Maryland Nutrient Trading Tool: Estimating Creditable On-farm Nutrient Reductions

摘要

Water quality trading is gaining traction in a number of watersheds around the world. It is a market-based approach that works alongside water quality regulation to improve water quality. In 2008, the State of Maryland developed its nutrient trading policy to create offset mechanisms for new and expanding nutrient discharges in the Chesapeake Bay watershed. Maryland's nutrient trading policy allows trades between regulated point sources and agricultural nonpoint sources. In order to facilitate implementation of Maryland's nutrient trading program, the Maryland Department of Agriculture (MDA) worked with the World Resources Institute (WRI) (which had previously developed NutrientNet) and the Texas Institute for Applied Environmental Research, Tarleton State University (TIAER) (which had developed the national Nutrient Tracking Tool or NTT) to create a unified tool that would:1) Estimate on-farm nutrient reductions, determine baseline compliance, and calculate credit generation potential;2) Registerand track the lifecycle of each credit; and3) Provide an online marketplace where buyers and sellers could exchange credits and manage individual accounts.This presentation will focus on the functionality of the on-farm nutrient reduction estimation tool. Typically, estimating nutrient reductionsfrom nonpoint sources has been problematic within the context of a water quality trading program as no simple estimation tools have been developed and site-specific monitoring is unrealistic. The Maryland Nutrient Trading Tool, developed by MDA, WRI andTIAER, is the first on-farm nutrient estimation tool to use a dynamic, biophysical model as the basis of its calculations. This tool incorporates a dynamic map, the NTT model, and state policy considerations in order to estimate the amount of nutrient creditable nutrient reductions that can be generated through various best management practices implemented on the farm.