A model for estimating soil moisture changes as an aid to irrigation scheduling and crop water-use studies: II. Field test of the model

1996 ◽  
Vol 12 (3) ◽  
pp. 129-133 ◽  
Author(s):  
R.J. Bailey ◽  
S.J. Groves ◽  
E. Spackman
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Field Test ◽  
Irrigation Scheduling ◽  
Crop Water ◽  
Crop Water Use ◽  
Use Studies

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.

EVALUATION OF LATENT EVAPORATION ESTIMATES AND THEIR CONVERSION TO POTENTIAL EVAPORATION

1971 ◽  
Vol 51 (4) ◽  
pp. 255-266 ◽  
Author(s):  
W. BAIER
Keyword(s):  
Water Use ◽  
Irrigation Scheduling ◽  
Type Model ◽  
Climatic Data ◽  
Crop Water ◽  
Crop Water Use ◽  
Air Temperatures ◽  
Crop Development ◽  
Irrigated Crops ◽  
Consumptive Water

Daily and monthly latent evaporation (LE) estimates obtained from an earlier-described regression-type model are compared with estimates from Penman’s (PE) and Thornthwaite’s (PET) techniques. Penman’s PE was selected as a control. Daily PE estimates were more closely related to LE than to PET estimates, as seen from the coefficients of determination (100 CD) of 52 and 21%, respectively. Similarly, variations of monthly PE means were more closely associated with variations of monthly LE means (65%) than with PET means (45%). Both the LE and PET models use the same standard climatic data as input. The improvement of 31% for the daily values and 20% for the monthly means results from using maximum and minimum air temperatures separately in the LE model, instead of mean air temperature as in the PET technique. The least bias in PE as derived from converted LE estimates was obtained by a factor of 0.0094 cm/cm3 (0.0037 in./cm3). However, a review of literature on ratios of consumptive water use by irrigated crops to LE measurements suggested a factor in the order of 0.0086 cm/cm3 (0.0034 in./cm3). This factor has been successfully employed in irrigation scheduling and water budgeting experiments. The discrepancy could result from the consumptive crop water use for part of the growing season being less than Penman’s PE as computed in this study. Although eventually seasonally adjusted conversion factors based on crop development phases are preferred, the findings warrant the use of the LE model in various climates for estimating either PE, by applying 0.0094 cm/cm3 (0.0037 in./cm3), or seasonal consumptive crop water use, by applying 0.0086 cm/cm3 (0.0034 in./cm3).

scholarly journals Crop Water Use and Irrigation Scheduling Guide for North Florida

EDIS ◽  
2020 ◽  
Vol 2020 (6) ◽  
Author(s):  
Vivek Sharma ◽  
Charles Barrett ◽  
De Broughton ◽  
Thomas Obreza
Keyword(s):  
Water Use ◽  
Irrigation Schedule ◽  
Irrigation Scheduling ◽  
Growth Stages ◽  
Crop Water ◽  
Leaching Potential ◽  
Crop Water Use ◽  
Crop Water Demand ◽  
Crop Growth Stages ◽  
The Right

Effective irrigation scheduling enables the irrigator to apply the right amount of water at the right time to meet the crop water demand. This 19-page guide presents information on average daily and weekly crop water use and crop growth stages for twelve north Florida crops that can be used to help schedule irrigation. This will allow a grower to develop a realistic irrigation schedule that minimizes plant water stress, saves water, and reduces nutrient leaching potential. Written by Vivek Sharma, Charles Barrett, De Broughton, and Thomas Obreza, and published by the UF/IFAS Department of Soil and Water Sciences, revised December 2020.

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 EFFECT OF IRRIGATION REGIMES ON YIELD AND WATER USE EFFICIENCY OF EXTRA-EARLY MAIZE VARIETY IN KANO RIVER IRRIGATION PROJECT

2020 ◽  
Vol 4 (3) ◽  
pp. 292-299
Author(s):  
Mubarak Lawal ◽  
Muyideen Abubakar Oyebode ◽  
Jamilu Suleiman
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Irrigation Water ◽  
Block Design ◽  
Irrigation Scheduling ◽  
Yield Reduction ◽  
Crop Water ◽  
Crop Water Use ◽  
Irrigation Regimes ◽  
Use Efficiency

A field experiment was conducted to evaluate the effect of irrigation regimes on yield and water use efficiency of maize crop (Zea Mays L.; SAMMAZ 29) under different irrigation scheduling. Randomized Complete Block Design (RCBD) was used and the experiment consisted of three levels of irrigation water application depth of 100%, 75% and 50% replacement of Total Available Water Capacity (TAWC) and three irrigation intervals of 7, 10 and 13 days replicated three times. Irrigation water was applied into each of 0.75 m × 90 m furrow using siphon tube of 7.5 cm diameter and 200 cm length. The results showed that the highest average irrigation water use efficiency was at I10D75% with 0.71 kg/m3 while the least was at I13D50% with 0.41 kg/m3. The highest average crop water use efficiency (CWUE) was at I10D75% with 0.79 kg/m3 while the least was at I13D75% with 0.56 kg/m3. The highest average maize yield was at I7D100% with 3580 kg/ha while the least was at I13D50% with 1200 kg/ha. The study established that irrigation after every 10 days interval with 75% replacement of TAWC using furrow irrigation of 90 m lengths produced the highest crop water use efficiency, thus saving about 48.3% of irrigation water (amounting to 329 mm) with reference to control (I7D100%) which causes a yield reduction of about 19% (amounting to 680 kg/ha). This efficient water usage saved cost and also helps to address the problem of high water table of the study area.

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