 |
|
|
|
 |
|
||
 |
 |
|
|
 |
 |
|
|
 |
|
|
|
|
|
|
|
|
|
|
 |
 |
|
||||||||
 |
|
|||||||||
 |
 |
 |
|
|||||||
 |
|
|||||||||
 |
 |
 |
 |
 |
 |
 |
 |
|
||
 |
 |
 |
 |
|
||||||
The ability to optimize winegrape production necessitates an understanding of the factors that influence their spatial and temporal variability. The majority of precision viticulture has focused on investigating the link between winegrape parameters and above-ground factors, such as the training, cultivation, and harvest timing of the grapes. Soil properties, which control water drainage, are also critically important to winegrape quality, although not as much emphasis has been given to investigating the role of soil properties on winegrapes as has been given to above-ground factors. This is partly due to that fact that heretofore, most soil characterization has been performed using invasive methods (such as by digging backhoe pits or collecting point measurements). These techniques are invasive and laborious, and yet still provide information at a single point in time/space only, which is often insufficient to capture the field-scale variability in soil properties that are observed in vineyards. Because vineyards are not typically planted nor managed with a good understanding of natural soil property variations, spatial variation in winegrape quality is common, even when all farming practices are constant throughout vineyard blocks.
Our projects focus on integrating non-invasive and spatially exhaustive geophysical data with sparse direct soil measurements to estimate soil parameter spatial distributions over space and time, and to investigate the influence that these variations have on winegrapes. For example, we have investigated the applicability of ground penetrating radar (GPR) methods to provide very high resolution estimates of near surface water content within the Robert Mondavi Vineyard in Napa County and the Dehlinger Vineyard within Sonoma County. Comparison of our geophysical estimates with conventional measurements of water content, soil texture and plant vigor measurements has illustrated that the estimates are accurate and reliable, and that water content, soil texture and plant vigor are correlated.
More recently, we have been working with Phil Freese of WineGrow to investigate the impact of utilizing high resolution soil property information, obtained from geophysical methods, to guide the optimal development of vineyards (such as the row and vine spacing and irrigation parameters), so that winegrapes within vineyard blocks develop uniformly and with high quality characteristics.