Hi Fodder Folks! "Precision Agriculture" is a term you've probably heard.  You may think of farm mechanization, remote sensing, computers, and maybe even drones when you hear it, and you'd be correct in all of those associations.  But does the term "sustainability" come to mind in relation to "precision agriculture"? Precision agriculture seeks to identify in-field variability (and in the foothills, there is ALOT of variability in the soils and topography), and then address that variability in the most efficient way, often using new technology, to ensure a uniform crop and the conservative use of resources resulting in a profitable agricultural enterprise.  Resource conservation, Efficiency, Profitability...sounds like components of sustainable agriculture to me! 

Agriculture today faces a huge challenge in labor shortages. Only recently have foothill growers been looking at investing in mechanical tools to help them get the work done. Last month I held a field day in collaboration with Patrick Tokar, viticulturalist for Rombauer, the same Napa Valley Rombauer that recently acquired the old Renwood winery and tasting room in Amador county.  (I have a friend who only drinks Rombauer chardonnay-a classic buttery chard that's been

called a California icon-but what a pity she's missing out on so many other delicious foothill whites! Vermentino, Sauvignon blanc, Rousanne, Viognier, Greco...oh my goodness, another story on that later surely!).

Rombauer's foothill operation, they've been growing Zinfandel in El Dorado county since about 2007, recently acquired a Pellenc "suck and pluck" style of leafer-a machine

that removes the leaves typically targeting the fruit zone.  Leaf removal allows light and air to penetrate the canopy, critically important for disease control and for flavor and color development in the fruit.  Brad Sporleder and his team from Evolution Equipment Services in Lodi, dealers of Pelenc

Vine canopy AFTER leafing.

equipment, were on hand to explain the leafer's operation and Tiger from Meyer's Vineyard management did the driving.  Patrick noted that it wasn't just the cost of labor, but the proximity of getting labor up to the foothills is a huge challenge in getting work done on time.  The leafer, used on the shady side of the vine rows of course, is used from budbreak to pea sized berries so that it doesn't pull in and damage bunches, and can do about an acre an hour at 2.4 mph. The estimated cost with shipping and set up is about $30,000 (yep, farming

UCANR Ag. Engineering Specialist Ali Pourezza explains the use of remote sensing during my field day at Rombauer vineyards in El Dorado County.

is an expensive business to be in).

In addition to leafing, Rombauer has been using remote sensing and aerial imaging to help them make decisions on the farm.  I invited UCDavis Biological and Agricultural Engineering Specialist Ali Pourezza to explain the fundamentals of remote sensing.  Ali is a recent addition to our ANR Specialist group and is a whiz in creating models of virtural orchards and vineyards and using sensing technology to solve agricultural problems (check out his video of our field day on Ali's twitter!).

Ali explained to the group that light behaves in 4 different ways when it interacts with plants: it is reflected (which is easy to measure), absorbed (which can be calculated based on reflection), scattered or transmitted.  When using remote sensing, a multi-spectral camera is mounted on either a UAV or a plane, and images taken which give information dependent on the spectral resolution (or band width) of the camera. Models are developed to interpret this information, and, (this is super important), calibrated with accurate ground truth data.  The calibration is also critical, and needs to include a "radiometric" calibration-that is, a calibration with the sun's position during the time of imaging (which won't be the same on any given 2 days).

NDVI (normalized digital vegetation index), is the most common and uses near-infrared to red light wavelengths in a scale to tell if green (healthy) vegetation is present or not.  Ali said that NDVI values below 0.1 indicate no vegetation, 0.2-0.5 indicate sparse vegetation, and 0.6-0.9 indicate healthy vegetation.   Other, more advanced indices use other spectral bands, such as NDRE or "red edge".  Ali has been doing some research on using hyper-spectral (thousands of bands!) imaging to detect N₂ (nitrogen) deficiency in vineyards.  Working with Viticulture Specialist Matthew Fidelibus, who ground-truths the sensing data by taking vine petioles for nutritional analysis, Ali is developing a model to predict

vine N₂ status using the NDRE spectrum. 

Rombauer is using Ceres Imaging to do their sensing and Jenna Rodriguez (one of our own UCDavis grads now working for Ceres) also spoke at my field day. After Ali's technical "nuts and bolts" talk, Jenna explained how her company uses remote sensing and modeling to interpret the images provided to clients such as Rombauer.  For example, a blue line on a thermal imaging map was interpreted to be a leaky irrigation pipe.  Low chlorophyll in one area of the vineyard could possibly be soil related.

The tools of precision agriculture and remote sensing can save labor and help pinpoint the need for applications such as fertilizer.  Yet, there's no replacement for "keeping one foot in the furrow", as the late J.C. Walker of UW-Madison, my alma matter, used to say.  Until next time...