Soil pH improves Concord mineral nutrition
For Concord production, the target soil pH window is 5.5-6.5. When raising soil pH in an existing vineyard, apply no more than 2-3 tons/acre/year of lime until you hit the target.
Soils in the Lake Erie AVA tend to be strongly acidic (pH 5.0-5.5) to very strongly acidic (4.5-5.0) and this leads to poor vine growth and fruit production. Below a soil pH of 5.2, high aluminum solubility limits phosphorus availability and grapevine root growth and soil cation exchange capacity (i.e. nutrient holding capacity) decreases because of pH dependent changes in the organic matter soil fraction. Poor root growth leads to an overall reduction in vine size and poor nutrient availability leads to a complex of magnesium, potassium, and phosphorus deficiencies, often referred to as “acid soil sickness.”
Adding lime to the vineyard floor increases soil pH, soil cation exchange capacity, and the balance of cations (calcium, magnesium, and potassium). Raising the soil pH above 5.5 eliminates aluminum toxicity and phosphorus deficiency, improves root growth and mineral nutrient uptake, and increases vine size and fruit yield. The sweet spot for soil pH in Concord vineyards is between 5.5 and 6.5.
If the pH goes too high (above 6.5) or if too much lime is added in one application in an established (no-till) vineyard, potassium deficiency can be induced. As the soil pH increases, calcium and magnesium soil availability increase at a much greater rate than potassium. There is also a competition between magnesium and potassium in root uptake. In addition, the increase in vine size inevitably leads to an increase in crop size and Concord fruit has a high potassium demand. This dynamic interaction between nutrient availability, uptake, and demand can lead to potassium deficiency, which will dramatically reduce fruit maturation and vine size. To mitigate the risk of potassium deficiency, potash (potassium chloride) fertilizer is recommended for high producing Concord vineyards.
