Fine-tuning vineyard nutrient assessment and fertility recommendations Focus of talk: - Nitrogen – particularly as impacted by vineyard floor management and a need to fully evaluate a range of N indicators…. - Potassium -- interpretation of soil test results, especially under conditions of high K uptake by vines
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Fine-tuning vineyard nutrient assessment and fertility recommendations
Focus of talk:
- Nitrogen – particularly as impacted by vineyard floor management and a need to fully evaluate a range of N indicators….
- Potassium --interpretation of soil test results, especially under conditions of high K uptake by vines
DIY or hire a farm services company
Methods:- Visual (how do the vines
look and perform with respect to yield, canopy/trellis fill, foliage color, and cane pruning weights (0.2 – 0.4 lbs/foot of canopy), YAN?
- Soil tests: Pre-plant and every 2-3 years thereafter.
- Tissue analysis:Routine vs. trouble-shooting.
Test upper and lower soil levels (e.g., 2-12” and 13 – 24”
Target values for soil, bloom petiole, and late-summer petiole samplings
Fruit (per ton)N = 2-6 P = 0.4-0.8K = 3-8Mg = 0.1-0.4Ca = 0.4-2
Pounds/Ton
- Loss of basic cations from soil profile, increased availability of H + and K+
Some nutrients also leave the vineyard through leaching through the soil profile, and by movement (erosion) of soil out of the vineyard.
Sampling for Nutrient Management
Soil analysis tells us what mineral nutrients are available in the soil for vines to access.
Petiole or Leaf analysis tells us what the vine has taken up from the soil.
PLANT TISSUE ANALYSIS
Tissue: leaf petioles from leaves opposite cluster
Timing: Bloom or veraison (pros and cons)
Number: 75-100
Labs: Multiple (e.g., Waypoint Analytical, Penn State, Brookside)
Interpretation: Diagnostic samples related to nutrient sufficiency ranges that have been generated from similar tissues. There is some lab-to-lab variation in sufficiency ranges used.
Beginning of flowering or trace bloom
0 to 30% caps fallen
Bloom or full bloom50-75% caps fallen
Photo: UC Davis
Leaf petiole sampling at bloom
Flower Cap
Petiole sampling at veraison
Veraison 40-60%
• Nucleic acids → DNA → Genes
• Amino acids → Proteins → Enzymes
• Chlorophyll → Light interception → Energy
• Hormones → Communication
• Secondary metabolites → Color, flavor
Chemical component of:
Nitrogen (N): Why it matters
NITROGEN
Presenter
Presentation Notes
Vine to vine variations occur. Shallow spots, hill tops. Aborting shoot tips. (drought contributions)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Vine N demand Soil N supply
Dormancy
Budbreak
Bloom
Veraison
HarvestLeaf fall
Timing N Fertilizer Application• Heavy dependence on stored N reserves from bud
burst through bloom• Uptake mostly during rapid growth (>6-leaf stage)
NITROGEN ISSUES?
– Our tissue analysis standards appear to be overstating the need for N fertilizer in some cases• bloom-time of 1.2 to 2.1% petiole nitrogen• veraison of 0.8 – 1.2% petiole nitrogen
– Use of competitive (for water) cover crops has also increased competition for nitrogen
– Low (< 140 mg/L) YAN levels
Comparison of bloom- and veraison-sampled Cab Sauvignon
Vine size of Cabernet Sauvignon as measured annually by cane pruning weights. Vines with pruning weights of 0.3 – 0.6 kg/m of canopy (box) are considered in balance and capable of ripening full crops.
CC = cover crop used in row middles and under the trellisHERB = vines grown with herbicide strip under the trellis
NITROGEN ISSUES?Our tissue analysis standards appear to be overstating the need for N fertilizer in some cases
• 1.2 – 2.2 %N currently – may be appropriate for American and hybrid varieties
• But higher than what we typically see with vinifera that are maintaining capacity – or are “vigorous”
• Late-summer petiole values (0.8 – 1.2) may also be slightly higher than needed
• Monitoring of canopy color, vine size and crop yields should be used
NITROGEN ISSUES?
– Use of competitive (for water) cover crops has also increased competition for nitrogen
– Low (< 140 mg/L) YAN levels
Complications of cover crops with nitrogen nutrition
Medium soil + Foliar High soil Medium soil Low soil Control
YAN
Wow!!! Foliar Nitrogen really
works!!!
