Believe it or not, all of Napa Valley was dry farmed until the 1960s, when overhead irrigation systems were introduced. Just a few years later came the early stages of drip irrigation. Still, the benchmark classics of Napa Valley – BV, Inglenook, Martini and others, were farmed without irrigation for many years before then. How did they manage to do it?

“PivotIrrigationOnCotton”. Licensed under Public Domain via Wikimedia Commons

Dry farming is a practice in viticulture, amongst other agriculture, that relies only on annual rainfall for crop growth. Many old world regions, including most of Europe, prohibit irrigation except for in years of extreme drought. While humidity, climate and environment play a part in how much water a vine needs, parts of regions that do allow irrigation, even here in California, receive comparable annual rainfall.

So why irrigate?

Irrigation supports viticulture in regions in which grape growing would be climatically impossible. When managed correctly, irrigation provides the vine with just enough water to get by. Photosynthesis depends on adequate rainfall, so in a drought, irrigation is important to regulate yields and prevent vines from shutting down.

Today, drip systems allot each vine an incredibly precise amount of water. Growers love drip irrigation because by controlling the amount of ‘precipitation,’ crop estimates are more even from year to year. And so is amount of wine available, and therefore profits. Irrigation makes farming profitable by controlling mother nature. However, controlling mother nature can have consequences worse than an unpredictable crop estimate, just look at the drought here in California. Vines are ill prepared to receive less water than average.

“Drip irrigation system” by Original uploader Agne27

A Chain Reaction

When vines are irrigated, it sets into motion a whole slew of activities that are now necessary. The vine now depends on irrigation for water. Like any plant or tree, roots grow toward moisture. That means they’ll be surface-rooted and unable to reach minerals and nutrients naturally found in the soil Therefore, they’ll need those too from fertilizers and other plant food. The roots are the sensory receptors for seasonal changes in horticulture, but are falsely triggered with surface activity – mainly irrigation, but also pesticides and herbicides, all of which are being taken up into the vines roots and fed to the fruit, but perhaps more importantly, left in the soil.

More to it than Not Irrigating

Dry farming is not simply ‘not irrigating,’ but creating an environment and planning strategically so that the vine can strengthen itself and mature in the proper way as to not need additional water throughout the year. Vines need the correct rootstock whose roots can grow deep to seek out groundwater, as opposed to laterally, where they’ll only be able to reach water sitting on the surface, which is frankly only realistic if one is irrigating. The spacing is important – not too close that they compete for water, but not too far that they soak up too much water. Both of these decisions, as well as soil type play a role in successful dry farming.

Benefits of Dry Farming

Dry farming can (obviously) reduce water usage, but some growers insist that the fruit is more concentrated and flavorful. The smaller, more intense fruit is favorable to some. Quality can and in many cases will decrease. Groundwater, an extremely precious commodity will be conserved, and vines will in turn be more drought tolerant. There’s also many costs saved including energy to pump groundwater as well as building and maintaining drip systems. In addition, dry farming can be a slippery slope into organics and biodynamics, in which case many naturally beneficial systems are applied and vineyards requires less and less human intervention to successfully produce a high quality crop year after year.

Still, in very dry years, it cannot be denied that irrigation is necessary – even in Europe. I believe 2003 was one of those years. Irrigation can save a vintage, sometimes even a vineyard in extreme cases. But if dry farming is the route chosen, in these dry years, irrigation is used only to provide a sense of typical rainfall the region would receive in an average year.

This is getting lengthy, but here are some numbers to consider. Consider some very warm areas of Napa Valley, some which receive (and I’m not talking about lately) 38 inches of rain per year. Dijon in Burgundy receives an average of just under 30 inches of rain per year.

There are many other factors though that play into how much water vines need though, including climate and humidity. However, with water and nutrients delivered to it, it’s relying on these nutrients, not the ones in the soil. The sense of place is diluted and frankly, the wines’ concentration and terroir factor can be too.

There are so many great dry-farmed wines out there. As mentioned previously, almost all wines from Europe will be from dry-farmed vineyards. Some wineries to mention here in California that either practice dry-farming or carry wines that are from dry-farmed vineyards are Frog’s Leap, Tres Sabores, Benziger, and Tablas Creek.