Making sense of cosmic-ray soil moisture measurements and eddy covariance data with regard to crop water use and field water balance

2018 ◽  
Vol 204 ◽  
pp. 271-280 ◽  
Author(s):  
Enli Wang ◽  
Chris J. Smith ◽  
Ben C.T. Macdonald ◽  
James R. Hunt ◽  
Hongtao Xing ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Balance ◽  
Eddy Covariance ◽  
Water Use ◽  
Cosmic Ray ◽  
Crop Water ◽  
Crop Water Use ◽  
Making Sense ◽  
Field Water Balance

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

2018 ◽  
Vol 10 (12) ◽  
pp. 1867 ◽  
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. .

scholarly journals High-Throughput Phenotyping of Crop Water Use Efficiency via Multispectral Drone Imagery and a Daily Soil Water Balance Model

2018 ◽  
Vol 10 (11) ◽  
pp. 1682 ◽  
Author(s):  
Kelly Thorp ◽  
Alison Thompson ◽  
Sara Harders ◽  
Andrew French ◽  
Richard Ward
Keyword(s):  
Water Balance ◽  
Water Use Efficiency ◽  
Soil Water ◽  
Water Use ◽  
High Throughput ◽  
Soil Water Balance ◽  
Balance Model ◽  
Crop Water ◽  
Crop Water Use ◽  
Use Efficiency

Improvement of crop water use efficiency (CWUE), defined as crop yield per volume of water used, is an important goal for both crop management and breeding. While many technologies have been developed for measuring crop water use in crop management studies, rarely have these techniques been applied at the scale of breeding plots. The objective was to develop a high-throughput methodology for quantifying water use in a cotton breeding trial at Maricopa, AZ, USA in 2016 and 2017, using evapotranspiration (ET) measurements from a co-located irrigation management trial to evaluate the approach. Approximately weekly overflights with an unmanned aerial system provided multispectral imagery from which plot-level fractional vegetation cover ( f c ) was computed. The f c data were used to drive a daily ET-based soil water balance model for seasonal crop water use quantification. A mixed model statistical analysis demonstrated that differences in ET and CWUE could be discriminated among eight cotton varieties ( p < 0 . 05 ), which were sown at two planting dates and managed with four irrigation levels. The results permitted breeders to identify cotton varieties with more favorable water use characteristics and higher CWUE, indicating that the methodology could become a useful tool for breeding selection.

scholarly journals Evaluation of Evapotranspiration from Eddy Covariance Using Large Weighing Lysimeters

Agronomy ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 99 ◽  
Author(s):  
Jerry Moorhead ◽  
Gary Marek ◽  
Prasanna Gowda ◽  
Xiaomao Lin ◽  
Paul Colaizzi ◽  
...  
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Water Use ◽  
Growing Season ◽  
Irrigation Scheduling ◽  
Error Rates ◽  
Energy Balance Closure ◽  
Crop Water ◽  
Crop Water Use ◽  
Hourly Data

Evapotranspiration (ET) is an important component in the water budget and used extensively in water resources management such as water planning and irrigation scheduling. In semi-arid regions, irrigation is used to supplement limited and erratic growing season rainfall to meet crop water demand. Although lysimetery is considered the most accurate method for crop water use measurements, high-precision weighing lysimeters are expensive to build and operate. Alternatively, other measurement systems such as eddy covariance (EC) are being used to estimate crop water use. However, due to numerous explicit and implicit assumptions in the EC method, an energy balance closure problem is widely acknowledged. In this study, three EC systems were installed in a field containing a large weighing lysimeter at heights of 2.5, 4.5, and 8.5 m. Sensible heat flux (H) and ET from each EC system were evaluated against the lysimeter. Energy balance closure ranged from 64% to 67% for the three sensor heights. Results showed that all three EC systems underestimated H and consequently overestimated ET; however, the underestimation of H was greater in magnitude than the overestimation of ET. Analysis showed accuracy of ET was greater than energy balance closure with error rates of 20%–30% for half-hourly values. Further analysis of error rates throughout the growing season showed that energy balance closure and ET accuracy were greatest early in the season and larger error was found after plants reached their maximum height. Therefore, large errors associated with increased biomass may indicate unaccounted-for energy stored in the plant canopy as one source of error. Summing the half-hourly data to a daily time-step drastically reduced error in ET to 10%–15%, indicating that EC has potential for use in agricultural water management.

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

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.

A parametric crop water use model

1981 ◽  
Vol 17 (4) ◽  
pp. 1095-1108 ◽  
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

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

1983 ◽  
Vol 34 (6) ◽  
pp. 661 ◽  
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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