Nutrient Management Research Database

The objective of this project was to determine a soil sampling strategy for fertigated wine grapes that reflects soil nutrient availability by tracking the movement of irrigation water and bromide (which simulated nitrogen) in the soils. Bromide was used to stimulate nitrate movement through the wetting zone and vines, as bromide was applied through the vineyard drip system at the first irrigation. Soil sampling zones were established to follow the water and bromide movement. Results from soil moisture analysis indicated that variability in water movement patterns among vineyards may require sampling protocols for each vineyard. Bromide results are a part of a separate study.

• A potassium bromide solution was applied through a drip system to vines with irrigation to simulate the application of nitrogen from drip emitters in two Cabernet Sauvignon vineyards and repeated on two Merlot vineyards.
• Soil samples and plant tissue samples were taken two days after bromide application, two days after the next irrigation, and after the last seasonal irrigation, to determine which soil sampling zone relative to the drip emitter is best for plant uptake, 16 soil samples were taken in a half circle radial pattern around the drip emitter at various depths.

• Results of the soil sampling show that the wetting zone and water movement under the drip emitter varies considerably depending on the vineyard;
  • significant moisture variability is seen in the soil profile 36 hours after irrigation among treatments, even though the soil is significantly moist for all treatments.
• Therefore, to accurately determine the movement of water and available nutrients in the soil for the vines, sampling protocols may need to be individualized to each vineyard.
• Bromide concentrations in the soils are presented in a separate study.