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Methodology for Quantifying Nitrous Oxide (N2O) Emissions Reductions through Reduced Use of Nitrogen Fertilizer on Agricultural Crops

The ACR Methodology for Quantifying Nitrous Oxide (N2O) Emissions Reductions from Reduced Use of Nitrogen Fertilizer on Agricultural Crops details requirements for quantifying greenhouse gas (GHG) emission reductions by reducing the amount of nitrogen used to fertilize crops. The methodology was jointly developed by Michigan State University (MSU) and the Electric Power Research Institute (EPRI).

The methodology is applicable to the Agriculture, Forestry and Other Land Use (AFOLU) sector, and is specific to Agricultural Land Management (ALM) project activities. The scope of this methodology is limited to on-farm reductions in N fertilizer rate associated with the management of N-containing synthetic and organic fertilizers that reduce net N2O emissions from annual or perennial cropping systems. Emissions reductions and crediting for project activities occur by reducing the N fertilizer rate during the crediting period, when compared to the baseline (pre-project) period.

During a project crediting period, adherence to Best Management Practices (BMPs) as they relate to the application of synthetic and organic N fertilizer at the cropping site is required. These BMPs are related to N fertilizer formulation (or N content of organic additions) and dates and methods of application. Project Proponents shall describe and justify in the GHG Project Plan how relevant BMPs have been adhered to.

Three project categories are eligible under this version of the methodology:

  1. Category 1: Proposed projects located in the U.S. North Central Region (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin) that involve corn in row-crop systems such as continuous corn and rotations of corn-soybean or corn-soybean-wheat. Projects in this category use Method 1, an IPCC Tier 2-equivalent relationship between N2O emissions and N application rates developed by MSU, to calculate N2O emissions reductions. Only the corn component of a rotation is eligible for crediting. Projects located within the NCR boundary that involve crops other than corn, including crops in rotation with corn, are eligible under Categories 2 and 3.
  2. Category 2: Proposed projects located worldwide that include fertilized agricultural crops may submit empirical data published (or accepted to be published) in peer-reviewed scientific journals documenting that the use of the Tier 1 emission factor (EF1 = 1.0% [0.01]; IPCC 2006) is conservative for calculating N2O emissions at the project site(s). ACR will engage experts to review the data.
  3. Category 3: Proposed projects located worldwide that include fertilized agricultural crops may use a new project-specific emission factor if project proponents demonstrate using empirical data published (or accepted to be published) in peer-reviewed scientific journals that the use of a new Tier 2 emissions factor is conservative for calculating N2O emissions at the project site(s). ACR will engage experts to review the data.

During a project crediting period, projects initially accepted for inclusion in Category 2 can be re-assigned to Category 3, should new data become available. A retroactive crediting mechanism is provided to incentivize the collection of N2O emissions data and the development of emissions factors compatible with IPCC Tier 2 methodologies.

Process documentation:

  • Public comments and responses
  • Peer review comments and responses
  • Millar, N., Robertson, G.P., Grace, P.R., Gehl, R.J., and Hoben, J.P. (2010). Nitrogen Fertilizer Management for Nitrous Oxide (N2O) Mitigation in Intensive Corn (Maize) Production: An Emissions Reduction Protocol for US Midwest Agriculture. Mitigation and Adaptation Strategies for Global Change 15:185–204.
  • Hoben JP, Gehl RJ, Millar N, Grace PR, Robertson GP (2011). Non-linear nitrous oxide (N2O) response to nitrogen fertilizer in on-farm corn crops of the US Midwest. Global Change Biology 17:1140–1152.
  • Projects using this methodology must comply with all requirements of the ACR Standard, submit a GHG Project Plan for certification by ACR, and secure independent validation and verification by an ACR-approved third-party verifier.

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