Arable Labs: It has been a wild season for California winegrapes; finally the end of the drought, record-breaking heat spikes at the end of August and early September, and then the horrific fires all across Napa last month.Tablas Creek:
Yes, we had 43 inches of rain this winter; Rocky Butte two ridges over from us had 90 inches! There was water bubbling out of parts of the soil in some places. If you look on a map, our property is about 13 miles from the Pacific Ocean covering about 106 planted acres. Roughly 70 percent of our acres are irrigated, the rest dry-farmed. Our irrigation setup allows us to farm the vine and manage grape cultivation on a vine-by-vine basis. Because of the ample rainfall and complete soil profile, both the clusters and berries were slightly larger than in years past; we had to drop a good amount of fruit and our yields were still 30 percent higher than average.AL: What were the challenges this season?TC:
The heat wave at the end of August really caught us at a hard time within the season. We had an amazing amount of fruit, but we were not at the right Brix to harvest in advance of those spikes. It was strange, over those days some varietals didn’t just shrivel, they completely deflated. Second to the weather anomalies was the powdery mildew — the pressure was higher this season. Powdery mildew does best in a humid environment, and with the rainfall, cooler spring, and the enormous size of the canopies this year, the conditions for disease outbreak were ever-present.AL: I have to ask about the sheep first. How did they help over this season; can you actually see the difference in productivity of the yields?TC:
This year, we had a little over 100 sheep. But you have to think of the sheep as tools (similar to a disk or a wheel) for building the soil and the microclimate for the grapes. Our sheep program has been ongoing for about 5–6 years now. We started out with ten sheep. It seems like it would be easy, but really if you’re not moving them correctly relative to the vegetative growth of the grass, you’ll end of with a mob grazing style — where they over-graze certain sections and under-graze others — and what we really want is more rotational grazing. So, we control their access to different sections and move them on a coordinated schedule. Last year we were able to graze every block, and many blocks twice, because we moved the sheep through fast enough. This cuts down on our number of tractor passes and costs of labor, as well as the amount of fertilizer.AL: I’ve just started learning about holistic rangeland management and how cows can detect changes in the micronutrients of grass, is it similar with sheep?TC:
Think about if you just ate grass all day long, you would know the good stuff! But more importantly, there have been new studies
out recently pointing to how grazing animal saliva helps build immunity within plants. We want to achieve this balance with the plants and with the soil, where there is competition, but that competition makes our vines healthier, more vigorous. With the amount of grass consumed by the sheep, they are packing on about a half pound every day in protein. In total, 10 to 15 percent of the consumption goes to that protein, the other 85 percent becomes manure, or essentially fertilizer, for the vines. We want to develop a really rich, living, diverse soil ecosystem.
If you think about the humid tropics and the amount of biodiversity they have, there is always competition between the plants and soil. You’ll also notice that in the tropics they have less ruminants, whereas in more arid regions we rely on herd animals for microbial transport. This is because ruminants (such as sheep) have four stomachs, making them great incubators for microbial activity. They help microorganisms found in the soil during wet times of year to survive the dry summers. The animals then inoculate the ground the following spring, improving that critical layer of topsoil.
Before World War II, everyone practiced integrated livestock management. The invention of NPK (modern fertilizer) allowed the transition towards monoculture, and what we see now if we think of ‘Food, Inc.’ But finding the balance is important for long-term sustainability, and ruminant animals play a key role in achieving that balance.