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S.B. Sterrett, C.P. Savage Jr. and H.E. Hohlt

Tomatoes (Lycopersicon esculentum Mill.) were grown under plastic culture on a Bojac sandy loam soil in 1991, 1992, and 1994 to determine influence of nitrogen rate at planting and water application scheduling by pan evaporation (PAN) on crop yield and fruit size. Marketable yield and percentage of large fruit was significantly increased in 1991, 1992, and 1994 as irrigation application increased from 0.5 to 1.0 or 1.5 PAN (one application per day). Nitrogen applications exceeding 168 kgha–1 resulted in lower yield and reduced fruit size in 1992. In 1994 (late planting followed by hot, dry growing season), yield was increased with increasing N to 213 kgha–1 with 1.0 PAN, but not influenced by N at 1.5 PAN. Residual soil nitrate concentration was increased with reduced irrigation or increased nitrogen application. Nutrient management plans to address non-point source pollution concerns of EPA will need to reflect crop irrigation needs to maintain yield and fruit size while minimizing nitrate accumulation within the soil profile.

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C.D. Stanley and B.K. Harbaugh

A study was conducted to determine the effect of water table depth on water use and tuber yields for subirrigated caladium (Caladium × hortulanum) production. A field-situated drainage lysimeter system was used to control water table depths at 30, 45 and 60 cm (11.8, 17.7, and 23.6 inches). Water use was estimated by accounting for water added or removed (after rain events) to maintain the desired water table depth treatments. In 1998, tuber weights, the number of Jumbo grade tubers, and the production index (tuber value index) of `White Christmas' were greater when plants were grown with the water table maintained at 30 or 45 cm compared to 60 cm. In 1999, tuber weights, the number of Mammoth grade tubers, and the production index, also were greater when plants were grown at water table depths of 30 or 45 cm compared to 60 cm. The average estimated daily water use was 6.6, 5.1, and 3.3 mm (0.26, 0.20, and 0.13 inch) for plants grown at water table depths of 30, 45, and 60 cm, respectively, indicating an inverse relationship with water table depth. While current water management practices in the caladium industry attempt to maintain a 60-cm water table, results from this study indicate that, for subirrigated caladium tuber production, the water table should be maintained in at 30 to 45 cm for maximum production on an organic soil.

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Amy L. Shober, Kimberly A. Moore, Christine Wiese, S. Michele Scheiber, Edward F. Gilman, Maria Paz, Meghan M. Brennan and Sudeep Vyapari

regardless of plant type (e.g., turfgrass, shrubs, trees, and bedding plants) ( South Florida Water Management District, 2008 ; Southwest Florida Water Management District, 2008 ; St. Johns River Water Management District, 2008 ). This 30- to 60-d allowance

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A.L. Shober, K.A. Moore, C. Wiese, S.M. Scheiber, E.F. Gilman and M. Paz

landscapes South Florida Water Management District West Palm Beach, FL Fitzpatrick, G. 1983 Relative water demand in container-grown ornamental plants HortScience 18 760 762 Gilman, E.F. Kane, M.E. 1991 Growth dynamics following planting of cultivars of

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S.M. Scheiber and Richard C. Beeson, Jr

As demands on potable water supplies increase, water management officials are seeking solutions beyond restrictions on irrigation schedules. Demand-based irrigation systems such as tensiometers monitor soil moisture levels then deliver irrigation

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Carolyn DeMoranville, Brian Howes, David White and Daniel Shumaker

Although cranberry production typically requires a low fertilization rate compared to many crops, bog waters are generally discharged through surface water flow directly to streams, ponds or lakes and indirectly to coastal waters. Since discharge is primarily to fresh water bodies, and since such waters are generally phosphorus-limited, P is the fertilizer element of most environmental concern in Massachusetts cranberry production. This study was designed to determine how much P enters and leaves cranberry bog systems on an annual basis, what activities contribute to nutrient releases, and what management changes can reduce P discharges. On a total budget basis, including fertilizer applications as inputs and crop and other biomass (leaves) removal as outputs, the bogs were generally net importers of total N and total P. However, total P in outgoing waters was greater than that in source water. Net TP fluvial output averaged 2.08 kg·ha–1·yr–1 in 2002 (range 0.01 to 4.15); 1.66 kg·ha–1·yr–1 in 2003 (range –0.63 to 3.62) and 1.22 kg·ha–1·yr–1 in 2004 (range –1.24 to 4.30). The primary path of nutrient discharge from the bogs was through surface water. Flooding events were the primary source of total P output from the cranberry bogs. Gross total P export from the cranberry bogs was within the range of that for other reported agricultural land uses but greater than that for forested lands. When fertilizer P input was reduced (20% to 35%) at cranberry bog sites for two consecutive seasons, crop yield was not adversely affected and P discharge was reduced compared to that in the initial (prereduction) year.

