaken, researchers have not taken the future climate into consideration. They also have focused on increasing temperatures but failed to relate temperature to chill unit accumulation, especially in South Africa. With a view of helping farmers to adapt to climate change, in this study we provide information that will assist farmers in their decision-making process for adaptation and in the selection of appropriate cultivars of deciduous fruits. Crop water use and chill unit requirements are modelled for the present and future climate. Results show that, irrespective of the irrigation system employed, climate change has led to increases in crop water use. Water use with the drip irrigation system was lower than with sprinkler irrigation as a result of efficiency differences in the irrigation technologies. It was also confirmed that the accumulated chill units will decrease in the future as a consequence of climate change. In order to remain in production, farmers need to adapt to climate change stress by putting in place water resources and crop management plans. Thus, producers must be furnished with a variety of adaptation or management strategies to overcome the impact of climate change.

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Lower Limits of Crop Water Use in Three Soil Textural Classes

Soil Science Society of America Journal ◽

10.2136/sssaj2011.0248 ◽

2012 ◽

Vol 76 (2) ◽

pp. 607-616 ◽

Cited By ~ 11

Author(s):

Judy A. Tolk ◽

Steven R. Evett

Keyword(s):

Water Use ◽

Crop Water ◽

Crop Water Use ◽

Lower Limits

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CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

Remote Sensing ◽

10.3390/rs10121867 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1867 ◽

Cited By ~ 20

Author(s):

Bruno Aragon ◽

Rasmus Houborg ◽

Kevin Tu ◽

Joshua B. Fisher ◽

Matthew McCabe

Keyword(s):

Remote Sensing ◽

Eddy Covariance ◽

Water Use ◽

Spatial Resolution ◽

Precision Agriculture ◽

High Spatial Resolution ◽

Assessment Tools ◽

Optical Data ◽

Crop Water ◽

Crop Water Use

Remote sensing based estimation of evapotranspiration (ET) provides a direct accounting of the crop water use. However, the use of satellite data has generally required that a compromise between spatial and temporal resolution is made, i.e., one could obtain low spatial resolution data regularly, or high spatial resolution occasionally. As a consequence, this spatiotemporal trade-off has tended to limit the impact of remote sensing for precision agricultural applications. With the recent emergence of constellations of small CubeSat-based satellite systems, these constraints are rapidly being removed, such that daily 3 m resolution optical data are now a reality for earth observation. Such advances provide an opportunity to develop new earth system monitoring and assessment tools. In this manuscript we evaluate the capacity of CubeSats to advance the estimation of ET via application of the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) retrieval model. To take advantage of the high-spatiotemporal resolution afforded by these systems, we have integrated a CubeSat derived leaf area index as a forcing variable into PT-JPL, as well as modified key biophysical model parameters. We evaluate model performance over an irrigated farmland in Saudi Arabia using observations from an eddy covariance tower. Crop water use retrievals were also compared against measured irrigation from an in-line flow meter installed within a center-pivot system. To leverage the high spatial resolution of the CubeSat imagery, PT-JPL retrievals were integrated over the source area of the eddy covariance footprint, to allow an equivalent intercomparison. Apart from offering new precision agricultural insights into farm operations and management, the 3 m resolution ET retrievals were shown to explain 86% of the observed variability and provide a relative RMSE of 32.9% for irrigated maize, comparable to previously reported satellite-based retrievals. An observed underestimation was diagnosed as a possible misrepresentation of the local surface moisture status, highlighting the challenge of high-resolution modeling applications for precision agriculture and informing future research directions. .

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