Understanding Seasonal Nutritional Requirements

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1 Understanding Seasonal Nutritional Requirements Tips & Tricks Tip 1: Sample Tissue at Critical Times A plant tissue sampling strategy should be implemented each year to monitor vine nutrient status. Follow the steps below to obtain nutrient data for each vineyard block: Step 1: Establish sampling blocks for your vineyard site based on distinguishing characteristics such as grape variety, clone, rootstock, and soil composition. Each block may be 1, 5 or even 10 acres in size if it is relatively uniform and of the same clone and rootstock on similar soil. Step 2: Starting when vines are in their third year of establishment, sample whole leaves or petioles for submission to the lab. Sample at the onset of bloom and again at the onset of veraison to determine current seasonal uptake of nutrients. View instructions for bloom or veraison tissue sampling under Grower Guides on VirtualViticultureAcademy.com. Step 3: Send tissue samples to the laboratory. Place whole leaves or petioles from each block into labeled paper bags, compile all block samples into one box and ship them to the lab with forms to match growth stage at the collection time (note that critical levels will differ at bloom and veraison and the proper form must accompany). Wash tissue samples before sending if the lab does not provide this service. Waypoint Analytical in Memphis, TN provides the added service of washing leaves to reduce pesticide or mineral contamination. The washing is included in the price ($26) per sample. Download forms under Grower Guides on VirtualViticultureAcademy.com. Summary: Tissue sampling will show how well the vine is able to take up nutrients from the soil under the current growing conditions. The results are useful for determining the types and amounts of fertilizers to apply to prevent deficiencies and maintain vine health. The rates of fertilizer to apply will depend upon the level of the deficiency and your specific goals for vine vigor and yield. Standard nutrient ranges for whole leaves and petioles are provided on pages 7 and 8. Copyright Westover Vineyard Advising, LLC 1

2 Tip 2: Know the Nutrition Trends Identification of trends in nutrient deficiency in past seasons is helpful for determining what fertilizers are most likely needed each season in some amount. Follow the steps below to identify commonly deficient nutrients for each vineyard block. Step 1: Compile plant tissue results from previous year (or 2 years if you can). Create a list of nutrients that are either approaching lower end of critical values or are considered deficient for whole leaf or petiole standards (see tables below). Step 2: Note any visual symptoms of nutritional deficiencies observed in the previous season and in the current season. Step 3: Iron Chlorosis Select vigor category to describe growth in previous season: Low Vigor 50% or less canopy fill Moderate Vigor % of canopy fill High Vigor 100% of canopy fill and hedging required Excessive Vigor 100% of canopy fill; multiple hedging passes or shading issues in fruit zone Summary: Grapevine nutrition is not static in vines and must be monitored on an annual basis. Comparing tissue nutrient content in the previous season with that of past seasons is helpful for estimating nutrient decline in vines in time to add fertilizer to prevent deficiencies. Visual cues such as deficiency symptoms on leaves or insufficient canopy offer additional feedback for determining types and rates of fertilizer to apply. Tip 3: Estimate Your Losses Estimation of the nutrient removal from each block with the previous season s crop is helpful for interpreting or predicting decline of individual nutrients over time. Follow the steps below to estimate nutrient loss from each block from the previous season. Step 1: Record yield per acre and yield per vine from the previous growing season. 1. Total Yield Per Block (lbs) / Acres Per Block = Yield Per Acre (lbs) 2. Yield Per Acre (lbs) / 2000 lb Per Ton = Tons Per Acre 3. Yield Per Acre (lbs) / Vine Number Per Acre = Yield Per Vine (lbs) Copyright Westover Vineyard Advising, LLC 2

