Landscape-level variation in greenhouse gas emissions in vineyards of central California
Abstract
Greenhouse gas emissions from agricultural soils can differ greatly across the landscape depending on soil type, landscape formation and management, making the implementation of mitigation practices challenging. In our study, we evaluated the carbon dioxide and nitrous oxide emissions from vineyard soils across a broad landscape in the Lodi Wine-grape District representing three soil types of different geologic history and under varying conventional management systems in the Central Valley of California. Soils of the District vary in space as a result of the depositional history of the parent materials from which the soils formed and subsequent weathering. The nature of the deposition of these materials has resulted in systematic patterns of soils in space. We sampled the following soils from this soil sequence over the larger landscape: 1) Slightly weathered granitic alluvium with low clay content located on the southern side of the district; 2) Intermediately weathered soils derived from granitic alluvium with high clay content located on the northern side of the district; and, 3) Highly weathered soils derived from metavolcanic and metasedimentary alluvium with intermediate clay content and rocky soils located on the eastern side of the district. The climate is Mediterranean with cool, moist winters and hot, dry summers. Initial results indicated that under wet conditions, the soils had similar carbon dioxide emissions with little variation between management or landscape formation. However, carbon dioxide emissions were typically higher in the alley than in the vine row. Nitrous oxide emissions were more variable in the higher clay soils as compared to sandier soils (0-180 g N/ha/day and 0-20 g N/ha/day, respectively). Nitrous oxide emissions were similar from the soil in the alley and vine row. We expect to see similar variability for carbon dioxide emissions under drier conditions later in the summer, but predict that it will differ by landscape position during pulse events (i.e., precipitation, irrigation, tillage) and that the magnitude of the differences will lessen with increased soil moisture and cooler temperatures in the winter. Though management such as tilling and irrigation can cause pulses of greenhouse gases from vineyard soils, our initial findings suggest that on a landscape level over longer time periods, differences between the soils and geologic history may be a better predictor of greenhouse gas emissions than management alone.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.B11A0461B
- Keywords:
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- 0414 BIOGEOSCIENCES / Biogeochemical cycles;
- processes;
- and modeling