Mosel Winegrowers’ Focus On Soil Health Improves Wine Quality

Soil type has long played a key role in viticulture. However, limited scientific understanding beyond type paved the way for destructive farming to the vast microbial world living within the soil.

Nik Weis, owner and winemaker of Weingut Nik Weis – St. Urbans-Hof, believes the introduction of industrial agrochemicals and soil cultivation into Mosel viticulture destroyed the microbial soil balance of the storied wine region.

“I used to think we needed to return to the way viticulture was done in the Mosel 150 years ago. I was wrong. Back in those days, people were cultivating the soil—taking the living surface and putting it deep in the ground, they were destroying the biome,” he shares.

Scientific advances elucidate the monumental role soil microbes—known as biome—play in the health of a vineyard, and in combating climate change perturbations.

Impacts of climate change are wreaking havoc on Mosel vintages. After three consecutive years of excessive heat coupled with late season frost and periodic hail storms, 2021 brought an abundance of rainfall and decreased temperatures, resulting in yield losses from widespread powdery mildew, for some as high as eighty percent.

The weather roller coaster has some German winegrowers reconsidering longstanding protocols, such as irrigation, vineyard aspect, grape varieties, and vine density. By incorporating viticultural practices that bolster a healthy soil biome—organic, biodynamic, and regenerative agriculture—thoughtful Mosel winegrowers are strengthening vine resilience while improving overall wine quality.

Despite 2021’s deluge of rain, water is a limiting factor in Mosel viticulture. Healthy soil is rich in organic nutrients. Elevated temperatures, flooding, and prolonged drought compromise the microbiome, forcing vines to choose: Produce less fruit, lower quality fruit, or die.

Soil microbials and vines live in a delicately balanced quid pro quo relationship. Through photosynthesis, the vine pulls CO₂ from the atmosphere, converting it in part into exudates to feed the soil microbes. In turn, the microorganisms create a force-field around the stationary vine’s roots, while also providing nutrients from beyond the vine’s reach. This symbiotic relationship buttresses the vine’s ability to withstand stress.

Historically, monocropping has been the choice of winegrowers. Native flora growing within a vineyard was seen as competition for water, risking the life of the vine. Research now indicates biodiverse plant life strengthens the biome as well as the vines. Terminating chemical herbicide and pesticide use is key in promoting biodiversity.

Upon purchasing Weingut Immich-Batterieberg in 2009, Gernot Kollman’s first act was to abruptly end forty years of herbicide use in the vineyards and initiate organic practices. In just three years the vineyards were green, and by the fifth-year balance was restored. “For me it was the only decision,” he shares.

After enduring an initial shock from the sudden change, Kollman explains in just three years the entire vineyard was green, and by the fifth-year balance was restored. Today, vineyard grounds are filled with wild herbs and grasses, living in harmony amongst the vines. “We see how fast nature is at restoring itself,” he shares.

The natural cycle of ground cover growing amongst the vines bolsters the topsoil’s rich organic top layer, known as humus. Acting as a sponge, humus collects rain, then effectively distributes it to the vine during prolonged drought. Additionally, during heavy rain events, ground cover aids in erosion prevention. This is key in steep Mosel vineyards such as Batterieberg Vineyard, which slopes 45°.

“Organic practices not only protect the microbiome, it makes it happy,” shares Kollman. “And, the inner concentration of the wine has improved. Healthy grapes, low quantities, good concentration, and stabilized vineyards.” Textbook rehabilitation.

Thorsten Melsheimer, fifth generation Riesling winegrower, began organic practices at Weingut Melsheimer in 1995, with the main purpose of omitting synthetic chemicals in his vineyards. After growing in awareness of nature’s rhythms he converted to biodynamic viticulture, becoming Demeter certified in 2013. “This means I try to understand the complex coherences of our planet and let them influence my daily work,” he shares.

Witnessing improved health in his Mullay-Hofberg Vineyard post conversion, Melsheimer believes a healthy vineyard resembles nature. He avoids disturbing the soil, opting for animal grazing in the winter for cover crop control. Rather than seeing the vines as the center of the vineyard, he focuses on biodiversity of the entire ecosystem.

“You can find enormous biodiversity in this little part of the valley that we are responsible for,” he shares.

By focusing on soil health, Melsheimer’s Riesling has improved over the past twenty-five years. His vines produce riper grapes with thicker skins, offering protection from sunburn and hail, while amplifying tannins.

He believes long ago the world established a definition of fine Mosel Riesling by valuing the final taste regardless of process. By elevating process over results, Melsheimer creates high-quality wine in balance with nature.

Following nature’s lead in cultivating a healthy biome is simple. Bare ground is rarely seen in nature. Biodiversity promotes healthy, living soil, strengthening flora and plants.

Scientific advancements understand soil biome akin to the layers of a montane ecosystem. The stratification is crucial in upholding the integrity of the microbial communities. Tilling the soil destroys its delicate horizons, like pulverizing a tomato in a blender.

“When thinking of the biome, the key is to consider what nature has in mind. You have to give the vine the best possible conditions as close as possible as it is to nature. Minus those things that threaten the vine,” shares Nik Weis, owner and winemaker of Weingut Nik Weis – St. Urbans-Hof. He collaborates with nature through biodynamic practices, bolstering vineyard biodiversity.

Even in the steep slopes of the Mosel, tilling is utilized by some winegrowers. “Some plow their vineyards to death,” shares Kollman. “From the soil situation, the microorganism situation in the vineyard, it’s not a big difference than using herbicide.”

Constant disruption of the biome’s stratified horizons prevents a burgeoning ecosystem, limiting the vine’s potential. “The vine draws its life energy from the soil microbiome. It is very important the microbiome is intact so that the vine is intact,” shares Weis.

Until recently, Mosel winegrowing, like the rest of the world, focused on vine cultivation and wine production, without consideration for environmental impact. Climate change challenges this limited thinking. “Before this century people didn’t really think about the source of wine, the soil, and how important it is. Maybe we needed all the challenges of global warming to start thinking about these things,” shares Weis.

Scientific understanding of the how farming impacts soil biome is advancing rapidly. Modern research promotes working in harmony with nature. “We must find a way of farming that makes the world better. We must treat our surroundings, our microbiome, well,” shares Melsheimer. “And we must find a new definition of a good wine, away from the wine-first thinking.”