NUTRIENT REQUIREMENTS FOR GRAPEVINES

Andrew Teubes Viticultural Consultant

Nutrient requirements

• Five (5) critical aspects of importance for grapevine nutrition – Which elements are required by the vine – What the function of each element is – Physiological stage when the element is

mostly required – When to fertilize – How much fertilizer should be applied

Which elements are most important?

• Most important macro elements (required in higher amounts) – Nitrogen (N) – Phosphates (P) – Potassium (K) – Calcium (Ca) – Magnesium (Mg) – Sulfur (S)

• Most important micro elements (required in small amounts) – Iron (Fe) – Boron (B) – Manganese (Mn) – Zink (Zn) – Copper (Cu)

Importance of Nitrogen (N)

• Nitrogen – Growth especially early season – Component in vegetative organs (shoots,

leaves, clusters) – After harvest period for building of reserves

(especially in roots) – 1 ton of grapes remove 1.39 kg nitrogen – High requirement by plant

Importance of Potassium (K)

• Potassium – Most important metal element – High requirement by grapevine especially

clusters – Regulation of water movement in the plant – Very movable – Maturation of canes after harvest – 1 ton of grapes removes 1.98 kg potassium

Importance of Calcium (Ca) • Calcium

– Important in organs (shoots, leaves, roots), especially leaves

– Constituent in cell membranes, permeability of cell membranes

– Important for survival during cold winter (dormant period)

– Strength of berry skins – 1 ton grapes remove 0.17 kg calcium (low

requirement in clusters)

Importance of Magnesium (Mg)

• Magnesium – Essential for photosynthesis, part of chlorofil,

therefore very important in leaves (production of sugar)

– 1 ton of grapes remove 0.09 kg/ton Mg – Low percentage in the grapes

Importance of phosphorus (P)

• Phosphorus – Important for transport of energy through the

plant, especially green parts (leaves, clusters) – Not required in large amounts – 1 ton of grapes remove 0.25 kg P

Importance of micro nutrients

• Iron – Synthesis of chlorofil in the leaves, therefore very

important (photosynthesis) – Deficiencies associated with high pH soil conditions

(soils with free lime)

• Boron, Zink – Important for cell division, especially at fruit set – Development of pollon, very important – Deficiencies cause poor fruit set

Distribution of most important elements in the organs of the vine for the production of 1 ton of grapes (%)

Element Organ Grapes Roots Stem Leaves Shoots Total

N 35.8 14 4.7 31.1 14.4 100 (3.89)

P 34.2 11.4 2.7 39.8 11.9 100 (0.72)

K 64.8 2.5 3.7 15.4 13.6 100 (3.05)

Ca 8.4 1.2 5.7 69.8 14.9 100 (2.01)

Mg 14.9 7.6 4.9 53.9 18.7 100 (0.60)

Value in brackets after total is absolute total in kg

Deficiency symptoms of nutrients

• Every nutrient has symptom of deficiency • Very important to know symptoms of

deficiency, because you need to apply the correct fertilizer to solve the problem

Nitrogen deficiency General yellow coloration of leaves, weak growth

Dark green colour

Vineyard with serious nitrogen deficiency

Phosphorus deficiency General weak growth, leaves curl downwards

Phosphorus deficiency

General red coloration of leaves, veins also red

Yellow color with red spots in late season

Magnesium deficiency

White cultivars Red cultivars

Magnesium deficiency

Symptoms start off as white and then change to red

Potassium deficiency

Burning of leaf edges late season

Yellow coloration of leaf edges early season

Iron deficiency Yellow coloration of leaf with green veins

Boron deficiency

Symptoms on young leaves

Zinc deficiency

Irregular growth of young leaves

Manganese deficiency

Yellowish coloration between veins

Salinity

Soil salinity (sodium)

Foliar application (chlorine)

Availability of nutrients to the vine at different soil pH levels

Be careful for deficiencies -Phosphorus -Magnesium -Iron -Manganese -Boron -Zinc

General soil pH in Afghanistan

7.2-8.3

When is the element required?

