Tian Tian, R. Paul Schreiner,* Patricia A. Skinkis, James Osborne, and Elizabeth Tomasino
*USDA-ARS-HCRL, 3420 NW Orchard Ave, Corvallis , OR 97330 (Paul.Schreiner@ars.usda.gov)

The impact of nitrogen (N) additions in the vineyard on vine productivity and wine characteristics was compared to that of winery N additions on wine characteristics in Pinot noir (PN) and Chardonnay (CH).  Five treatments, including no vineyard or winery N addition (control), addition of diammonium phosphate in the winery (+DAP), addition of organic N in the winery (+Org N), and addition of N in the vineyard to the soil (+Soil N) or to the foliage (+Foliar N) were established with four replicates for each variety. The +Foliar N treatment began in 2017, while the other four treatments were evaluated in 2016 and 2017 for CH. For PN, all five treatments began in 2017. In both varieties, +Soil N application increased leaf N status and fruit yeast assimilable nitrogen (YAN) levels, but did not alter yield, leaf area, or vine water status in the first year. Foliar N application also increased fruit YAN in the first year without increasing leaf N or vine growth. Vine growth and yield increased in CH in response to +Soil N in the second year, as did leaf and fruit N status. Root colonization by arbuscular mycorrhizal fungi (AMF) was reduced in both varieties in the +Soil N vines, with greater effect in CH, where N was applied for two years. Vine P status decreased in CH in the second year in concert with lower AMF. Winery N additions boosted must YAN levels to roughly match those of the +Soil N and +Foliar N musts. Must fermentation in CH proceeded more rapidly where N was added in the vineyard or the winery, while fermentation rate in PN was increased only by vineyard N addition. Sensory evaluation of 2016 CH wines showed that +Soil N wines differed from control, +DAP, and +Org N wines.

Funding Support: Oregon Wine Board and USDA-ARS