By: Becky Garrison
In What Your Food Ate: How to Heal Our Land and Reclaim Our Health (W.W. Norton & Company), authors David R. Montgomery and Anne Biklé expound on their research into regenerative farming practices that can put carbon back into the ground and improve soil health. This research builds on Montgomery’s introduction to carbon farming that he presented at the 2020 Oregon Wine Symposium. (See the June/July 2020 issue of The Grapevine Magazine).
Biklé and Montgomery set out to examine the regenerative practices on farms that grow food crops by assessing 10 farms from California to Connecticut that engaged in these practices. When they analyzed how the topsoil from these farms compared to their neighboring farms, they found three broad principles that are central to supporting soil life. The first was the need to minimize the disturbance of the soil. This can translate into no-till or minimal tillage. The second principle is to avoid having bare soil by keeping the ground covered with living plants. Third, grow a diversity of living plant matter.
Also, they suggested a fourth optional principle: reintegrating animal husbandry. While animals are not necessary for building healthy soils, their presence can serve as an accelerant in speeding up the process.
In Biklé’s estimation, all of these principles are tailorable. He said, “They’re customizable to a given grower’s setting because what’s going to work in in the Pacific Northwest is going to be different than what’s going on in, say, California or upstate New York.” Hence, it’s key to find a mix of species for a particular cover crop that works on a regional basis. For example, a farm in California that’s subject to ongoing heat and drought would benefit from cover crop species that are particularly resistant to heat waves and do not require much water. Also, a cover crop mix can attract beneficial insects specific to a region that are pest predators or provide other benefits.
Biklé adds, “If you think of the soil as having a diet it will be different depending on each vineyard’s unique conditions. In other words, the basic principles and practices of maintaining soil health need to be tailored to the soil. Growers can leverage soil health into vine health and a generally more resilient crop, along with minimizing pests and pathogens.”
How to Assess Soil Health
They recommended assessing the health of one’s soil using the Haney soil test, which was named for USDA scientist Rick Haney. This test includes more than a dozen different soil test values, including standard macro- and micro-nutrients for plant consumption. Compared to other soil tests, the Haney test also estimates nutrients for microbial consumption with a focus on how much nitrogen and carbon are present in the soil.
This analysis enables growers to ascertain not just the nutrients contained within this soil sample but also how the microbes are making these nutrients available to the soil. If these numbers are low, that’s a strong indication of the need to increase the organic levels through practices like cover crops, leaving residue on the ground or planting high exudate producers (a term that refers to carbon-rich materials).
Results of Applying Regenerative Farming Practices
They found that, on average, in less than a decade, the topsoil on the regenerative farms in their study had about twice the soil organic matter and a three times higher soil health score than their neighboring farms. Also, when they compared the minerals, vitamins and phytochemical density in the crops they grew, they found that regenerative farms have roughly a 20 percent higher level of phytochemicals, such as carotenoids, phytosterols and polyphenols. Furthermore, they could not find an instance where the regenerative farm performed worse than the conventional farms in the same region.
In particular, they noted how regenerative farmers constantly observe what’s transpiring in the field.
Putting These Principles Into Practice
At this point, they don’t have data demonstrating specifically how these practices work in vineyards. However, their research into how these practices impact food crops points to some positive practices that Biklé and Montgomery hypothesize can be applied to the vineyard. For example, it’s highly suggestive that cover crops planted between the vines will influence both the microbial communities that the plants interact with and the levels of phytochemicals and potential minerals the vines can pull out of the soil and incorporate into their fruit. The end goal is to create an environment where the vine can succeed by relying on its inherent biology.
Here, Biklé stresses the need to find that sweet spot where there’s just enough stress from physical factors like drought and freeze and biological factors, such as nibbling pests. These stresses cause the plant to churn out phytochemicals. “We know these phytochemicals relate to the flavor and quality of wines, as well as nutritional and health benefits found in wine and other kinds of crops.”
Too often, Biklé and Montgomery find farmers consider no or minimal till an adequate response to carbon farming practices and do not pursue the other principles for maintaining quality soil. As grapevines aren’t plowed over every year, there’s already some minimal disturbance at play. But growers also need to manage the rows between their vines by planting diverse cover crops. While some growers feel cover crops will compete with their vines, As Montgomery reflects, “If you raise cover crops and then knock them down so they become mulch, these cover crops help keep moisture in the soil more than they respire themselves.”
When planting new vines, Biklé recommends doing so with an eye to things like cover crops and animals if a grower is considering those practices. For example, she says to think about the height at which to train the lowest branches to allow enough clearance for cover crops and room for animals like sheep to graze.
On the topic of inputs, Biklé says, “Occasional use of synthetic chemicals like fertilizers or pesticides probably isn’t a big deal in most cases. But their routine use can affect soil health through interfering with the communication and signaling between a vine host and its root microbiome. As a consequence, root microbiota significantly curtail their normal activities, like stimulating vine phytochemical production and delivering water and must-have nutrients to vines.”
Challenges in Adopting Regenerative Farming Practices
In their experience, the biggest difficulty with growers making this switch is their mindset. “If something is working well enough, there’s a reluctance to change,” Biklé opines. Once one can get over this reluctance and adopt an experiential mindset, one can begin to move into the world of carbon farming.
Other concerns include the need to purchase new equipment. In addition, a given practice might be more labor intensive, which can be a challenge, especially if a region is facing a labor shortage. Also, some may not wish to have sheep in their vineyard based on the assumption these animals would disturb their guests or workers.
According to Montgomery, a key concern is the need to develop a regional understanding of what would work for vineyards in a given region. He recommends establishing a consortium of local growers who could collectively experiment with what would make for good cover crops between the vines. These growers could set aside a block where they can tinker in their quest to assess the best practices that work in their particular vineyard. In particular, look for any connection between the polyphenol levels of the wine and what’s present in the soil.
Historically, terroir has been viewed from a winemaking perspective as reflective of the climate, soil and environment. Montgomery and Biklé hope their ongoing research into regenerative farming practices will expand this definition to include an understanding of the soil’s microbial components and how these microbes’ impact both soil health and the quality of the fruit harvested from the vine.
