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John C. Majsztrik and John D. Lea-Cox

Restoration efforts in the Chesapeake Bay recently intensified with the 2010 introduction of federal total maximum daily load (TMDL) limits for all 92 bay watershed segments. These regulations have specific, binding consequences if any of the six states or the District of Columbia fail to meet interim goals, including loss of federal dollars for various programs and increasing regulation of point sources, if non-point source (agricultural and urban) nutrient reduction goals are not met in the watershed. As part of the effort to better understand and account for non-point sources of pollution in the watershed, a team of agricultural experts from across the bay region was recently assembled, including the nursery industry. The goal of this panel was to inform stakeholders and policymakers about the inputs and management practices used across all Bay states. To increase both the precision and accuracy of loading rate estimates, more precise information should guide future iterations of the Chesapeake Bay model. A more accurate accounting of land area by operation type (e.g., greenhouse, container, and field) is a primary issue for the nursery and greenhouse industry, because the current Chesapeake Bay model relies on USDA agricultural census data, which does not separate container and field production, which have very different nutrient and irrigation practices. Field operations also typically account for a higher percentage of production area in each state, which may skew model results. This is very important because the type of operation (field, container-nursery, or greenhouse operation) has a significant impact on plant density, types of fertilizer used, and application rates, which combine with irrigation and water management practices to affect potential nutrient runoff. It is also important to represent a variety of implemented best management practices (BMPs) in the Chesapeake Bay model such as vegetated buffer strips, sediment ponds, controlled-release fertilizer, and accurately assess how these mitigate both nutrient and sediment runoff from individual operations. There may also be opportunities for growers who have implemented BMPs such as low-phosphorus slow-release fertilizers (SRF), precision irrigation, etc., to gain additional revenue through nutrient trading. Although there are currently some questions about how nutrient trading will work, this could provide additional incentives for further implementation of BMPs by both ornamental and other agricultural growers. It is possible that the TMDL process currently being implemented throughout the Chesapeake Bay will be used as a remediation process for other impaired estuarine water bodies, which have similar water-use regulations and issues. The lessons learned about the Chesapeake Bay model in general, and for the nursery and greenhouse industry in particular, will likely provide guidance for how we can be proactive in reducing environmental impacts and protect the economic viability of ornamental growers in the future.

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Luther C. Carson and Monica Ozores-Hampton

This publication summarizes the factors influencing controlled-release fertilizer (CRF) nutrient release, CRF placement, CRF rate, and CRF application timing for the two major seepage-irrigated vegetable production systems (plasticulture and open-bed) in Florida. One of several best management practices for vegetable production, CRF helps growers achieve total maximum daily loads (TMDLs) established in Florida under the Federal Clean Water Act. Several factors intrinsic to CRF and to the vegetable production systems affect CRF nutrient release, making implementation of CRF fertility programs challenging. Increasing or decreasing soil temperature increases or decreases nutrient release from CRF. Soil moisture required for uninhibited plant growth is within the soil moisture range for optimum CRF nutrient release. CRF substrate affects nutrient release rate, which is inversely related to coating thickness and granule size. Soil microbes, soil texture, and soil pH do not influence nutrient release rate. Field placement of CRFs in seepage-irrigated, plasticulture, and open-bed production should be in the bottom mix at bed formation and soil incorporated or banded at planting, respectively. In plasticulture production systems, soil fumigation and delayed planting for continuous harvest may add a 14- to 21-day lag period between fertilization and planting, which along with different season lengths will influence CRF release length selected by growers. Using a hybrid fertilizer system in plasticulture production or incorporating CRF at planting in open-bed production allows for up to a 25% reduction in the nitrogen (N) rate needed.

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Robert F. Polomski, Douglas G. Bielenberg, Ted Whitwell, Milton D. Taylor, William C. Bridges, and Stephen J. Klaine

1972 Federal Clean Water Act are enforced ( Beeson et al., 2004 ). Environmental concerns and regulatory pressure to reduce nutrient loadings in surface waters have led to the EPA enforcing its Total Maximum Daily Load (TMDL) program for all watersheds

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Robert F. Polomski, Douglas G. Bielenberg, Ted Whitwell, Milton D. Taylor, William C. Bridges, and Stephen J. Klaine

Water Act, which mandates that all states implement a Total Maximum Daily Load (TMDL) program for all watersheds and bodies of water ( U.S. EPA, 2000 ). A TMDL is the maximum amount of pollutant that a water body can receive from point and nonpoint

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Chris Wilson, Joseph Albano, Miguel Mozdzen, and Catherine Riiska

developing total maximum daily loads (TMDLs) for NO 3 -N and other nutrients in many watersheds throughout the United States. Ultimately, these TMDLs will limit the amount of NO 3 -N that can be discharged into off-site water bodies. For nurseries that

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Nicholas A. Pershey, Bert M. Cregg, Jeffrey A. Andresen, and R. Thomas Fernandez

PO 4 3− -P may promote cyanobacteria blooms that can damage sensitive ecosystems ( Anonymous, 2008 ). In addition to regulating concentration, total maximum daily load (TMDL) standards have been developed on a case-specific basis to set a maximum rate

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Carolyn DeMoranville

maximum daily load (TMDL) limits set. The TMDL process identifies the acceptable load and divides it among the lands that drain into the water body. When cranberry farms are within the regulated area for a TMDL, even if cranberry farming is not the major

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Rachel Mack, James S. Owen, Alex X. Niemiera, and Joyce Latimer

). To ensure human safety and protect the environment, the Environmental Protection Agency issued a total maximum daily load (TMDL) establishing limits to the amount of sediment and nutrients that can be discharged into tributaries of the Chesapeake Bay

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Sarah A. White

is uncertain. In the two most recent cases in which regulations were imposed in an effort to protect water resources, the Florida numeric nutrient criterion used concentration-based end points, whereas the Chesapeake Bay used total maximum daily loads

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John C. Majsztrik, Elizabeth W. Price, and Dennis M. King

%, respectively (see Table 4 ). Results and discussion Monetizing potential environmental benefits: chesapeake bay region illustration. A number of regions such as Florida, California and the Chesapeake Bay are implementing total maximum daily load (TMDL