3 Step 2: Estimate loss of nutrients by block to harvested fruit from previous growing season. Nutrient Average of nutrients removed (Lbs. per Ton)* Tons of fruit harvested per acre Nitrogen (N) 4.0 X = Pounds of nutrient removed per acre Phosphorous (P) 0.6 X = Potassium (K) 5.5 X = Calcium (Ca) 1.2 X = Magnesium (Mg) 0.3 X = *Average of nutrients removed is based on those provided by Markus Keller, WSU. Summary: Each year nutrients leave the vineyard with the grape harvest. Estimation of the potential loss of nutrients with the crop each season will provide you with a big picture overview of the potential shift in available mineral nutrition over time from your soil. Adding back the estimated nutrients removed with the crop may seem logical, however there are several factors to consider before taking such approach. Reasons To Add Nutrients That Were Removed Tissue test reveal a deficiency or near deficiency in critical levels of nutrients. Vine vigor is not adequate for crop level and trellis system. Visual symptoms of deficiency were observed in previous and current growing season and confirmed by tissue tests. Reasons NOT to Add Nutrients That Were Removed: The vines may already be taking in excessive levels of a nutrient (as indicated by tissue test). The vines may be taking in nutrients in an acceptable range, but the addition of more fertilizer may cause competition with other nutrients. For example, potassium (K) levels are within acceptable range and addition of more K may compete with magnesium uptake. Vine vigor is already high, and the grower wants to reduce canopy size. In this case the grower could use very small maintenance rates of fertilizer or choose to use foliar fertilization as an option to add nutrients without causing excess vigor. Copyright Westover Vineyard Advising, LLC 3

4 Tip 4: Know Where Your Nutrients Come From Assessment of past fertilizer applications and understanding how nutrients are introduced to each vineyard block is an important part of developing your season fertilization strategy. Follow the steps below to gain insight on how much of each nutrient was applied in your vineyard as a liquid or solid fertilizer, including nitrogen that may have been added with your irrigation water. Step 1: Record pounds per acre (also referred to as units per acre) of actual nutrients added in the previous year (or 2 years) and note any fertilizer applied in the current calendar year prior to tissue sampling. Use the following example equation to determine the units per acre applied via solid or liquid fertilizers. Also, take note of any foliar applied nutrients using the same equations below. Example for Solid Fertilizer: Ammonium sulfate [(NH4)2SO4] fertilizer contains 21% N or 0.21N/lb of fertilizer. If 100 lbs of ammonium sulfate are applied per acre, the total N application is 21 kbs/acre. 100 lbs (NH4)2SO4 X 0.21 lbs N = 21 lbs N ac 1.0 lb (NH4)2SO4 ac Example for Liquid Fertilizer: Ammonium nitrate liquid fertilizer (AN 20) has a density of Lbs/gal, and 21% nitrogen lbs X 0.21 lbs N X 5 gal applied fertilizer = 11.3 lbs N gal of fertilizer lb of fertilizer ac ac Copyright Westover Vineyard Advising, LLC 4

5 Step 2: Test your irrigation water each year to determine if there are nutrients being introduced your vineyard block each time you water. The most commonly added nutrient with water is nitrogen (nitrate NO3 form). However, it is also important to understand if boron or salts are in ranges that could be toxic to vines. Use the below equations to determine nitrogen inputs from irrigation in both NO3 and NO3-N, the forms commonly reported on lab tests. Example for lab report of ppm NO3: Report from lab shows 45ppm NO3 and a total of 0.89 acre feet (ac-ft) of irrigation water was applied. Step 1: Convert ppm NO3 to lbs N/acre foot of irrigation water applied. 45 ppm NO3 x 0.62 = 27.9 lbs N/ac-ft Step 2: Multiply lbs N/ac-ft by total irrigation water applied per acre lbs N X 0.89 ac-ft irrigation water = 24.8 lbs N ac-ft ac ac Example for lab report of ppm NO3-N: Report from lab shows 45ppm NO3-N and a total of 0.89 acre feet (ac-ft) of irrigation water was applied. Step 1: Convert ppm NO3-N to lbs N/acre foot of irrigation water applied. 45 ppm NO3 x 2.74 = lbs N/ac-ft Step 2: Multiply lbs N/ac-ft by total irrigation water applied per acre lbs N X 0.89 ac-ft irrigation water ac = lbs ac-ft ac ac Copyright Westover Vineyard Advising, LLC 5

