North Carolina Nutrient Assessment Tool, Version 3.0 contains two field-scale assessment tools: Nitrogen Loss Estimation Worksheet (NLEW) and Phosphorus Loss Assessment Tool (PLAT).
NLEW was developed in response to the Neuse Rules. In August of 1998, the Neuse Rules became law. These rules represented a series of regulations that control point and nonpoint source discharges of nitrogen into the Neuse. As a result of the Local Option that was added to the agricultural best management practice (BMP) rules, producers can join a local strategy rather than implementing mandatory BMPs. The local strategy allows a county to determine where the approved BMPs can be installed to obtain the 30% nitrogen reduction. In addition, the local option provides a few more alternatives to the list of BMPs, such as unfertilized cereal cover crops and no-till corn in the Piedmont, than the standard BMPs. In exchange for this flexibility, however, the rules mandated accountability. The accounting and tracking tool that has been developed to meet the requirements of the Neuse Rules is the Nitrogen Loss Estimation Worksheet (NLEW). In addition, NLEW was adopted by the NC Division of Soil and Water Conservation in 1996 as the method to estimate BMP effects on relative nutrient dynamics for projects funded with Agriculture Cost- Share Program funds. It is also being used in the Tar-Pamlico River Basin.
PLAT was developed in response to the new USDA-Natural Resource Conservation Service (NRCS) nutrient management standard (590). The charge was given that each state must assess phosphorus (P) status during nutrient management planning if animal waste is involved or the field is within an impaired watershed. Three selection strategies were allowed (soil test, environmental test and P index). The North Carolina Phosphorus Loss Assessment Committee chose to use a modified P index assessment method; a unique P assessment method was designed for North Carolina conditions. This P assessment is known as the NC Phosphorus Loss Assessment Tool or PLAT.