• Elements have different functions and is required during different times of the season

• Most common periods for fertilizer applications are: – After bud break – After fruit set – After harvest – Foliar applications through the growing

season

When is the element required? • Macro elements (N, P, K, Ca, Mg) should be

applied to the soil for uptake by roots • Micro elements (B, Zn, Mn, Cu, Fe etc) is

required in small amounts and can be applied through foliar sprays

• Applications of macro elements should be during periods of active root growth – After bud break – After harvest

• Applications must be done with irrigation to ensure infiltration to the root zone

Growth stage Nitrogen (N) %

Phosphorus (P) %

Potassium (K) %

Calcium (Ca) %

Magnesium (Mg)

%

Bud Break to Fruit set 24.2 30.8 41.4 33.3 36.4

Fruit set to Berry Softening

37.5 26.8 30.1 55.5 36.1

Berry Softening to Harvest 5 2 9 7.4 12.8

After harvest 33.3 40.4 19.5 3.8 14.7

Total 100 100 100 100 100

Uptake of different elements during the season

GROWING SEASON

Flow

erin

g

Har

vest

Frui

t set

Ber

ry s

ofte

ning

Bud

bre

ak

62% N 5% N 33% N

Pea

size

Leaf

fall

NUTRIENT UPTAKE BY THE VINE 70-90 days 30-50 days 30-40 days

58% P 71% K 89% Ca 72% Mg

2% P 7% K 9% Ca 13 Mg

40% P 20% K 4% Ca 15% Mg

Fertilizer applications • After bud break

– Only if vineyard has poor growth or no irrigation was available during the after harvest period

– Risk of too much vigour can result in poor fruit set (low yield)

• After fruit set – Very active period of berry growth (cell division) – Important for large berry size – High requirement period

• After harvest – Building of reserves – Extremely important period for growth of next spring

Effect of after harvest nitrogen application on reserve status in roots

Fertilizer applications • Do not apply fertilizer after berry softening or

during harvest period – Requirement low by the vine – Cluster is the most important concentration point,

therefore do not want to encourage active growth – Risk of increased disease if too much nitrogen

applied (rot)

• Only fertilizer applications during this period could be micro nutrients like magnesium and calcium that is required by leaves

High nitrogen fertilizer rates result in compact bunches Sour rot

Botrytis rot

How much to apply?

• Determine what the requirements are by – Soil analysis – Leaf analysis – Calculate what was removed by the crop and

then replacing it (Depletion model) – Visual evaluations

• For nitrogen (N) • For micro element deficiencies

Taking a soil sample for analysis

Transport in clean bag to soil laboratory

Analysis results • Typical soil analysis will give the following

information – Electrical Conductivity (EC)

• Indication of salts in the soil (salinity)

– pH – Contents of Calcium (Ca), Magnesium (Mg),

Potassium (K), Sodium (Na) – most important metal elements

– Content of Phosphorus – Contents of micro elements Copper (Cu), Zinc (Zn),

Manganese (Mn), Boron (B) – Organic matter content

Measure EC (mS/m)

pH P (ppm)

Ca (ppm)

Mg (ppm)

K (ppm)

Na (ppm)

Cu (ppm)

Zn (ppm)

Mn (ppm)

B (ppm)

OM %

Acceptable Levels S=sand L=loam C=clay

<400 5.5-8.0 20 (S) 25 (L) 30 (C)

300 (S)

500 (L)

1000 (C)

40 (S)

70 (L)

100 (C)

80 (S)

100 (L)

120 (C)

<200 (S)

<250 (L)

<300 (C)

5-25 >0.5 >5 1-3 2-3

Norms for interpretation of soil analysis results

Leaf blade analysis norms for grapevines Element Acceptable levels Nitrogen (N) 1.6-2.7 % Phosphorus (P) 0.14-0.55 % Potassium (K) 0.65-1.30 % Calcium (Ca) 1.20-2.20 % Magnesium (Mg) 0.16-0.55 % Sodium (Na) 0-2500 ppm Manganese (Mn) 10-250 ppm Iron (Fe) 60-200 ppm Copper (Cu) 3-20 ppm Zinc (Zn) 15-50 ppm Boron (B) 15-80 ppm

