Soil, foliar, and juice nitrogen application: influence on fruit and wine for Chardonel grown in Virginia

Abstract

Nitrogen (N) is applied in the vineyard or the winery in wine production systems. The influence of different routes of N application is not well understood. Thus, we evaluated the effects of vineyard-applied soil and foliar N on fruit chemistry, fermentation and wine sensory characteristics in the interspecific hybrid Chardonel, in Virginia, USA. For three years, three levels of soil N and two levels of foliar N were applied. Yeast assimilable nitrogen (YAN) and amino acids, soluble solids, pH, TA, yield, berry weight, cluster weight and pruning weight were determined. Wines were made from all field treatments in 2022, and in 2023, winery N addition was overlaid on the control and high vineyard N levels to compare the effects of vineyard- vs. winery-applied N. Wines were subjected to chemical and sensory evaluation.

Vineyard-applied N led to higher YAN, with great impact of foliar vs. soil N. YAN ranged from 128 to 255 mg/L, 132 to 270 mg/L, and 59 to 175 mg/L in 2021, 2022, and 2023. The most prevalent amino acids were proline, glutamine, alanine and arginine. Growing season had the greatest impact on individual amino acids, followed by soil, then foliar N. No effects on yield, berry weight, pH, or TA, and minimal effects on soluble solids, cluster weight, and pruning weight were observed. For 2022, sensory differences were observed among wines, but differences were not explained by the field treatments alone. Moderate soil N associated with fruit-forward wines, while foliar N did not associate with consistent outcomes. Sensory differences were also observed among the 2023 wines made with vineyard vs. winery N additions at the control and 100mg/L total YAN conditions. At 200 mg/L total YAN the source of N no longer resulted in sensory differences, indicating that lower total YAN wine fermentations may be more influenced by the source of nitrogen. Finally, the residual amino acid profile in wine differed among the field treatments, which could influence wine aging characteristics. Taken together, our findings indicate that while the moderate soil and foliar N applications evaluated in this study may not significantly influence components of yield or primary fruit chemistry, YAN and amino acid profile are affected. Also, sensory differences in wines made from fruit receiving different N treatments in the vineyard and/or winery are detectable by untrained panelists, indicating the potential for N management to influence wine typicity.