Let it Rain, Rain, Rain
"With life being short, a guy like me does not have time to achieve certainty all the time. Sometimes I pull the trigger when I reach a state of probability. Then I stand back and watch."
After 25 years I'm still dealing with a game of chance, and it's not because I choose to be a gambler. It's because when you start principles from scratch, you don't attain a state of certainty overnight. It’s especially true in farming where developments happen slowly. Your vineyard can only provide you with an opportunity to harvest your theories and run your trails once a year. With life being short, a guy like me does not have time to achieve certainty all the time. Sometimes I pull the trigger when I reach a state of probability. Then I stand back and watch.
When I first started farming in the early 80s, drip irrigation, the process of delivering water to the vines through drip lines, was still sort of new. There were plenty of vineyards out there that were hold outs, having only the traditional overhead sprinklers. As time went on, drip became the textbook solution for nearly every vineyard’s irrigation needs. While we did not remove our overhead system, we too followed the gospel, and installed a drip system.
Of the two systems, it's drip irrigation that puts the water right on the target. There is much less evaporation, and you can water more acres at any one time. With the water being delivered right to the zone of the vine's roots, you tend to have more control and it’s easier to regulate the vines’ growth. On the flip side, less water per irrigation means that the vines tend to run out of water more easily. Thus, you end up watering the vines more frequently, or "nursing the vines” as we call it. With overhead irrigation you end up putting on more water with less precision, but typically end up watering less often. While I do like the efficiency of drip irrigation, over the years I started to feel like we were missing something when we used only the drip.
One of the pluses with overhead, is that it can provide a way to deliver frost protection. In the spring, after the tender shoots start to push out of the buds, if you get a real cold night, those shoots, and that year’s crop that is located on those shoots, can be annihilated by frost. If you have overhead sprinklers, you can turn them on and as the water starts to freeze on the vines, it creates an insulting layer that protects the vines fragile tissues. Another reason for overhead is that you can water the plants that you might be cultivating in the middle of the rows between the vines. More growers are starting to do this because a strong “cover crop” can actually bring nutrients to vines. It can also assist in the biological balance of various insect populations in the vineyard, as well as simply keeping the dust down. Drip lines are not capable of serving up water to those areas. So, if you want to water the strips of cover crop in your vineyard, you have to have overhead.
While I have been aware of the practical aspects of overhead irrigation since day one, it was a few years ago when I started to feel a more emotional attachment. That’s because it was a few years ago that I began my fascination with the phenomena of Terroir. I became very impressed with the idea that a wine’s signature is its soil, and I started having trouble with the fact that my vines were being confined to growing in the hydration sphere right under my drippers. The more I thought about it, I realized the vines were being forced to grow, and only grow, in that little pocket of soil. ‘But look at all this ground,’ I would think to myself as I tried to wrap my brain around the issue. The terroir is not confined to the dirt under the drippers. The terroir is all the dirt. That's when I had this epiphany. What if I was to put on a sizable irrigation through the sprinklers right at the moment that I considered to be my window of opportunity?
That moment is the middle of veraison. Veraison is the point in the vine’s development, usually in August, when the berries turn soft. It usually takes about 3 weeks. With red varieties, it's also the point at which the berries develop their color. Prior to verasion, from March through July, it is challenging to put on overhead irrigation because it can encourage outbreaks of mildew. After verasion you don't want too much water too close to harvest for fear of prompting bunch-rot problems, and you want to avoid diluting the intensity of the grapes and thus the wines. Prior to my epiphany I thought the only way to get the vines through their growing season was to nurse them with the drip.
Well, I have grown tired of nursing the vines. I have also grown tired of a dead cover crop and the dust that ensues. I'm to the point of needing a psychiatrist because my vines are only growing in the wet spots under the drippers. I am going to water at veraison this year, it's going to be through the overhead, and it's not going to be some wimpy amount. It's not going to be me second guessing all this because I am not aggressive enough, and I end up nursing the vines anyway. No, it's going to be enough water so that I don't have to water again before harvest. This August it's going to rain on the entire Ocean’s Ghost section of my vineyard, and as far as those vines can tell, it's going to rain 4 inches! It's got to all happen in one night because, my theory is, if I stretch it out over 2,3 or 4 days, then I really am asking for problems. I'd be encouraging some kind mold, and I wouldn’t be able to get a tractor into the field to address such a complication because the ground will be too soggy for too long. I have to get 4 inches on and I have to get it on fast.
It was called bore-hole irrigation because the first time I tried it, I only got about an inch down. Why? Because the nozzles in the sprinklers were not made for farmers like me. They were conventional. They put out a normal amount of water. I told my vineyard manager, that I needed more flow. So, he took the nozzles to shop and he bored out the holes. It's funny how I look at stuff like sprinkler nozzles with bigger than normal holes and I think to myself, "They’re beautiful."
In the days and the weeks after we first tried those nozzles on a very small section of the vineyard last year, we saw a number of interesting things. For starters, the vines loved the big drink. Their shoot tips got perky and they turned a greener shade of green, as if to say, "Thank you!" They didn’t need any more water through the harvest, and I thought they were in better balance than the vines in the rest of the vineyard where we continued with a drip–only program. Dust? Through harvest, the dust was gone, and the residual moisture in the soil helped to expedite the planting of a new cover crop immediately after harvest without having to irrigate much further.
Why is that important? It’s two-fold. For starters, once we start picking grapes, we hardly have time for anything else. If anything outside of the actual harvest is going to be too cumbersome, it has to be postponed. Now I can quickly drill in my cover crop right after each field is picked because the soil already has the appropriate amount of moisture for those seeds to germinate. This is crucial because if your cover crop is a legume, you want to mow it at full flower. That's when you get the full bang for the buck in so far as the plants fixing nitrogen in their roots and thus becoming a nutrient source for the vines, like manure. If you mow too soon, you don’t capture the full nutritional impact. But you need to be able to mow it down on or around the beginning of March, because if your cover is still in, it tends to push cold air higher up into the vine’s canopies on those potentially frosty nights after spring bud break. So, you not only need to get on with planting your cover right after you harvest, you need that cover to grow like gang busters so that it will be in full flower come the end of February. On March 1st we want to be able to kill the flowers as we call it. That's our terminology for mowing a healthy, full flowering stand of leguminous cover; the considerable thatch from which helps to keep the dust down during the earlier part of the summer.
Now, I am allergic to legumes. Peanuts are my death. I have a hard time appreciating a freshly mowed field of something like vetch. But what I am really starting to appreciate is the apparent downstream affects of bore-hole irrigation. The vines seem to love it, and I think it makes better wine. Being an ardent believer of cause and effect, it is interesting to me how well it flows. When you get the timing down on all these things, they just seem to naturally integrate.
I would not say that I am a radical for all this just yet because it's still a bit theoretical. I need to look at it fully implemented and coordinated with our drip system for a few years to make sure I’m not creating any problems that I don’t yet know about. But you have to start somewhere, and this year Ocean’s Ghost is getting four inches of rain.
I think at this point, I hope at this point, that the benefits will out weigh any costs. In the mean time, I have come up with a new name for the technique, “Saturasion Irrigation”, in other words, a saturation-irrigation at verasion.