Nitrogen fertilizer applications

• No accurate method of determining the amount of available nitrogen for the vine in the soil

• Evaluate the vigour of the vineyard for determining the N requirement

PLANT PHYSIOLOGICAL NORM Nitrogen

(kg/ha/season)

Bud break After fruit set After harvest

Total N

POOR VIGOUR -Shoot length 50-80 cm -Shoot diameter pencil thickness on average -Shoot ends show poor maturation (browning) -Short internodes (less than 5 cm) -Leaf colour yellow-green ->50% sun spots below trellis -No active growing tips at berry softening

40

40

40

120

IDEAL VIGOUR -Shoot length 110-150 cm -10-12 leaves per cluster -Shoot ends mature completely (browning) -Inter node length 5-9 cm; single tip action required -Leaf colour bright green -20% sun spots below trellis -20-30% active growing tips at berry softening

30

30

30

90

EXCESSIVE VIGOUR -Shoot length 150-200 cm+ -Long, thick, flat shoots common (up to 5 m long) -Regular topping of shoots for sunlight penetration -Large, dark green colour of basal leaves; becomes yellow -Poor fruit set (loose clusters) -High risk of rot -Lateral shoot development very strong

0

0

0

No application

Nitrogen fertilizer applications – Sources

• Inorganic: AN19, AN33, Urea(46), AS(21), DAP(16-18)

• Organic: Cow(1.6%N), Sheep(2.3%N), Chicken(3-5%N), Compost(1%N)

– Application suggestion • Bud break: Depending on vigour • After fruit set: Inorganic source • After bud break: Inorganic source + Organic

before winter

Phosphorus fertilizer application • Required in very small amount by vine • Soil analysis every 3-4 years to determine the available

levels are adequate – 20 ppm for sandy soils – 25 ppm for loamy soils – 30 ppm for clay soils

• Sources • Super phosphate (11.3%), Double supers DSP, TSP (19.6%) • DAP (18% N, 19.8% P) • Phosphoric acid (26%) for applications through irrigation

– pH ranges for uptake 4-6; problems with availability in high pH soils

• Application suggestion – At bud break or after harvest, depending on availability of

irrigation water

Potassium fertilizer application • High requirement by the vine • Use depletion model for annual applications

– 1.98 kg K removed per 1 ton of grapes – 20 ton/ha yield requires 20 x 1.98 = 39.6 kg K/ha/year

(100 kg/ha K-sulfate)

• Sources: – Potassium chloride(50%), K-sulfate(40%)-saline

situations, K-nitrate (13%N, 37%K)

• Application suggestions – 50% after bud break – 50% after harvest

Calcium fertilizer application • Required in low amounts by plant • Soil analysis every 3-4 years to determine if

available levels are adequate – >300 ppm for sandy soils – 500 ppm for loamy soils – 1000 ppm for clay soils

• Afghan soils contain high Ca levels generally, so do not expect deficiencies

• Annual foliar applications can be done to increase levels in leaves if required

• Sources – Gypsum, Ca-nitrate (19% Ca, 15.5% N)

Magnesium fertilizer application • Required in low amounts by the plant • Soil analysis every 3-4 years to determine if

available levels are adequate – 40 ppm for sandy soils – 70 ppm for loamy soils – 100 ppm for clay soils

• Ratio of Ca:Mg = 3:1 ideal • Annual foliar applications can be done to

increase levels in leaves if required • Sources:

– Mg-sulfate (20.2% Mg), Dolimitic lime

Other elements

• Sulfur: Enough applied as fungicide • Boron: As foliar spray pre-flowering on

cultivars with poor fruit set (Na-borate) • Zinc: As foliar spray only when deficiency

symptoms are seen (Zn-sulfate) • Iron: As foliar spray 3-4 times in season

on high pH soils (Fe-EDTA)