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w i n e G R O WIN G CSWA introduces online tool to measure vineyard greenhouse gas emissions ant to know how to calculate greenhouse gas emissions and carbon sequestration in a California vineyard? The California Sustainable Winegrowing Alliance (CSWA) has introduced an online tool based on the DeNitrification and DeComposition (DNDC) model for wine grapes, developed to help winegrowers "measure to manage" to reduce input costs and emissions. The tool is part of CSWA's online Sustainable Winegrowing Self-Assessment and Performance Metrics system, the latter of which measures, manages and tracks energy, water and nitrogen use and greenhouse gas emissions. The tool was developed with partial funding from a three-year California Department of Food & Agriculture Specialty Crop Block Grant. "More than 1,400 researchers and stakeholders worldwide use the DNDC model on over 40 agricultural crops to assess the effects of various management practices on greenhouse gas emissions," says Allison Jordan, CSWA executive director. "By incorporating the DNDC model into the CSWA pro- gram, growers can see more clearly how nitrogen applications and other vineyard practices impact soil-related greenhouse gas emissions. Avoiding excess nitrogen benefits growers' bottom-line, contributes to wine quality and results in better environmental outcomes. "The online Performance Metrics system offers a simplified, user-friendly version of the DNDC tool that enables winegrowers to customize the variables that are the most significant drivers of soil-related greenhouse gas emissions in vineyards. The variables include practices such as vine spacing, type of tillage, use and type of cover crop, amount of compost and amount of nitrogen applied as fertilizer. Results help growers understand relationships between key practices and emissions, and how to improve." For more information, go to sustainablewinegrowing.org/docs/Vineyards_ GHGs_Handout_7.3.13_rev13.lorez.pdf. "Constellation Brands has been working with the new online tool, with the goal of rolling it out to all of our vineyards and wineries in California and Washington to gain a better knowledge of our greenhouse gas emissions," reports Steve Smit, vice president of Grape Management, Constellation Brands. "We feel it is vital to develop metrics to be able to understand where we currently stand and to help identify potential areas of improvement in our path of continuous improvement in sustainability. Having solid metrics will allow us to benchmark these improvements." CSWA worked with Applied GeoSolutions, the University of California, Davis, SureHarvest, the U.S. Department of Agriculture Agricultural Research Service and other project partners for several years to calibrate and validate the DNDC model for winegrapes, assess the influence of vineyard management practices on greenhouse gas emissions and create a user-friendly tool for use by California winegrowers. To begin using the DNDC tool within the Performance Metrics site, visit m etrics.sustainablewinegrowing.org where California participants can log in with their CSWA username and password or request a new username. In the past 10 years, 1,800 vineyard and winery organizations representing more than 70% of California's winegrape acreage and case production have participated in the CSWA Sustainable Winegrowing Program. Visit sustainablewinegrowing.org. If the fuel emissions from tillage passes are included, both conventionally tilled treatments had negative effects on carbon sequestration. Still, the most frequently tilled treatment outperformed the other treatments in fruit yield, probably due to lower competition for water from the cover crop. The results obtained serve as a good comparison to D.S. Kroodsma and C.B. Field's work on carbon sequestration in California agriculture, in which they estimated that vineyards currently sequester 240 kg C ha-1 yr-1, and could sequester above 480 with cessation of tillage.3 Including woody NPP as sequestered carbon, our study found C sequestration under all treatments. However, if we anticipate the decomposition of, or burning of vines at the end of the vineyard's life span, we found only minimum tillage sequestered C, at an averageof 374 kg C ha-1 yr-1. This was because minimum tillage resulted in carbon sequestration into soil. N2O emissions constituted between 6% and 17% of net GWP in the latter case. CH4 oxidation offset about 1% of net GWP. We estimate that with seven years of carbon sequestration into these soils, minimum tillage offset about 35 years of potential GHG emissions from its own management and fertilizer requirements. It is impossible to say at this time when the treatment will stop adding carbon to the soil, but we can expect that the rate will be considerably reduced as the soil carbon pool becomes saturated. What might the future bring for carbon footprints in vineyards? The question is raised whether any other cover crops might successfully sequester carbon under conventional tillage practices. This question stands apart from the use of leguminous cover crops to provide nitrogen to grapevines. But we expect that the two questions will converge as we learn better management strategies for cover crops in vineyards. Likewise, the inclusion of pomace as a soil amendment could affect fertility and soil carbon sequestration. New possibilities may arise for the use of prunings and vineyard wood. Vineyard carbon footprints could be significantly affected if these are used to generate energy, or else converted into products such as biochar, which allow long-term fixation of carbon. PWV Bibliography 1. Chan, A.S.K., Parkin, T.B., 2001 "Effect of land use on methane flux from soil." J. Env. Qual. 30, 786 – 797. 2. IPCC, 2007 Technical Summary 2.5. In: 1, W.G. (Ed.), Fourth Assessment Report: Climate Change 2007. Intergovernmental Panel on Climate Change. 3. Kroodsma, D.A., Field, C.B., 2006 "Carbon sequestration in California agriculture, 1980 – 2000." Ecol. Appl. 16, 1975 –1985. 4. Lal, R., 2004 "Soil carbon sequestration impacts on global climate change and food security." Science (Washington D. C.) 304, 1623 –1627. 5. Liljeroth, E., Schelling, G.C., Van Veen, J.A., 1990 "Influence of Different Application Rates of Nitrogen to Soil on Rhizosphere Bacteria." Netherlands J. Ag. Sci. 38, 255 – 264. 6. Carlisle, E., Smart, R., Bronde, J., Arnold, A. 2009. "Carbon Footprints of Vineyard Operations." Practical Winery & Vineyard September/ October, 15–25. 7. Smart, D.R., Schwass, E., Lakso, A., Morano, L., 2006 "Grapevine rooting patterns: A comprehensive analysis and a review." Am. J. Enol. & Vit. 57, 89–104 W 94 p r acti c al w i ne ry & v i ne yard NOVEMBER 20 13