• High soil: 60 kg N/ha
• Medium soil: 45 kg N/ha
• Low soil: 30 kg N/ha
• Medium soil + foliar: 45 kg N/ha soil + 15 kg N/ha foliar
• Control: no N
Summary
o Soil-applied nitrogen was, over time, effective in promoting vine capacity (crop yield and vine size) (medium to long-term strategy)
o Foliar-applied nitrogen (urea) was effective at rapidly increasing must YAN levels (short-term strategy)
Potassium: role in plants
• Phloem loading and translocation of assimilates (sucrose/H+ co-transport)
• Maintenance of water status• Enzyme activation (>60)• Photosynthetic processes
neutralization of electrical chargeATP synthesis
Potassium issues• Situations where K deficiency might occur
- Young vines (e.g., < 3 years old)- Soils inherently low in available K (soluble and
readily exchangeable)- Drought conditions (irrigate)- High soil pH (>7.0) or under conditions of very
high exchangeable Mg or Ca
• Concerns about excess K in vines/fruit- Elevated fruit and wine pH
VINCENT
TEMPRANILLO
CABERNET FRANCPotassium deficiency symptoms
Chardonel, K = 0.71%
Potassium: role in juice pH
citric
malic
tartaric
H+
ATP ADP
K-citrate
K-Malate
K-bi-tartrate
K+
Extracellular sap (pH ↓)
Cytoplasm ( pH ↑ )
Tartaric acid is a weak acid: about 1/900 tartaric acid molecules ionize in water (899 molecules remain as tartrate salt).
Malic acid is even weaker acid. About 1/2500 malic acid molecules ionize in water.
PotassiumData from Zoecklein “pH imbalance in Cabernet Sauvignon”ASEV/ES meeting held in Virginia, March 1987Data from 33 Cab Sauvignon wines from Virginia.
Soil factors influencing K availability and uptake
• Soil texture• Clay mineralogy• Cation exchange capacity (CEC)• Soil pH• Soil moisture, aeration, and temperature• Amount of exchangeable K in the soil and subsoil• Rooting depth
Can soil tests give an accurate indication of K availability?
• Lab extraction (rapid) vs. plant extraction (over longer period of time)
• Topsoil vs. subsoil• Young vines vs. older (deeply rooted) vines
Potassium (and the “potassium paradox”) Virginia Tech’s AREC vineyard, case study- Poplimento-Hagerstown sandy loam- Planted 2006, cropped through 2015- No K has been applied to site in past 20 years
Potassium (Relationship between juice [K+] and juice pH)
High application rates or availability of K can increase berry K+ and can, under some conditions, elevate juice (and wine) pH. Use discretion in adding K to vineyard soils
Can juice pH be lowered by depressing K+ uptake and/or accumulation in berries?
Potassium (Relationship between juice [K+] and juice pH)
Soil (or foliar) K or antagonists
(Mg, Ca, Na)
Plant tissue levels of K+
Berry [K+] and
berry/juice pH
Wine pH
Potassium
From Wolpert et al. 2005. Lower petiole potassium concentration at bloom in rootstocks with Vitis berlandieri genetic backgrounds. Am. J. Enol. Vitic. 56:163-169. Data are means of 3 sequential years.
2011 season K+ (%) 2012 K+
Bloompetioles
VéraisonPetioles
Véraison Blades
Bloompetioles
Herb 2.01 b 3.84 0.90 2.73 CC 2.61 a 3.80 1.01 2.94
NRM 2.12 5.45 a 1.16 a -RBG 2.50 2.20 b 0.75 b -
420A 1.47 b 3.05 0.82 2.13 bRiparia 2.59 a 4.00 0.98 3.16 a101-14 2.86 a 4.41 1.05 3.24 a
Cabernet Sauvignon tissue [K+] as function of ground cover, root manipulation and rootstock. Winchester AREC
TreatmentLeaf petiole K at
véraison (%)Juice [K] at
harvest
NRM (“big”) 5.71 930RBG (“small”) 3.94 701
420-A 3.21 Not measured101-14 5.10 “Riparia 4.93 “
Véraison leaf petiole K concentration and juice pH at harvest with Cabernet Sauvignon planted in rootbags (RBG) or not (NRM) and as a function of three different rootstocks (2015).
Size of root system and grapevine canopy has a bearing on the extent of K uptake and accumulation in fruit.
Average juice pH at harvest, 2012-2014, Cabernet Sauvignon, AHS ARECTreatments: 3 rootstocks 2 floor management schemes (solid cover crop [CC] or interrow CC+ in-
row Herb strip (HERB) 2 root manipulations: none [NRM] or rootbags [RBG]
Potassium tissue analysis standards based on leaf petioles (all values are % of tissue dry weight)