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Kent Cushman, Sanjay Shukla, Gregory Hendricks, Thomas Obreza, Fritz Roka and Eugene McAvoy

Florida is one of the leading states in the United States in watermelon production, and on-farm management of nutrients and water is an important issue in the state. A management strategy using higher-than-recommended rates was compared to two strategies using recommended rates. A systems approach was used to define treatments: (HR) high rate of 265 pounds per acre (lb/ac) N, 170 lb/ac P2O5, 459 lb/ac K2O, and soil moisture content of 16% to 20% via seepage irrigation, (RR) recommended rate of 150 lb/ac N, 100 lb/ac P2O5, 150 lb/ac K2O, and soil moisture content of 8% to 12% via seepage irrigation, and (RR-S) equal to RR but irrigation provided by subsurface drip tubing. Large quarter-acre plots were used for each experimental unit. `Tri-X 313' was interplanted with `Mardi Gras' during Spring 2004 and with `SP-1' during Spring 2005 in a RCB design with two replications at the SWFREC in Immokalee. Leaf tissue analyses, petiole sap, and biomass accumulation were recorded each season. Watermelons were harvested at least twice each year and fruit were counted and weighed individually from three subplots within each plot. At least five fruit from each subplot were cut open for internal evaluation. Leaf nitrogen and potassium content for HR was consistently greater than that of RR or RR-S. Yields of HR were 41% to 50% greater than the two RR treatments. Yield was 1089, 704, and 775 hundred-pound units per acre (cwt/ac) in 2004 and 801, 541, and 533 cwt/ac in 2005 for HR, RR, and RR-S, respectively. Soluble solids content and hollowheart incidence were not affected by treatment. Our results indicate HR was more productive than RR or RR-S and may justify the higher inputs associated with this management strategy.

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Ted E. Bilderback

Environmentally compatible production practices are conscious efforts to design and retrofit nursery container growing areas to improve irrigation and nutrient efficiency, and reduce exposure of ground and surface water supplies to contaminated effluent. Irrigation of ornamental crops in containers can be very inefficient, using large quantities of water and fertilizer. Irrigation water and fertilizer use efficiencies are directly related to each other. Improving irrigation efficiency improves nutrient efficiency and reduces water volume and nutrients leaving production beds. Increasing efficiency can be accomplished in many ways. Grouping plant species and container sizes into blocks with similar water requirements improves efficiency. Redesigning overhead sprinkler systems to accomplish uniform distribution across growing beds or replacing worn nozzle orifices can significantly reduce application variability. Low volume/low pressure systems that distribute water directly into containers and apply less water in a specific amount of time compared to overhead sprinkler application, will conserve water. Applying irrigation in short cycles rather than long cycles improves wetting in substrates and conserves electrical energy, water and directly reduces nutrient leaching from containers. Creating microclimates in nurseries to optimize light or reduce container temperatures, disease pressure and crop stress can improve water and nutrient efficacy. Flow of water running off growing areas must be engineered to slow velocity, filter and contain effluent. Strategies should be site-specific. Capture, containment and recycling of irrigation water has been a common practice in many nurseries in the U.S., as a means to provide adequate water supplies. Vegetative filter strips adjacent to beds and containment basins have been installed at nurseries to reduce contaminants in runoff before water enters recycle irrigation supplies. In areas with sandy soils, some nurseries have developed closed systems where drainage channels and collection basins are lined to prevent nitrogen movement from runoff into shallow groundwater.

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Josep Padullés Cubino, Josep Vila Subirós and Carles Barriocanal Lozano

knowledge of the water management practices used in each territorial and socioeconomic context. In the northwestern Mediterranean region, expanding urban areas significantly affect water demand ( Domene and Saurí, 2006 ). Social preferences toward single