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  • Author or Editor: Dorota Haman x
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A survey was conducted of nursery operators participating in workshops in west-central Florida. The purpose of the survey was to identify the irrigation best management practices (BMPs) adopted by container nurseries in west-central Florida and obtain information regarding emphasis of future extension educational programs. Workshops were conducted in Hillsborough County, Fla., and Manatee County, Fla., and participation was voluntary. Respondents were asked about BMPs used in the nurseries according to the irrigation system used and it was found that the majority of the nurseries relied on well water as the primary source for irrigation. While 69% of the nurseries monitored uniformity of microirrigation systems, only 35% monitored uniformity of overhead irrigation systems. Thirty-four percent of the nurseries collected irrigation or rain runoff and 9% knew the water holding capacity of their substrate. Most of the nurseries grouped plants by irrigation requirements (74%) and grouped container sizes by irrigation requirements (69%). The survey indicates that many BMPs are not widely adopted by nurseries in west-central Florida. The information from this survey can be used as a guide to focus the efforts of university extension educational programs to achieve greater adoption of BMPs.

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Evaporation pans continue to be used extensively throughout the world to measure free-surface water evaporation (Epan) and to estimate evapotranspiration for irrigation scheduling and water management for agronomic and horticultural crops. Epan is also being used extensively to estimate evaporation rates from lakes, wetlands, rivers, reservoirs, and other water bodies for management of wildlife and ecological habitat. A reliable method is needed to estimate missing daily Epan data. Determination of a reliable method for the estimation of Epan would also be useful in modeling of crop growth, and hydrological and ecological systems. Five methods [Penman (Penman, 1948), Kohler-Nordenson-Fox (KNF) (Kohler et al., 1955), Christiansen (Christiansen, 1968), Priestley-Taylor (PT) (Priestley and Taylor, 1972), and Linacre (Linacre, 1977)] for estimating Epan were compared with the historical (23-year) measured daily values to determine the suc- cess of accurate and consistent Epan estimations under humid climatic conditions in Florida. The root mean square error (RMSE) was used as the criteria to judge the accuracy and reliability of a given method. An RMSE value of <0.5 mm·d-1 (0.02 inches/d) between the measured and estimated Epan was considered as an acceptable error for daily estimations. The standard deviation (sd) values, and percent error (%E) between the estimated and measured values were also considered in the performance evaluations. Performance evaluations of the Epan estimates of the methods were made on a daily, monthly, and annual basis. Results indicated that the KNF method provided the best Epan estimations. The Linacre method yielded the poorest estimates. The second, third, and fourth best methods were the Penman, PT, and Christiansen, respectively. The RMSE and sd of Epan estimates were lowest when using KNF method. The mean value of the %E of daily, monthly, and annual estimations were 27%, 27%, and 26% for Christiansen; 6%, 6%, and 4% for KNF; 33%, 32%, and 26% for Linacre; 24%, 24%, and 21% for PT; and 19%, 17%, and 11% for Penman methods, respectively. The weekly, monthly, and annual total of Epan estimates from KNF method were also compared to the measured values of the two selected years of data (1981 and 1983). The annual rainfall totals were significantly lower than the 23-year mean in 1981, and higher in 1983. The %Es of weekly, monthly, and annual total Epan estimates were 9%, 9%, and -1% in 1981; and 11%, 5%, and 4% in 1983, respectively. The KNF method underestimated Epan in 1981 (dry year) and the underestimations were higher in summer months. The underestimations in a dry year, especially in summer months, might be due to the fact that the sensible heat advection is not effectively accounted for in the KNF equation causing underestimations of Epan. Overall results indicated that the KNF method should be the first choice, among the methods tested, for estimating daily Epan for irrigation scheduling and for estimating the missing Epan data in humid areas.

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Nonweighing drainage lysimeters were used to measure seasonal water use of mature ‘Emerald’ southern highbush blueberry (SHB; Vaccinium corymbosum interspecific hybrid) plants grown in pine bark beds and in pine bark amended soil in north central Florida. In the absence of rain, irrigation was applied daily with microsprinklers at ≈120% to 175% of reference evapotranspiration as either single or split applications. Leachate was collected and its volume determined from each lysimeter at 6- to 10-day intervals throughout the study. Water use, expressed as L/plant, was calculated as the difference between the amount of irrigation/rain added to lysimeters and the amount of leachate collected from lysimeters during each measurement period. Average daily water use was calculated for monthly intervals beginning in Apr. 2010 and ending in Sept. 2012. Water use increased rapidly during spring through the final stages of fruit ripening and harvest (May) with peak water use occurring during mid to late summer (July, August, and September). Plants grown in pine bark beds used more water than plants in pine bark amended soil during Apr., May, and Dec. 2010, Feb. 2011, and Mar. 2012, but there were no differences during the periods of highest water use. No differences in water use were observed between single or split-application irrigation treatments. Monthly averages for daily water use during the 30-month period ranged from ≈1.75 L/plant in January to ≈8.0 L/plant in mid to late summer. Mean monthly crop coefficient values during the 30-month period ranged from 0.44 in February to 0.86 in September. Canopy volume, yield, and mean berry weight were unaffected by soil or irrigation treatments.

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