6 Step 3: Estimate the nitrogen input from soil organic matter (determined by soil test) and compost additions (if you applied any). It is estimated that for every 1.0% of soil organic matter there will be approximately 20 pounds of nitrogen available over the course of the season. Use the equation below to estimate available nitrogen over the season from compost application. Example for Tons/Acre Compost Applied Wet (as is) compost with 1.7% N content, applied at a rate of 5 tons per acre. Step 1: Convert %N content to lbs N per ton of compost. 1.7 lbs N X 2000 lbs = 34 lbs N 100 lbs ton of compost ton of compost Step 2: Convert lbs N per ton of compost to lbs available N per ton of compost. 34 lbs N X 0.30 lbs available = 10.2 lbs ton of compost 1 lb total N ton of compost Step 3: Multiply lbs of available N per ton by total tons applied per acre lbs available N X 5 tons compost = 51 lbs N ton of compost ac ac Summary: To properly estimate the amount of fertilizer added to each vineyard block, it is important to know how fertilizer is getting into the system. We can precisely measure the amount of fertilizer added from commercial products, however we must also estimate of the amount of nutrients applied with irrigation water, compost additions, and from the nitrogen cycle (organic matter) in the soil. By doing so, we can create a more complete budget of nutrient availability to vines and a better understanding of shifts in nutrient levels in tissue tests. Copyright Westover Vineyard Advising, LLC 6

7 Supporting Charts: Chart 1: Target Values Leaf Critical ranges for whole grape leaf samples used for tissue analysis*. Nutrient** Bloom Veraison Juice and Wine Grapes Juice Grapes Wine Grapes N (Nitrogen %) P (Phosphorus %) K (Potassium %) Ca (Calcium %) Mg (Magnesium %) B (Boron ppm) Zn (Zinc ppm) Fe (Iron ppm)*** > 75 > 75 Cu (Copper ppm) Mn (Manganese ppm) *Excessive concentration of plant nutrients, particularly micronutrients, can be toxic to vines. If tissue nutrient concentrations are significantly higher or lower than these values, contact an Extension specialist to help you review your results. **Molybdenum (Mo) is rarely found to be deficient or excessive in grape, and nickel (Ni) or cobalt (Co) are not established as truly essential in grape. ***Iron (Fe) concentrations can exceed 75 ppm without being problematic for plants; no upper limit has been found for this nutrient in inland Pacific Northwest grapes. Source: Davenport, et al. WSU. Sampling Guide for Nutrient Assessment of Irrigated Vineyards in the Inland Pacific Northwest Copyright Westover Vineyard Advising, LLC 7

8 Chart 2: Target Values Soil & Petioles Nutrient Soil (ppm) Petiole Bloom (%) Late Summer (%) N (Nitrogen) P (Phosphorus) K (Potassium) Ca (Calcium)* Mg (Magnesium) B (Boron) Fe (Iron) Mn (Manganese) Cu (Copper) Zn (Zinc) Aluminum** ph V. Labrusca 5.5 Hybrids 6.0 V. Vinifera 6.5 Organic Matter 3-5% *Calcium level is normally adequate when ph is in the proper range for the grape variety. **Aluminum should not be a problem unless soil ph is less than 5.3 Source: Wolf, T.K., editor Wine Grape Production Guide for Eastern North America. Northeast Regional Agricultural Engineering Service, Coop. Ext. NRAES-145, Ithaca, NY. Copyright Westover Vineyard Advising, LLC 8

9 Chart 3: Compatibility of Soluble Fertilizers for Vineyard Fertigation Source: Fluid Fertilizer Foundation, Fluidfertilizer.com Was this helpful? If you found this guide helpful please visit VirtualViticultureAcademy.com and view other exclusive Grower Guides. Not a member? Whoops... a member must have shared this privileged document with you by mistake. That s ok! No need to feel bad about that. You can become a member of Virtual Viticulture Academy and have full access to all of the grower guides you need to help manage your vineyard. Benefits include live webinars, hands-on field courses, virtual office hours to ask the expert viticulturist, vineyard product discounts and more. Visit VirtualViticultureAcademy.com today to learn more. Copyright Westover Vineyard Advising, LLC 9