N2O Emissions in a Merlot Vineyard Under Different Cover Crop Regimes.

While vineyards generally exhibit low nitrous oxide (N2O) emissions as compared to other crops, they account for a large percentage of crop area in California and are therefore an important area of study. Field work was conducted in a vineyard outside of Lodi, CA in a 3 year old Merlot vineyard. N2O emissions under four different treatments of cover crop regimes (both leguminous and non-leguminous) as well as from vine rows were monitored over a complete season. Differences in emission patterns were observed between the vine rows and the cover crop rows, with the vine rows exhibiting greater emissions with the first rainfall event and lower emissions after subsequent events. However, no differences in overall emissions were observed over the course of the season. In order to identify the mechanisms leading to a commonly observed large N2O flux after the first precipitation event of the rainy season, laboratory incubations were performed using undisturbed soil cores.