While high yields are the goal, there’s also value in the chemical composition of wine grapes – specifically the Brix level. Higher Brix readings indicate a sweeter grape and also signal the presence of the flavors and compounds needed for winemaking.
Through research, AgroLiquid has shown that achieving the right Brix levels requires a strategic nutrition plan.
Vineyard success
Brix is a measurement of the percentage of sugar solids in the grape juice. In the winery, this translates to potential alcohol content. For the grower, Brix shows the plant’s photosynthetic efficiency. When a vine has the right nutrition, it can more effectively convert sunlight and carbon dioxide into the carbohydrates that fill the fruit.
Our trials on Concord grapevines demonstrate how this works. By comparing conventional fertility programs against an AgroLiquid plan, researchers saw an increase in both yield and sugar density. In this study, the AgroLiquid program achieved a Brix level of 12.0, compared to 11.5 in conventional plots, while simultaneously improving yield to 11.7 tons per acre.
Grape quality
Timing and placement are as important as the nutrient mix itself. Instead of plans that can lead to nutrient lockout or runoff, a balanced program focuses on Nutrient Use Efficiency (NUE).
- Nitrogen management: Too much nitrogen can lead to excessive canopy growth, which shades the fruit and lowers Brix. Using products like High NRG-N allows for lower total nitrogen inputs while maintaining high plant availability.
- Phosphorus: Pro-Germinator provides the phosphorus needed for sugar translocation, so the plant has the energy to move sugars from the leaves to the clusters.
- Potassium: Potassium helps with fruit ripening and water regulation. A high-efficiency source like Sure-K helps make sure the vine can transport carbohydrates during the final stages of the season.
- Micronutrients: Micronutrients like Manganese and the Micro500 blend act as catalysts for enzymes that help the flavor profile and overall health of the vine.
- NUE: In our trials, the AgroLiquid program achieved an NUE of 354.3, which outperformed the conventional program’s 119.1. This means the vines produced better results with fewer total units of nutrients.
Stress
Stress from extreme heat has a major effect on Brix.
“Heat stress starts at 85 degrees, and the vine will start to shut down,” said Abe Isaak, AgroLiquid agronomist. “The leaf stomata closes and will remain closed until the temperature drops enough for the plant to start respiration, and this takes a couple of hours after the temperature drops for this process to restart.”
The vine slows down photosynthesis, and this impacts the Brix because the plant uses the potassium for stress relief rather than building soluble solids in the plant. If the vine is low in potassium this exasperates the effect of the heat stress.
“Front loading the vine with potassium before heat stress starts is vital to combat this issue,” Isaak said. “If the vines have enough potassium, the plant will continue to respirate a couple of hours longer after the heat stress starts during the day, and restart respiration a couple of hours sooner in the late afternoon or evening. This will mean the plant is working four hours more per day.”
In a month’s time, the plant will be respirating for 120 hours more than a plant that is short on potassium. The plant has five 24-hours days per month that it continues to work and increase Brix.
Consistent results
While wine grapes are a primary focus, the same nutrition principles work for all crops. Our research consistently shows that when plants are given the right nutrition at the right time, they are better prepared to deal with environmental risks.
- Cherries: Five-year averages showed yields reaching 14,823 lbs/acre.
- Apples: Strategic nutrition led to both greater yields and the desired firmness needed for long-term storage and marketability.
- Citrus: Growers saw a 0.6 increase in Brix and a 10% boost in overall yield.
Delivering a marketable product
Overall, a more marketable product will meet the standards of both winemakers and consumers. By focusing on a nutrition plan that emphasizes efficiency over volume, growers can improve their harvests year over year. Use AgroLiquid to create a balanced nutrition plan that can give you a high-Brix and high-flavor fruit.
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Abe Isaak is an agronomy manager for AgroLiquid in the western region.