Nitrogen Fertilizer Calculator for Concord Vineyards (Beta)
This is a Concord Nitrogen calculator based on Lake Erie production for the juice and wine production where Concord is predominantly grown on its own roots and not irrigated. Based on input from soil tests, field observations, and tissue tests, it will calculate N rates for vineyard maintenance and corrective actions. Calculations are based on organic matter decomposition rates for Lake Erie soils, nutrient needs from both vine growth and crop yield, fertilizer uptake efficiency studies, and tissue values collected from the Hi-Res Vineyard Nutrition Project.
Maintenance Nitrogen: This part of the calculator looks at soil N supply based on organic matter decomposition rates for Lake Erie regional soils and N demand from both crop size and vine size from whole-vine excavation studies. Maintenance N rates assume the grower wants to “maintain” the current vineyard status with respect to vine size, yield, and nitrogen status. “I am happy with the vineyard status and just want to keep things rolling.” Large vines with large crops require more maintenance N than small vines with small crops to maintain the status quo.
Corrective Nitrogen: This part of the calculator assumes the grower is not happy with the current vine growth and yield and has confirmed, through tissue testing, that low vine Nitrogen status is the reason, at least partially, for the poor productivity. Corrective N rates are higher with the goal of creating a change in vine Nitrogen status.
Example: In a vineyard with 2% organic matter, a grower has 1-pound vines with 8 tons/acre and 2.5-pound vines with a similar 8 tons/acre. For maintenance, the calculator calls for 15 pounds actual N on the 1-pound vines and 59 pounds actual N on the 2.5-pound vines. But wait…the one-pound vines with a big crop should be stressed out (Ravaz Index = 26). Don’t they need more Nitrogen? The answer is “YES,” but only if nitrogen deficiency is causing the poor vine growth. Upon further investigation, bloom petiole tissue values are 0.8% on the 1-pound vines (indicating N deficiency) and 2.0% on the 2.5-pound vines (indicating good N status). The calculator adds an additional 50 pounds of actual N for the 1-pound vines for a total of 65 pounds of actual N (15 pounds maintenance + 50 pounds corrective). What if all tissue tests came back indicating good N status? Then stick with the maintenance N rates and investigate for other causes of poor vine growth (other nutrient deficiencies, poor water status, phylloxera, etc…)
Enter your own information from soil and tissue tests by adjusting the sliders and see if the calculator gives you a reasonable response for your vineyard management. If not, let me know where you think the calculator is falling short.
