Chapter 14. New tools to assess nitrogen management for conservation of our biosphere

Authors: Delgado, Jorge; Gagliardi, Paul; SHAFFER, MARVIN - Retired ARS Employee; COVER, HARRIS - Vistronix, Inc; HESKETH, ERIC - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Soil and Water Conservation Society
Publication Type: Book / Chapter
Publication Acceptance Date: 8/24/2010
Publication Date: 12/10/2010
Citation: Delgado, J.A., Gagliardi, P.M., Shaffer, M.J., Cover, H., Hesketh, E. 2010. Chapter 14. New tools to assess nitrogen management for conservation of our biosphere. p. 373-409. In Delgado, J.A. and R.F. Follett (eds). Advances in Nitrogen Management for Water Quality. SWCS, Ankeny, IA.

Interpretive Summary: There are several tools that can be used to assess the effects of management on nitrogen (N) losses to the environment. The Nitrogen Loss and Environmental Assessment Package (NLEAP) is an improved and renamed version of the DOS program that was called the Nitrate Leaching and Economic Analysis Package (NLEAP); see Shaffer et al. (2010). NLEAP-GIS 4.2 is a new, Excel®-driven menu which helps users quickly communicate with Internet databases, convert these databases to a format that is compatible with NLEAP-GIS 4.2, and interact with Geographic Information Systems (GIS). Users of NLEAP-GIS 4.2 may wish to consult the user guide, which provides step-by-step instructions on how to use the model (Delgado et al. 2010). The potential to use a simpler approach to quickly assess the effect of management practices on the risk of nitrogen losses to the environment has been discussed for the last two decades (Follett et al. 1991; Shaffer and Delgado 2002; Delgado et al. 2006). A review of the advantages and disadvantages of the Nitrogen Index was done by Shaffer and Delgado (2002). The Nitrogen Index assesses the risk of nitrogen losses via different pathways. The following are interpretations of the general risk. These interpretations should also be considered for each individual pathway such as leaching, surface and/or atmospheric loss. Even if the general risk (the risk across all pathways) is ranked as Medium or Low, one of the pathways may still show a high risk, so practices that reduce the risk of losses to specific pathways should be considered. Delgado et al. (2008b) defined the new concept of the Nitrogen Trading Tool (NTT) within the context of the N cycle and considered a nitrogen mass balance approach for the cropping systems to ensure that today’s nitrogen management practices will not create problems later on. The tool can quickly compare any given baseline scenario to a new management scenario. They define this trading tool as an economic balance between the new management scenario and the baseline scenario, a balance which functions similarly to a banking operation. A positive balance (NTT-DNLreac) means that a new N management practice increases the savings in reactive N, while a negative number clearly shows that there are no savings in reactive N to trade. Phrased in terms of the bank metaphor, a positive number means that there is “money” (nitrogen) in the bank for trade, while a negative number indicates an empty or overdrawn “account”, and thus no potential for trading.

Technical Abstract: There are several tools that can be used to assess the effects of management on nitrogen (N) losses to the environment. The Nitrogen Loss and Environmental Assessment Package (NLEAP) is an improved and renamed version of the DOS program that was called the Nitrate Leaching and Economic Analysis Package (NLEAP); see Shaffer et al. (2010). NLEAP-GIS 4.2 is a new, Excel®-driven menu which helps users quickly communicate with Internet databases, convert these databases to a format that is compatible with NLEAP-GIS 4.2, and interact with Geographic Information Systems (GIS). Users of NLEAP-GIS 4.2 may wish to consult the user guide, which provides step-by-step instructions on how to use the model (Delgado et al. 2010). The potential to use a simpler approach to quickly assess the effect of management practices on the risk of nitrogen losses to the environment has been discussed for the last two decades (Follett et al. 1991; Shaffer and Delgado 2002; Delgado et al. 2006). A review of the advantages and disadvantages of the Nitrogen Index was done by Shaffer and Delgado (2002). The Nitrogen Index assesses the risk of nitrogen losses via different pathways. The following are interpretations of the general risk. These interpretations should also be considered for each individual pathway such as leaching, surface and/or atmospheric loss. Even if the general risk (the risk across all pathways) is ranked as Medium or Low, one of the pathways may still show a high risk, so practices that reduce the risk of losses to specific pathways should be considered. Delgado et al. (2008b) defined the new concept of the Nitrogen Trading Tool (NTT) within the context of the N cycle and considered a nitrogen mass balance approach for the cropping systems to ensure that today’s nitrogen management practices will not create problems later on. The tool can quickly compare any given baseline scenario to a new management scenario. They define this trading tool as an economic balance between the new management scenario and the baseline scenario, a balance which functions similarly to a banking operation. A positive balance (NTT-DNLreac) means that a new N management practice increases the savings in reactive N, while a negative number clearly shows that there are no savings in reactive N to trade. Phrased in terms of the bank metaphor, a positive number means that there is “money” (nitrogen) in the bank for trade, while a negative number indicates an empty or overdrawn “account”, and thus no potential for trading.