Event Related N2O Emissions From a Traditionally Managed Vineyard in California, USA.

With the passage of the California Global Warming Solutions Act of 2006 (AB32), California has begun an earnest mission to reduce greenhouses gas (GHG) emissions to 1990 levels by 2020. Of the three major GHG’s (CO₂, N₂O, and CH₄), N₂O has the greatest radiative forcing, with almost 300 times the radiative forcing potential of CO₂, and it is well known that cultivated soils emit substantial quantities of N₂O through agricultural related activities. Since California has such a large agricultural industry, there is an urgent need to understand and potentially mitigate N₂O emissions from California agriculture. However, very little data exists on annual N₂O fluxes, especially within perennial cropping systems, as it is very erratic, expensive to measure, and highly dependent on management techniques. The aim of this project was to quantify annual N₂O fluxes in a wine grape vineyard under traditional management following specific management events (e.g. tillage, cover crop incorporation, irrigation and fertilization). Using static closed chambers, N₂O emissions were measured in a wine grape vineyard in Arbuckle, California consisting of two treatments: mowed and incorporated cover crop and mowed only cover crop. Throughout the season we measured the effects of standard management practices (irrigation, fertilization, mowing, and tilling, etc.) and environmental controls (NO₃, NH₄, soil moisture, temperature, precipitation, and soil type) on N₂O emission rates. Preliminary data has shown that N₂O fluxes are highly dependent on vineyard floor and vine management practices as well as environmental controls. This data may be used to eventually calibrate and validate biogeochemical models used to predict GHG emissions from agricultural crops specific to California conditions and may be used to contribute to the quantification of regional GHG budgets.