The most immediate issue for California growers is that coalition permits under the Central Valley Regional Water Board’s Irrigated Lands Program have been expanded to include groundwater. Already, monitoring has found nitrates in excess of drinking water limits at some groundwater locations in the Central Valley, including the Tulare Basin. A report on this issue is due to the state legislature in early 2012, and it is likely additional scrutiny will result.

Under the proposed expanded Irrigated Lands Program, any grower who irrigates in the Central Valley will need to become a coalition member. Individual growers will be expected to review their fertilizer practices and develop programs to reduce potential impacts from fertilizer inputs.  Exact details of what will be required where nitrates in groundwater are a known issue are still being negotiated.  One idea that has been put forward is the requirement for nutrient plans to be supervised by licensed professionals, such as certified crop advisors (CCAs).

On the air quality side, the State Air Resources Board (ARB) is currently required to reduce greenhouse gas emissions in California. Nitrous oxide, which is 300 times more potent a greenhouse gas than CO2, is formed when applied nitrogen reacts with bacteria in the soil. ARB had considered regulating fertilizers as a greenhouse gas precursor, but now has indicated it is looking for voluntary reductions in ag N2O emissions to help it achieve reductions in emissions required under state law.  The Almond Board is currently funding research to develop data on actual N2O emissions in almond production. Data to date indicate that N2O emissions from almonds are less than initially estimated by the regulators. In addition, the Almond Board is funding research on possible carbon offsets for the industry.

These are just two of the most pressing regulatory issues related to nitrogen use facing all California growers. Over the next few months, we will look in more detail at new studies helping fine-tune sampling protocols and application of nitrogen, both fossil-fuel–based and organic. The goal in both research and outreach is to develop ways for growers to hit the “Four Rs” of application to meet tree demand, optimize crop yield and avoid offsite movement of applied fertilizers.

To see research projects on nitrogen use in almonds, go to and choose air quality and water quality projects.