The relationship between soil and wine quality has been recognized for generations but has had limited scientific validation. Vineyard soils in the eastern United States are largely unstudied although proper site selection and good soil management have the potential to improve fruit composition for high-quality wine production. Soils that provide excessive plant-available nutrients and water often produce vigorous vegetative growth and negatively influence fruit chemistry. We investigated three aspects of Eastern vineyard soils, including potassium availability, methods of reducing infiltration, and the influence of topsoil on fruit chemistry. Our first goal was to determine the best soil sampling, processing, and extraction methods for predicting potassium availability in Mid-Atlantic vineyard soils. Excessive potassium can result in high pH fruit, which negatively affects wine quality, but until now the best methods for predicting soil-available potassium had not been investigated. We found that moist-extracted soil sampled from 0-38 cm appear to best be suited predicting vine tissue potassium. Our second goal was to test methods of reducing rain infiltration at critical times during the growing season. One of the soil stabilizers we tested successfully reduced infiltration in field trials. Vineyard trials in 2021 were compromised by dry weather, but further research is ongoing. Our final project involved a three-year investigation where we attempted to isolate the influence of soil properties on grapevines and fruit composition by monitoring vines and fruit in single vineyard blocks. The most consistent result was positive relationships between topsoil and fruit titratable acidity, suggesting that the fruit was ripening earlier in vines growing in thinner topsoil. Topsoil depth better explained differences in fruit titratable acidity than other explanatory variables including crop load and sunlight exposure of fruit. Overall, this research increased our understanding of the soil properties that influence vine growth and fruit chemistry in the Eastern US. The results will help growers improve sampling methods, fruit chemistry, and increase resilience to soil and climate related challenges. / Doctor of Philosophy / The relationship between grapes, wine, and soil has been acknowledged since the Middle Ages when monks recognized that vineyards in different places produced different-tasting wine. However, it is difficult to determine exactly how soil affects grapes and wine. In the eastern United States, growers knew that some soils were not the best for growing high quality grapes for wine, such as those that provide excessive nutrients or water to the vines, but there was little information or scientific research about it. We wanted to help growers by investigating soil properties that affect fruit quality as well as potential soil management strategies that could improve fruit quality. We fine-tuned the process of collecting, processing, and analyzing vineyard samples that growers use to determine the potassium status of their vines. Potassium can affect fruit quality so testing for it before it can affect fruit quality is crucial. We found that sampling soil to a deeper depth than usual and keeping the sample moist instead of drying it were the best practices. We also determined the best way to complete the lab analysis to best predict how much potassium the soil can provide to the vines. For our second project, we found that commercial material intended for stabilizing dirt roads slowed the seeping of rain into soil. Future research will see if vineyards can use the soil stabilizer to reduce soil water during mid-summer rains to improve fruit quality. Our final project involved monitoring vineyards over three years to see how differences in soil properties affected vine growth and fruit chemistry. The main difference in soil was the thickness of topsoil throughout each vineyard. Where there was thin topsoil, the vines were smaller and produced fruit that was less acidic. These results are likely because those fruit were ripening earlier, but we were not able to identify a specific soil property that was affecting the fruit chemistry. Overall, our results will help vineyard growers better manage their soil to hopefully produce better-quality fruit and wine.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/113135 |
| Date | 11 January 2023 |
| Creators | Fiola, Jaclyn Caroline |
| Contributors | Crop and Soil Environmental Sciences, Stewart, Ryan D., Evanylo, Gregory K., Stewart, Amanda C., Wolf, Anthony K. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | Creative Commons Attribution-NonCommercial 4.0 International, http://creativecommons.org/licenses/by-nc/4.0/ |
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