Water, as with all things in farming, is about balance. I give my vines just enough water to get them through the season healthy and with a good crop. Some years, though, I’m lucky to get even enough water to do that.
The Carneros is a stretch of gently rolling hills embracing the northern tip of the San Francisco Bay. The soils are young - give or take a million years - shallow and lean. Topsoil is a wistful euphemism balanced atop a hard pan. Below this, if you can find it, sits trapped brackish, barely potable water. The boron and heavy metal content is generally so high as to render the water useless for irrigation. With wells out of the question, we hardy Carneros farmers rely on reservoirs and streams - filling our ponds with rain water. We spend the beginning of every rainy season praying for enough - and not relaxing until our ponds are full. It means we are closely tied to the seasons in a very immediate way - I do not have the cushion of a well’s savings account. We are cash only, spending our rain in the same season we accumulate it.
I was recently asked if wine grapes need water to grow. The answer is yes - and no. There are many variables to this - how old is the vineyard? You definitely need to irrigate the young vines until they establish. What type of soil do you have? The deep, rich loam of the Napa Valley floor has seemingly endless topsoil and a high water table. Makes it easy to dry farm, if that is your proclivity - and if you are not adverse to heavy tillage. And, regardless, there has to be some moisture in the soil to begin with.
My vines generally have less depth than the width of your laptop screen for root space. Below that, the vine roots hit an impenetrable wall, as hard as a concrete foundation. Nothing gets through. All the moisture my vines use in a season is contained within that minuscule scrap of “topsoil” - otherwise known as unforgiving, gray clay that cracks apart as it dries, often tearing the roots with it. Increasing organic matter, improving tilth with livestock, cover crops, minimal tillage and soil amendments is of paramount importance when farming in the Carneros - it helps to retain moisture, keeping the soil from cracking. (I really am a dirt farmer.)
We could try to dry farm, but it would render the vineyard economically unviable; we’d lose up to two-thirds of our current crop with yield reductions due to water loss. Never mind the vines not living as long with the high amount of stress. Also, the heavy tillage would reduce the clay soil to dust. Why so much tillage with dry farming? Cultivating reduces the amount of competition for moisture between the cover crop, weeds, and the vines.
Climate change is not making it any easier - more extremes in weather means more drought. Enter 2013, driest calendar year on record. I have a reservoir so dry you can walk across it, there is not even the memory of water and the fish skeletons are long gone. Planning for another dry year is what is keeping me up at night. In some areas, I might cultivate more - spending the soil’s bank account of fertility and moisture to make it through the season. Other spots, but not all, I have access to different water sources - such as high quality recycled water.
I’m trying not to panic. I think we can limp through this year. But next? I see diminishing and diminishing returns on our grapes. So, as you turn on your tap, with the water always available, think of us farmers and pray for a “March Miracle” of rain to fill up our reservoirs and to start recharging our wells. Hope for enough rain for us, for the fish, for all. Your drink - and your food - depend on it.
Originally posted on Nopalize