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Johannes Scholberg, Kelly Morgan, Lincoln Zotarelli, Eric Simonne, and Michael Dukes

Most strategies used to determine crop N fertilizer recommendations do not address potential environmental issues associated with agricul-tural production. Thus, a more holistic approach is required to reduce N loading associated with vegetable crops production on soils that are prone to N leaching. By linking fertilizer N uptake efficiency (FUE) with irrigation management, root interception capacity, and N uptake dynamics, we aim to improve FUE. Nitrogen uptake for peppers, tomato, potato, and sweet corn followed a logistic N accumulation patterns. Up to 80-85% of N uptake occurred between 4 to 7 weeks (sweet corn) vs. 6 to 12 weeks (other crops), while N uptake during initial growth and crop maturation was relatively low. Maximum daily N accumulation rates occurred at 5 weeks (sweet corn) vs. 8-10 weeks (other crops) and maximum daily N uptake rates were 4-8 kg N/ha. Overall FUE for most vegetables may range between 23% and 71%, depending on production practices, soil type, and environmental conditions. Maximum root interception capacity was typically attained 3 to 5 weeks prior to crop maturity. It is concluded that, during initial growth, root interception may the most limiting factor for efficient N use. Although recent uptake studies have shown that FUE may be highest toward the end of the growing season, this may not coincide with the greatest crop demand for N, which occurs during the onset of the linear growth phase. As a result, yield responses to N applied later in the season may be limited. Integration of these results into best management practices and expert systems for vegetable production can minimize the externalities associated with commercial vegetable production on vulnerable soils in the southeastern United States.

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Christine M. Worthington and Chad M. Hutchinson

The St. Johns River has been identified by the state of Florida as a priority water body in need of restoration. Best Management Practices were evaluated for potato (Solanum tuberosum L. `Atlantic') production in the Tri-County Agricultural Area to reduce nitrate run-off from about 9,300 ha in production. Objectives of this study were 1) determine the influence of soluble and controlled release fertilizer (CRF) and timing of leaching irrigation on nitrate leaching and 2) compare yield and quality of the potato crop fertilized with either a soluble or controlled release nitrogen fertilizer in a seepage irrigated production system. The experiment was a split-split plot with four replications. Main plots were irrigation events (0, 2, 4, 8, and 12 weeks after planting, (WAP)), nitrogen source and rates included (ammonium nitrate (AN) 224 kg·ha–1 or controlled release fertilizer (CRF) 196 kg·ha–1). About 7.6 cm of water was applied at each irrigation event and surface water runoff collected. CRF decreased NO3-N loading by an average of 35%, 28%, and 32% compared to AN fertilizer during the 2, 8, and 12 WAP irrigation events, respectively, compared to AN. Plants in CRF treatments had significantly higher total and marketable tuber yields (30 and 25 t·ha–1) compared to plants in AN treatments (27 and 23 t·ha–1), respectively. Plants in the CRF treatments also had significantly higher total and marketable yields in 2005 (28 and 23 t·ha–1) compared to plants in AN treatments (25 and 21 t·ha–1), respectively. CRF was an effective alternative to conventional soluble forms of fertilizer maintaining yields and protecting natural resources from nonpoint source pollution.

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Julie Newman, Kristine Gilbert, Ben Faber, Donald Merhaut, Laosheng Wu, Jay Gan, and Richard Evans

