Ten Minutes By Tractor has been using Precision Viticulture since 2007 when we had our first airborne imagery and soil sensing done on our home vineyards in Main Ridge. Airborne imagery, simplistically, measures differences in vine biomass or plant cell density (PCD); soil sensing measures soil conductivity which, in turn, is a proxy for such factors as soil moisture, structure and content.
We have learnt a lot about our vineyards from these images but the key purpose of the images is to highlight variation, in fact variation is the raison d'être for precision viticulture. And it could be variation in quality, in quantity, or in both. And it may be variation spatially or variation over time (for reasons of availability and cost we do not yet concern ourselves with the latter, other than annual variation).
So the question becomes one of our reactions to variation – do we embrace variation or do we attempt to remove it or do we simply try and understand it. As usual with wine the answer, in our case, is not straightforward and is really a combination of all the above.
If we understand variation we can adapt viticultural techniques and management sytems to specific blocks, or sub blocks; if we can identify variation we can seek to minimise it so that for a specific clone on a specific block on a specific vineyard the flavour profile is similar and grapes can be picked at the same time. There is no formula, not everything is picked at 23° Brix and 7.0g/l TA; these natural or basic "terroir units", once identified, must be treated individually.
So the first images of the McCutcheon Vineyard from 2007 are shown below (all airborne imagery images are taken around the time of veraison which for our Main Ridge vineyards averages 5 February).
[A note on the images below. The colours show variation across the vineyard in a relative sense; they do not show absolute values. On the EM38 image below, blue shows the highest conductivity of that vineyard at that time, it then grades through green and yellow and orange as conductivity reduces. Similarly for the plant cell density, blue shows the highest density of that vineyard at that time, it then grades through green and yellow and red as density reduces.]
Soil Sensing EM38 2007
Immediately obvious is the spring under the windmill on the central left of the image (to the west) and the dam and wetlands in the valley at the base of the property on the bottom right (south east) of the image.
Airborne Imagery Plant Cell Density 2007
Shows enormous variation across all blocks of the vineyard. Obvious is the impact of large trees – pine wind breaks along the top left of the image (west) and bottom of the image (south), two large gum trees on the top left of the image (north west) and a large pine tree in the centre of the image.
While intra-block variation was well understood its extent was not fully comprehended until viewed in this format; precision viticulture makes what has been sensed visible. Armed with this information the vineyard team worked closely with the winemakers to isolate the best point to begin separating the harvest to allow the wines to be made individually and assessed on their merits during barrel sampling and blending trials.
The PCD image makes a lot more sense when overlaid on an actual image of the vineyard.
We need to take a step back here and explore further exactly what it is we are doing, what we are looking for.
An article in The World Of Fine Wine (Issue 14, 2006), Ars Enologica: Aubert de Villaine and Domaine de la Romanée-Conti, says...
“It is the obligation of the vignerons, especially those with grand cru properties, to be in a perpetual search for the highest quality possible. In order to do this, the vigneron must adopt a philosophy for the production of wine. The moving force that underlies this philosophy is the notion of terroir...In Burgundy...the concept of a particular place that has an identity that a single type of grape is charged with interpreting is so fundamental to the concept of the wine that it is difficult to overestimate the importance of the concept. It is often difficult for outsiders to understand that, to a Burgundian, he or she does not make Pinot Noir, but rather makes a wine of whatever climat is under discussion; the Pinot Noir grape is just the means of interpreting that climat or terroir.”
So, this is a step in our “perpetual search for the highest quality possible”; it’s a step which accelerates years of observation.
Some of the specific results of our Precision Viticulture program include...
Below are the PCD images for the McCutcheon Vineyard for 2008, 2010, 2011 and 2013.
Airborne Imagery Plant Cell Density 2008
In 2008 we experimented a lot with carefully regulated and monitored irrigation (summer 2008 was dry with no rain in January and both February and March below average). The impact is obvious with far less variation except in the top right block (the Lake Block) which shows second year grafts of 777 Pinot Noir (in orange) and first year grafts of MV6 Pinot Noir (in red).
Airborne Imagery Plant Cell Density 2010
In 2010 we experimented with creating zones in the Chardonnay Long Block (the long bottom area of the image) into a higher or west (left) zone and a lower or east (right) zone and picking them separately. The horizontal (east-west) bands also allude to the different Chardonnay clones on this block - P58 at the top followed by I10V1, I10V5 and I10V1 again.
The upper right area, our Ridge Block MV6, was split between differently trellised vines - VSP in the top half (north) and Scott-Henry in the bottom half (south) - and also picked separately.
The top right Lake Block is still showing signs of the new grafts.
Airborne Imagery Plant Cell Density 2011
Similar comments to 2010 above.
Airborne Imagery Plant Cell Density 2013
In 2012 the Long Block (bottom block on the image) was physically split into higher or west (left) and lower or east (right) blocks and these were picked separately. The I10V1 and I10V5 Chardonnay clones (no longer shown on this image) were replaced with 667 Pinot Noir in the higher or west (left) zone and with clone 95 and 96 Chardonnay in the lower or east (right) zone.
Similarly, the VSP and Scott-Henry split of the Ridge Block (upper left) were also picked separately.
Once again, the PCD image overlaid on an actual image of the vineyard makes more sense. In this image, for example, the new headland and replanting of the Chardonnay block is evident and the removal of trees, particularly along the west (left) boundary, is clear.