Chapter 34

Precision Viticulture

Variable-Rate Technology

Numerous areas within the vineyard differ from one another in terms of soil type, topography, microclimate, and other factors that impact crop yields. Variable-rate application (VRA) has been widely heralded as a means of applying crop inputs (e.g., pesticides, fertilizers) in a non-uniform manner, based on varying needs throughout a vineyard. Its advantages include higher average yields, lower input costs, and environmental benefits from applying fewer inputs. There are two ways in which automated variable-rate technology (VRT) can be utilized for site-specific crop management (SSCM) systems. These are map-based and sensor-based systems. There are advantages and drawbacks to both application systems. Generally, map-based variable-rate applicators require more components than sensor-based applicators; however, this is offset by the fact that these components can be used for multiple inputs.

Variable-Rate Application Technologies

There are various variable-rate application (VRA) technologies available that can be used with or without a global positioning system (GPS) system. The two basic technologies for VRA are: map-based and sensor-based.

Map-Based Variable-Rate Application

The map-based method comprises a controller, sensors, and actuators (devices that respond to signals from controllers) to adjust inputs based on a pre-made electronic map of the input, utilizing a differentially corrected positioning system to determine the applicator’s position in the vineyard. Application maps may be constructed from yield, topography, soil, plant, or weed data. Map-based systems enable growers to make informed decisions based on knowledge of the vineyard before they enter it. This also gives the grower precise control over how much of an input is applied to a specific region in a vineyard. Map-based variable rate controllers are attached to standard vineyard equipment. They can be used to control the rate of dry chemicals (granular fertilizer, granular pesticides, gypsum, lime), herbicides, and pesticides.

Sensor-Based Variable-Rate Application

The sensor-based method enables the capability to vary the application rate of inputs without prior mapping or data collection. Real-time sensors measure the desired properties—typically soil properties or crop characteristics—while the system is in motion. Measurements made by such a system are then processed and used immediately to control a variable-rate applicator. The sensor method doesn’t necessarily require the use of a positioning system, nor does it require extensive data analysis before making variable-rate applications.

Applications of Variable Rate Technologies in Precision Viticulture

Variable-rate technology (VRT) in vineyards is a cornerstone of precision viticulture, enabling growers to apply water, fertilizers, pesticides, and other inputs site-specifically rather than uniformly across the entire vineyard. This optimizes resource utilization, enhances grape quality, and promotes sustainability.

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