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

Soil Bloom petioles Late-summer petioles Nitrogen --- 1.2 – 2.2 % 0.8 – 1.2 % Phosphorus 20 – 50 ppm 0.17 – 0.30 % 0.14 – 0.30 % Potassium 75 – 100 ppm 1.5 – 2.5 % 1.2 – 2.0 % Calcium 500 – 2,000 ppm 1.0 – 3.0 % 1.0 – 2.0 % Magnesium 100 – 250 ppm 0.3 – 0.5 % 0.35 – 0.75 % Boron 0.30 – 2.0 ppm 25 – 50 ppm 25 – 50 ppm Iron 20 ppm 30 – 100 ppm 30 – 100 ppm Manganese 20 ppm 25 – 1,000 ppm 100 – 1,500 ppm Copper 0.5 ppm 5 – 15 ppm 5 – 15 ppm Zinc 2.0 ppm 30 – 60 ppm 30 – 60 ppm Molybdenum 0.5 ppm 0.5 Aluminum < 100 ppm Organic matter 3 – 5 % pH 5.5 V. labrusca 6.0 Hybrids 6.5 V. vinifera

How do nutrients leave the vineyard?

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

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

Cover cropping benefits: • Vigor depression• Erosion control• Less soil compaction • Higher H2O infiltration • Weed suppression • Increased microbial diversity

Background (cover crops)

•Cover cropping issues: • Yield loss• Increased frost risk • Lower ester concentration

and varietal aroma• Competes for nutrients &

water• Lower YAN, fermentation

issues and off aromas

GMV Sauvignon blanc

Pruning weights Pruning weights

<0.3 kg/m: low vigor0.3-0.6 kg/m: balanced

>0.6 kg/m: excessive vigor

aab

bcc

0.20

0.30

0.40

0.50

0.60

0.70

0.80

High soil Low soil Foliar Control

Prun

ing

wei

ghts

(k

g/m

eter

)

• High soil: 60 kg N/ha

• Low soil: 30 kg N/ha

• Foliar: 30 kg N/ha

• Control: no N

GMV Sauvignon blanc

Petiole N% at veraisona

a

ab

ab

ab

ab

b

b

0.40

0.50

0.60

0.70

0.80

2014 2015

Petio

le N

%

High soil Low soil Control Foliar

• High soil: 60 kg N/ha

• Low soil: 30 kg N/ha

• Foliar: 30 kg N/ha

• Control: no N

a

a

aab

ab

b

bc

579

1113151719

2014 2015

Yiel

d/vi

ne (k

g)

High soil Low soil Foliar Control

GMV Sauvignon blanc

Crop yield/vine (kg)• Yield differential

not apparent until year 4 (2014)

• Medium-term investment

GMV Sauvignon blanc

Yeast-assimilible nitrogen (YAN)a a

abbb bb c

40

90

140

190

2014 2015

Foliar N 60 N Soil 30 N Soil Control

• High soil: 60 kg N/ha

• Low soil: 30 kg N/ha

• Foliar: 30 kg N/ha

• Control: no N

AREC Petit Manseng

a a

bb

b

bbc

b

C

b

050

100150200250300

2014 2015

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

Soil sampling depth (in.)

Soil test resultsK (lbs/acre)

2006 0 – 8 2342006 9 – 16 1592011 0 – 12 1582012 0 – 12 1722015 0 – 12 246Crop removal of K, 2008-2015: ~ 214 lbs/acre (~20-30 lbs/acre/year)

K

K

K

KK

KK

K

K

K K KK

Potential for nutrient uplifting

High juice (wine) pH conditions

High pHHigh soil [K+]

(or hi K fertilization)

and H2O

Warm/hot grape regions (low fruit

acidity)

Production of wines

with MLF

Large vines (↑ transpiration and

root system size)

Crop levels and berry size

Shaded canopy

conditions

Rootstock differences

High malate:tartrate

varieties

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)

Deficient Marginal Adequate ExcessiveWGPG

Pet./bloom < 1.00 1.00-1.50 ≥ 2.50Pet./véraison < 0.80 1.20 ≥ 2.00

SJV, CAPet./bloom < 1.00 1.00-1.50 ≥ 1.50Pet./véraison < 0.50 ≥ 0.80

AustraliaPet./bloom < 1.00 1.00-1.50 ≥ 1.50 1.80 – 3.00Pet./véraison < 0.60 1.00 ≥ 1.20

Potassium tissue analysis standards based on leaf petioles (all values are % of tissue dry weight)

Deficient Marginal Adequate ExcessiveWGPG

Pet./bloom < 1.00 1.00-1.50 ≥ 1.50Pet./véraison < 0.80 1.20 ≥ 1.00

SJV, CAPet./bloom < 1.00 1.00-1.50 ≥ 1.50Pet./véraison < 0.50 ≥ 0.80

AustraliaPet./bloom < 1.00 1.00-1.50 ≥ 1.50 1.80 – 3.00Pet./véraison < 0.60 1.00 ≥ 1.20

Current soil K recommendations in WGPG

Target soil K to 150 – 200 lbs K/acre (75-100 ppm)

Current soil K ratings used by Virginia Tech soils lab:

Ext. K K (lb/ac)L- 0 – 15L 16 – 55

L+ 56 – 75M- 76 – 100M 101 – 150

M+ 151 - 175H- 176 - 210

Situations where added K might be needed

- 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

Bottom line

Before planting your vineyard: Add needed fertilizer and amendments before

planting and incorporate to rooting depth (based on soil tests)

After your vineyard is planted: Add only the fertilizers that are needed, and at

only the rates needed (based on plant tests and visual observation)

Add fertilizer at the time of optimal vine uptake Based on fertilizer and application method

Questions?