Nursery growers must implement “Best Management Practices” (BMPs) to mitigate runoff and leaching of pollutants. However, there is little data on the effectiveness of BMPs, and further research is needed. Growers require training to minimize runoff and capital to comply with evolving regulations. We collected irrigation efficiency data at 26 nursery sites using catch cans. Uniformity value was calculated as: DU = 100 × (Average of the “Low Quarter”/Average of All Measurements). Results showed that one-third of the nurseries had irrigation uniformities below 67%, and only one nursery exceeded 82%. Continuous flow monitoring at 10-minute intervals was conducted at three nursery sites to determine daily and monthly variation. One hundred samples of the runoff were taken four times at each nursery and analyzed for nitrate, chloride, and sulfate. We developed a 29-page checklist of BMPs to reduce runoff, which we used to survey 53 growers in Ventura County. After completing the survey, 20 growers applied for funds from a 1.2 million dollar cost-share program that we initiated. This program provides funds to implement improved technologies to reduce runoff and/or conserve water; funds were awarded to 18 nurseries. We are collecting monitoring data from each cooperating nursery implementing improvements. These data measure the number of BMPs used by growers, provide a current “snapshot” of the industry, and document the effectiveness of future BMP implementation. We offer on-farm consulting, and conducted eight water quality/irrigation educational programs—four in Spanish. We elevated grower awareness concerning regulations and options for reducing runoff, and the data will be useful in evaluating future improvements.

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Joan Bradshaw and Monica Ozores-Hampton

In 1988, the Florida Legislature passed the Solid Waste Management Act that affected the solid waste disposal practices of every county in the state. With legislation directly affecting the industry, organic recyclers and Florida Department of Environmental Protection (FDEP) regulators recognized a need to establish a professional organization that could serve as a unified industry voice, and foster high standards and ethics in the business of recycling and reuse of organic materials. In December 1994, a meeting was held to discuss the formulation of a Florida organic recycling association which became known as the Florida Organics Recyclers Association (FORA). FORA's first major contribution to the industry was the development of a recycling best management practice manual for yard trash in 1996. The second major project undertaken by FORA was a food waste diversion project which sought to promote an increase in food waste recovery and reuse. In Spring 1999, FORA became the organic division of Recycling Florida Today (RFT) further unifying recycling efforts within the State of Florida. In an attempt to address mounting concerns regarding industry marketing and promotional needs, RFT/FORA developed an organic recycling facility directory for the State of Florida in Spring 2000. Most recently RFT/FORA developed an organic recycling facility operator training course outline to assist the FDEP in identifying industry training needs. From its modest beginnings in 1994, to future joint programming efforts with the University of Florida's Florida Organic Recycling Center for Excellence (FORCE), RFT/FORA continues to emerge as a viable conduit of educational information for public and private agencies relative to organic recycling in Florida.

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Jeff B. Million and T.H. Yeager

A goal of irrigation best management practices in container nurseries is to conserve water while maintaining optimal plant growth and quality. A web-based, container irrigation management program (CIRRIG) was developed to automatically provide daily irrigation run times for sprinkler-irrigated crops in container nurseries. The program estimates evapotranspiration rates based on weather uploaded from a weather station located on-site and plant production conditions monitored in each zone and adjusts irrigation run times based on irrigation application rate, the plant’s irrigation-capturing ability (for sprinkler irrigation), desired leaching fraction, and irrigation system uniformity. For this project we interfaced CIRRIG output with a programmable logic controller (PLC) to automatically irrigate a sprinkler-irrigated crop at a container nursery in Florida. Sweet viburnum (Viburnum odoratissimum) in 10-inch-diameter containers were grown by the nursery for 24 weeks in adjacent irrigation zones, one controlled automatically using CIRRIG and the other by the nursery’s traditional practice of manually turning on and off irrigation. Water use was monitored with flowmeters and plant growth by measuring plant size and shoot dry weight periodically throughout the trial. Plant growth was not different (P < 0.05) because of irrigation practice. CIRRIG reduced water use during the study period by 21% (42 vs. 53 inches) compared with the nursery’s irrigation practice. An assessment of the water-saving benefits of making daily adjustments to irrigation run times based on weather including rain indicated savings of 25% and 40% compared with biweekly adjustments with and without automatic rain cutoff, respectively. This trial demonstrated that CIRRIG coupled with an on-site weather station and a computer-controlled irrigation system can be used to manage irrigation while conserving water in a container nursery.

