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.
Simple vs. Complex: Implications of Lags in Pollution Delivery for Efficient Load Allocation and Design of Water-quality Trading Programs
