About NDVI in grapevine producing areas :
Satellite NDVI and NDVI, in general, does not provide by itself data precise enough to be used in a precision viticulture project but it gives enough data to view where precise actions have to be performed. More precise data (various vegetation indices collected by UAV, soil analyses [not resistivity/conductivity],...) has to be collected and ground-truthed in the start of the precision viticulture project. We have collected Landsat8 imagery and calculated several vegetation indices. Landsat8 multispectral imagery is available for free, its ground resolution is not very high (30 m per pixel) but it gives an idea about zones of high (green) vs low (red) NDVI values because these zones are mostly a little larger than this pixel size. Other areas we have analyzed include :
Things move fast in this area, you can now obtain such data at various time frames from several places :
Should you require help in obtaining this data and interpretation, do not hesitate to contact us.
What can be seen here is that high value zones in terms of wine prices and overall quality corresponds to the lowest NDVI places (towards red colour) such as the Pomerol area. Other places have a mix of low / medium / high NDVI values.
Saint Emilion area, France - July 18th, 2016 :
The only conclusion we can draw is that high quality corresponds to low NDVI zones but it does not mean that when you have low NDVI you have necessarily high quality. In mathematics, it is the difference between => and <=>. Hence low NDVI is something that can be interesting to obtain but the reason for which low NDVI is obtained is important, several reasons for low NDVI can exist or co-exist: disease, low N, low P, low whatever, low water... Here we can suspect water constraint, this is why drainage is often tried as a mean to reach high quality. One problem is that current ways of draining vineyards is similar to the way drainage is performed in corn fields (ie longitudinal), but grapevine does not grow the same way as corn does ;-), an enormous difference is that grapevine is a perennial plant with a deep root system designed to bring what is required by the plant (most importantly water). Longitudinal drainage does not take care of "deep" water so it is not adequate for perennial plants, only vertical drainage can be efficient. A well designed vertical drainage system corrects high NDVI and restores high grape quality, a necessary condition to have a high value wine in the end (if oenological steps are performed correctly).
Low NDVI (low vigor) can be detrimental to grape yield and quality as well. There are solutions for these situations too but it strongly depends on the reason why low vigor is present : disease, lack of one important factor (N, P, K, ..., Water). Sometimes, low vigor is due simply to low soil depth which results in "too strong" drainage and consequently low vigor and low yields. This can be detected and taken care of (Iqeus proprietary solution). In other situations, low NDVI results from inefficient drainage (mouillère) which produces root asphyxia and this reduces plant growth, yield and quality; this situation requires vertical drainage too. Solutions exist for many (if not all) cases but it requires to get the good data in order to have the good diagnostic, required to apply the best remedial solution. If your consultant(s) do not provide solutions to your vineyards matters, it is because these consultants are not innovation-minded, they only know how to apply what they have learned, they have no way to imagine new solutions to existing problems. This is what innovation is all about.
This is true innovation in the precision viticulture field, IQEUS is the only consulting company providing innovative solutions, so do not hesitate to ...
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