There are many potential reasons why a wine grape grower may choose to cultivate grapes organically, or not, depending on their specific environmental conditions, economic potential, ideals or preference. Creating better tasting wine, has historically, not been a primary factor in choosing to grow organic grapes, or adopting growing practices associated with organic farming. However, a new study from UCLA, suggests that maybe it should be.

Analysis of Experts Rating on Organic, or “Eco-Certified” Wines

The researching team from UCLA, led by professor Magali Delmas studied wine ratings and reviews by three leading publications: Wine Advocate, Wine Enthusiast and Wine Spectator, all of which conduct blind tastings to determine their ratings. The team studied 74,148 different wines, from 3,482 different California vineyards. The studied included more than 30 grape varietals and covered vintages between 1998 and 2009. These ratings were put through rigorous statistical analysis, and the researchers found significant differences in flavor ratings for conventionally grown wine grapes, and organic or “eco-certified” grapes, concluding:

Our results indicate that the adoption of wine ecocertification has a significant and positive effect on wine ratings.

The researchers also suggest that these results might even be understated in this report, because some vineyards use eco-certified operations, or organic practices, but are not fully certified.

Of course, this does not mean that they’re aren’t bad organic wines, or exceptionally good conventionally grown wines. There are many other factors in the wine-making process that greatly contribute to flavor and wine quality. However, with such a huge sample size used in their study, this research presents a strong conclusion and a compelling argument for the quality of organic wine. Further examining why these wines taste better in the aggregate can lead to valuable lessons for grape growers in organic and non-organic systems.

Why Does Organic Wine Taste Better?

The most likely reason for why organically grown wine grapes is the soil. There is evidence that wine grapes grown without chemicals, have more abundant and diverse soil microbial activity, and as a result are better able to express the flavors and characteristics of its terroir, the environment the grapes were grown in. In an article from Organic Wine Journal, in 2008, Ron Laughter of Jasper Hill Vineyards said the following, also quoted in the UCLA study:

Flavors are created in the vine. The building blocks are the minerals in the soil. If you keep applying synthetic chemicals, you are upsetting the minerals in the soil. So if you wish to express true terroir, you should be trying to keep the soil healthy. Let the minerals that are already there express themselves in the flavor in the vine.

Healthy soils with thriving microbial activity can be achieved without organic certification, but many management practices associated with organic farming tend to have positive impacts on soil quality and health. A 2011 study published in Applied Soil Ecology, look at the long term impacts of organic viticulture in Southern France. Researchers concluded that, “organic farming led to an increase soil organic matter, potassium content, soil microbial biomass, plant-feeding and fungal feeding nematode densities.” Using grass row covers and organic matter as soil amendments were growing practices that helped improve soil quality.

Soil Quality’s Affect on Wine Flavor

The soil quality and health of the microbial communities present in soil can have a large impact on the microbes present on vines, leaves, and grapes, which in turn, affects how the finished wine will taste. A 2015 study found that the microbiome on a grapevine is largely derived from the microbiome in the soil, specifically microbes found around its root system. The microbial community present on grapevines can play an interesting role in pest and disease resistance, drought stress mitigation, and even frost damage., but it also plays a large role in the flavor of the resulting wine.

Recent research suggests that microbes present on wine grapes can significantly affect wine quality and taste, even on different grapes from within the same vineyard. Fungal communities present on grapes can play a role in the fermenting process, and many microbes affect the aromatic qualities of wine. Microbial populations present in the soil, and on the grapes themselves, will be unique to every terroir. In a general sense, special care given to soil quality, and microbial health, through reduced herbicide and fungicides use, cover crops, and organic soil amendments, should result in better tasting wines, for both organically certified or conventional vineyards.