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David R. Sandrock, Ray D. William, and Anita N. Azarenko

Nitrogen (N) management in container nurseries is part of a complex system. Working within this system, nursery owners, managers and employees routinely make N management decisions that have consequences for the immediate nursery environment (e.g., plant growth, yield, disease susceptibility, water quality) as well as areas beyond nursery boundaries (e.g., surface and groundwater quality, public perception). Research approaches often address parts of the system associated with the immediate nursery environment and purpose. As a result, best management practices that contribute to greater N use efficiency have been developed. Research approaches that consider the whole system reveal novel relationships and patterns that identify areas for future research and may direct future management decisions. To investigate N management from a whole system perspective, a group of nursery managers from Oregon and scientists from Oregon State University met three times between 2001 and 2003. Growers drew their N management systems and identified components, relationships and feedback loops using an ActionGram technique. From this information, researchers developed Group-based On-site Active Learning (GOAL). GOAL combines Action-Grams and the Adaptive Cycle at container nursery sites. In this case, N flow and management in container production systems served as the topic of active learning. Managers and employees from four wholesale container nurseries evaluated the GOAL exercise. After completing GOAL, 94% of participants indicated that they learned a new idea or concept about N cycling in their container nursery. Of those, 100% gained new ideas and concepts from peers and colleagues present at the meeting. In addition, 60% gained new ideas and concepts from researchers and 60% developed their own ideas and concepts. GOAL is a learning tool that provides a simple, convenient, interactive format for investigating complex systems.

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R.S. Mylavarapu

Recommendations made for nutrient applications have traditionally focused on economic yield and quality. However, present-day testing procedures and recommendations are required to simultaneously ensure economical and environmental sustainability of agricultural production systems. A soil test is a calibrated index relating crop response to applied nutrients. Any application rate devoid of an economical response in yield or quality is deemed unnecessary. Therefore, a soil test becomes the first step in any nutrient best management practice (BMP) development, implementation, and monitoring activity. Certain significant areas in Florida, such as calcareous soils, require development of calibrated soil tests rather urgently. Nutrient sufficiency of perennial crops and deficiency diagnostics can be gauged through in-season plant tissue testing. Nutrient delivery for correcting the deficiency through foliar sprays is not always effective, and may require multiple applications. Spectral reflectance methods show significant promise as an alternative to traditional wet chemistry analyses with regard to ease, costs, and speed with wider range of applications, including natural resources. Additional research is needed to develop this technology for field-scale applications. Current research is focusing on environmental nutrient management to include nutrient sources, application rates and timing, nutrient uptake efficiency, retention capacity of soils, estimating and minimizing nutrient losses to the environment, etc. Nutrient loss assessments tools such as the Florida phosphorus (P) index and bahia (Paspalum notatum) and citrus (Citrus spp.) tests for P are now being made possible in Florida through integration of soil and tissue testing methods. Development and improvements of such analytical methods and tools specific to Florida to include other nutrients, heavy metals, soil capacity, and ecosensitive regions, is vital to ensure sustainability to the state's tourism, agriculture, and urban-rural balance.

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Thomas H. Yeager

The nursery industry in Broward County, Fla., had to choose between partaking in the resolution needed to achieve 10 ppb total phosphorus discharged to the Everglades or face regulation. The industry decided to pursue the proactive route and implement best management practices (BMPs). Teams of industry personnel were formed to develop the content of the Florida Container Nursery BMP Guide that contained the following chapters: 1) nursery layout, 2) container substrate and planting practices, 3) fertilization management, 4) container substrate nutrient monitoring, 5) irrigation water quality, 6) irrigation application, 7) irrigation uniformity, 8) erosion control and runoff water management, 9) pesticide management, and 10) waste management. Each team was to determine the content of their chapter, based on cultural practices producers were currently using, or could be using, which would minimize or reduce surface water movement of phosphorus from the nursery to adjacent water. Cultural practices, brought forth after a consensus was achieved by each team in concert with governmental agencies, associations, and allied industries, were meshed with research information, or the “best” information available from academic sources to ensure that the resolutions or BMPs that were written would contribute to resolving the confl ict (i.e., elevated total phosphorus in canal waters). Consensus development is a new challenge for most academicians but it is important because unbiased and science-based knowledge is needed to assist in BMP development. Furthermore, consensus of those directly and indirectly involved in the nursery industry helps facilitate the use of BMPs. Once the Florida Container Nursery BMP Guide is adopted by rule under the statutory authority of the Florida Department of Agriculture and Consumer Services, nursery operators voluntarily using the BMPs and keeping appropriate records will receive a waiver of liability from cleanup costs associated with contaminated ground or surface water, and be presumed to be in compliance with state water quality standards.

