A new draft of a scoping plan for meeting long-term greenhouse gas (GHG) reductions in California includes new greenhouse gas targets specifically for agriculture.

The scoping plan provides a roadmap for meeting required GHG reductions under Assembly Bill 32 (AB 32) for eight key economic areas, including energy, transportation, water and agriculture. AB 32 was passed into law in 2006 and requires California to reduce its greenhouse gas emissions by 25 percent (back to 1990 levels) by 2020, and even further (to 20 percent of 1990 levels) by the year 2050.

The three GHGs of concern in agriculture are carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄).

For the 2020 goal, agriculture was not expected to directly contribute to GHG reductions, but to reach the 2050 goal, the plan proposes that greenhouse gas targets be set specifically for agriculture.

Meeting Goals

That means programs will likely be developed for agriculture in areas the California Air Resources Board (ARB) expects GHG reductions can be achieved, such as reductions in N₂O emissions from fertilizers, improved water-pumping efficiencies, methane capture from dairies and other sources. Yet to be seen is whether these reductions will be achieved by mandating particular practices, by providing incentives to integrate certain practices, or simply by taxing to encourage desired GHG reductions.

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Over the next two years, an interagency panel, consisting of representatives from ARB, Department of Food and Agriculture (CDFA), Department of Pesticide Regulation, Department of Water Resources and others, will determine both the goals and how those goals for agriculture should be met.

At the same time, ARB still wants to see agriculture provide offset credits to economic sectors that are regulated under the current cap-and-trade system. The offset credit system allows an individual who voluntarily reduces their greenhouse gas emissions in some way to then sell those credits to businesses that are required to reduce their greenhouse gas emissions.

Carbon Market Challenge

Based on research done by the Almond Board, current carbon sequestration/emission-reduction possibilities for almonds include incorporating chipped prunings to increase and sequester soil carbon; changes in nitrogen management to reduce N₂O emissions, such as avoiding water-saturated soils, applying smaller and more frequent rates of N through fertigation and choices of nitrogen; irrigation; and other factors.

Initially, the ag sector had expected to earn money for offset credits under AB 32. The system has since become extremely complicated and expensive both in terms of the criteria for being considered an offset credit and the verification procedures. However, beginning in 2015, additional sectors will fall under cap-and-trade, which will likely increase the demand for offset credits and their value.

There is also a voluntary carbon market that may be easier for growers to navigate. The many requirements are less stringent than offset credits under ARB’s regulations. The value of the credit is likely to be less, but so is the cost to show the greenhouse gas reduction is real.

The California rice industry has stepped up to be the first to try to navigate this maze. A voluntary “rice protocol” with a focus on methane emission reductions has been drafted and was opened for public comment in mid-March. ARB hopes to complete the process of approving the protocol by this fall to allow rice growers to sign up in early 2015.

Almond Emissions/Sequestration

A meeting hosted by the Almond Board’s Environmental Committee last October highlighted some of the key research in the area of greenhouse gas emissions and sequestration in almonds, as well as opportunities and issues related to agricultural carbon offsets. The research builds on more than 40 years of Almond Board–funded research, and is beginning to allow us to model which practices reduce GHG or increase emissions through all stages of almond propagation, production, harvesting, hulling and shelling.

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Meeting attendees from outside agencies, including CDFA and the Environmental Defense Fund, expressed astonishment at the amount of data the Almond Board had accrued that was available to populate the latest research. Among the current projects:

Almond tree growth modeling. A project by Extension pomology specialist Dr. Ted DeJong at UC Davis uses almond tree growth modeling to gather better data on carbon allocation in trees. Dovetailing on previous spur-growth research to build a 3-D “virtual tree,” DeJong can then simulate functions and biomass growth of almond trees. This will provide data for things like estimating the total biomass being removed in an orchard that could be available for bioenergy, or for determining the addition of soil carbon from chipping.

Emissions Data

Emissions data and fertigation. Work by Professor David Smart’s lab at UC Davis looks at how N₂O emission and nitrate leaching rates are affected by changes in fertigation regimes. Among other things, the lab’s research is providing data on nitrous oxide emissions under different irrigation systems, different N sources and different frequencies of applications. Having real N₂O emissions data rather than modeled data for an irrigated tree crop is rare. With the help of Almond Board of California funds, there is now data from three different locations.

DNDC model for almonds. The first draft of an almond-specific denitrification- decomposition (DNDC) model has been developed by Dr. Bill Salas and coworkers at Applied GeoSolutions. The DNDC model accounts for carbon and nitrogen use and emissions from the soil and plants. ARB has determined that the DNDC model is the most appropriate model to account for both carbon and nitrogen in production agricultural systems. A DNDC model for rice forms the basis for its draft protocol.

Almond life cycle assessment. Environmental engineering professor Dr. Alissa Kendall at UC Davis is researching greenhouse gas offset opportunities based on an almond life cycle assessment (LCA). The life cycle assessment research is providing a better understanding of the energy use and GHG emissions/sequestration related to propagating, growing, harvesting and hulling/shelling almonds over the 25-year life span of an almond orchard.

The LCA results indicate that most of the energy and GHG emissions in almonds are associated with water and nitrogen fertilizer. However, the use of almond by-products, such as prunings and tree removals, or feeding almond hulls to cattle, can substantially reduce the total greenhouse gas emissions from 25 years of growing an almond orchard.

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