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Said A. Hamido, Kelly T. Morgan and Davie M. Kadyampakeni

Evapotranspiration (ET) is a dominating factor in the water cycle for most agricultural crops including citrus and plays a critical role in irrigation management ( Bates et al., 2008 ; Castel et al., 1987 ; Jia et al., 2007 ; Morgan, 1992

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J.A. Doty, W.S. Braunworth Jr., S. Tan, P.B. Lombard and R.D. William

Evapotranspiration (ET) of three perennial ryegrass (Lolium perenne L.) cultivars and one cultivar each of colonial bentgrass (Agrostis tenuis L.) and tall fescue (Festuca arundinacea L.) was measured in the field. Soil water depletion was measured with a neutron probe. Under minimal maintenance (i.e., no irrigation and infrequent mowing), ET was not significantly different for five perennial grasses. All grasses used more water than the bare-ground treatment. Soil water uptake was greatest in the upper soil layer (O to 25 cm) and decreased with depth. Few differences in water uptake were noted among grasses within each soil layer.

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Jeffrey G. Williamson, Luis Mejia, Bradley Ferguson, Paul Miller and Dorota Z. Haman

( Vaccinium ) irrigation exist, but few studies report actual water use or crop evapotranspiration (ETc) for blueberry, especially in the southeastern United States where SHB on heavily amended soils predominate. Dourte et al. (2010) studied plant water use

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Jeff B. Million and T.H. Yeager

affect evapotranspiration (ET) rates (e.g., plant growth, pruning, spacing) can change rapidly compared with microirrigated plants grown in large containers. Furthermore, the capture of sprinkler irrigation water can be greatly affected by the plant

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Xuelian Jiang, Yueling Zhao, Rui Wang and Sheng Zhao

evapotranspiration ( ET ) deficit. Other studies have found positive linear relationships between tomato yield and seasonal ET ( Chen et al., 2013 ; Kuscu et al., 2014 ; Zheng et al., 2013 ). To describe the effects of both irrigation level and application

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David R. Bryla and Robert G. Linderman

arranged in a split-plot design and included three irrigation systems (overhead sprinkler, microspray, and drip) as main plots and three irrigation levels [50%, 100%, and 150% of the estimated crop evapotranspiration requirements (ET c )] as subplots. Each

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Gail R. Nonnecke and Henry G. Taber

The purpose of this project was to investigate the use of evapotranspiration (ET) as a guideline for trickle irrigation timing in field-grown day-neutral `Tristar' strawberry. Proper management of trickle irrigation would allow optimum yields and quality with minimum water inputs. A randomized complete block field design with four replications was used at the ISU Horticulture Station in central Iowa. Irrigation treatments were based on % of ET and number of applications per week. The four treatments included: 30, 60, and 90 % of ET applied once per week (1X) and 30% of ET applied 3 times per week (3X). Total yield data (kg of fruit per season) indicated the 30% of ET (3X) treated plants yielded 15% more fruit than the 30% of ET (1X) plants. Berry number was 14% greater from plants receiving the 30% of ET (3X) treatment than from those receiving the 30% of ET (1X) treatment. Average berry weights for the entire growing season were similar among all treatments.

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Giovanni Piccinni, Thomas Gerik, Evelyn Steglich, Daniel Leskovar, Jonghan Ko, Thomas Marek and Terry Howell

Improving irrigation water management for crop production is becoming increasingly important in South Texas as the water supplies shrink and competition with urban centers in the region grows. Crop simulators and crop evapotranspiration (ET) are appealing methods for estimating crop water use and irrigation requirements because of the low investment in time and dollars required by on-site (in-field) measurement of soil and/or crop water status. We compared the effectiveness of the crop simulator and Crop-ET approaches estimating the crop water use for irrigation scheduling of spinach. In-ground weighing lysimeters were used to measure real-time spinach water use during the growing season. We related the water use of the spinach crop to a well-watered reference grass crop to determine crop coefficients (Kc) to assist in predicting accurate crop needs using available meteorological data. In addition, we ran several simulations of CropMan to evaluate the best management for growing spinach under limited water availability. Results show the possibility of saving about 61 to 74 million m3 of water per year in the 36,500 ha of irrigated farms of the Edwards aquifer region if proper irrigation management techniques are implemented in conjunction with the newly developed decision support systems. We discuss the implications of the use of these technologies for improving the effectiveness of irrigation and for reducing irrigation water requirements in South Texas.

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David R. Bryla, Thomas J. Trout and James E. Ayars

crops are needed. A dependable method to estimate crop water requirements is a simple procedure whereby water lost by soil evaporation and plant transpiration, referred to collectively as crop evapotranspiration (ET c ), is calculated by multiplying

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Esmaeil Fallahi, Bahar Fallahi and Michael J. Kiester

this treatment, the trees were irrigated once a week at the full rate of evapotranspiration (ETc) for apple starting in 2002. During the period of this study (2008–11), ETc values for fully mature trees were used. Method for ETc calculation is described