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Sudeep Vyapari, Edmund L. Thralls, and Michele S. Scheiber

A study was conducted to evaluate establishment of root-bound vs. nonroot-bound container-grown Plumbago auriculata Lam. in a landscape. A total of 144 plants were transplanted from #1 containers in a rain-out shelter at Mid-Florida Research and Education Center, Apopka, Fla., in June 2004. The field soil type was amended with composted yard waste. The three treatment types used for the study were: 1) root-bound plants; 2) root-bound plants with a vertical slice made through the root ball at a 90° angle; and 3) nonroot-bound plants. To evaluate the effect of these three treatments during the course of establishment period, harvesting was done once every 2 weeks. Data on growth indices (height × width × width), shoot dry weight, root dry weight, and length of the longest root were recorded. The experimental design was a completely randomized design consisting of three treatments, 12 harvest dates (days after planting), and four replicates per harvest date. Plants were maintained according to the best management practices recommended by the UF/IFAS, and were irrigated once a day using microirrigation. Experimental data were analyzed for significance of correlation among variables using SAS version 9.1. Results of the correlation and regression analysis indicated that the increase in the shoot dry weights (g), root dry weights (g), growth indices (m3), and root: shoot ratio had significant relationship with the harvest dates. Correlation among harvest dates and shoot dry weight, root dry weight, or growth indices was found to be positive. However, results of the study indicated that as the number of days after planting increased, the root to shoot ratio decreased.

Open access

William D. Afton, Kathryn K. Fontenot, Jeff S. Kuehny, and Carl E. Motsenbocker

Forty-five cultivars of lettuce (Lactuca sativa) were field-grown using best management practices at the Louisiana State University Agricultural Center (LSU AgCenter) Botanic Gardens in Baton Rouge during the Fall 2011 and Fall 2012 seasons. Recommended cultivars were selected for commercial production in Louisiana based on fresh weight and lettuce size (width and height). Nitrate (NO3 ) concentration was analyzed for each cultivar, as lettuces are known to accumulate and concentrate NO3 , and were then compared with the U.S. Environmental Protection Agency’s (EPA) oral reference dose (RfD—the EPA’s maximum acceptable oral dose of a toxic substance) of 1.6 mg NO3-nitrogen (N) per kilogram body weight per day. Recommended butterhead cultivars were Caliente and Harmony (21.6 and 13.9 ppm NO3 , respectively); recommended green-leaf cultivars were Salad Bowl and Tango (10.6 and 4.6 ppm NO3 , respectively); recommended red-leaf cultivars were Red Salad Bowl, Red Sails, and New Red Fire (15.2, 15.4, and 24.0 ppm NO3 , respectively). The only recommended romaine cultivar was Green Towers (11.2 ppm NO3 ), and recommended crisphead cultivars included Raider and Ithaca (17.6 and 14.9 ppm NO3 , respectively). Of the highest yielding cultivars, New Red Fire accumulated the greatest NO3 concentration: 24.0 ppm in both years 1 and 2. The NO3 concentration is less than the levels of concern for both men and women 20 to 74 years old, 3.9% of the RfD for men and 4.59% of the RfD for women.