FERTILIZATION AND COVER CROPS Flashcards by R. O.

What is miccorrhizae?

A symbiotic association between a fungus and a plant.The term mycorrhiza refers to the role of the fungus in the plant’s rhizosphere, its root system. Mycorrhizae play important roles in plant nutrition, soil biology, and soil chemistry.

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Name the 4 macro nutrients for the vine

Nitrogen (N)
Potassium (K+)
Magnesium (Mg2+)
Phosphorus (P)

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What is the function of Nitrogen (N) in the vine? (6)

Component of:
Amino acids and proteins
nucleic acid (genetic information basis)
Chlorophyll (convert light energy
Phytohormons (communication within the plant)
Necessary for vine growth and development

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What is the function of Potassium? (K+) (5)

Most active cation in plant metabolism
Respiration and photosynthesis
Carbohydrate metabolism
Breakdown and translocation
Fruit formation

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Why is magnesium (Mg2+) important? (2)

Activation of respiration enzymes
Photosynthesis

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Why is phosphorus (F) important for the vine?

Energy storage and transfer
Cell growth
Root and seed formation/growth
Plant membranes

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With what other nutrients is K competing?

Ca, Mg, Na. Dominance of K will inhibit the uptake of other nutrients

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Which nutrients are uptaken the most around ph 6? (5)

Iron
Manganese
Boron
Copper and zinc

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What is essential for nutrient uptake?

Water

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Which micro nutrients are required for the vine? (5)

Fe - Iron
Mn - Manganese
Zn - Zink
B - Boron
Cu - Copper

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What are the risks of too much N for the vine?

Poor fruitset
Low anthocyanin & phenolics (high risk of sunburn)
Slow ripening
Disease pressure (due to big and dense canopy)

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What are the risks with too high N for the final wine?

Lower tartaric Acid
Higher pH
Higher K
Lower tannin and anthocyanin
Reduced flavour compounds and more herbaceousness

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What are the two forms of N?

Nitrate (NO3-)
Ammonium (NH4+)

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What is the main transporter of N in the xylem?

Glutamine

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Where is an excess of N stored in the vine?

In the leaves, it competes with the carbohydrate reserves

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What are the main uptake moments of N in the cycle of the vine?

During bloom and veraison

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What can cause higher levels of abscisic acid in the vine?

High canopy density - shading
Lack of water
Pests and diseases

Define pH

A measure of concentration of free H+ ions in a solution

What can be caused by a high pH? (5)

High vigor
High N
Leafshading
Keeping old ineffective leaves on the vine

Name 3 types of fertilisers

Chemical
Organic (organic origin, compost/mulch etc)
Biodynamic (manure/preparations etc)

When are nutrient foliar sprays used?

As quick fix
Between flowering and veraison

What is the effect of Increasing N status?

Higher yield
Higher aromatic compound precursors (white)
Higher risk of botrytis
Lower sugar content

How much mg/l YAN is recommended?

150 mg/l

What is ideal soil pH?

6-7

What are the two main things to consider when deciding on fertilisation?

Soil analysis Plant behaviour (vigor)

What can you do if the YAN is too low? What is too low?

<120 mg/l Compost addition in order to increase the OM

When is YAN too high? And what can you do about it?

>200 mg/l Cover crops with high competition

With what nutrients is the CEC relevant?

K and Mg

Why causes too high N a delayed maturation and higher AC levels in the berries?

More leaf area --> more pruning weight --> vine is focussed on growing instead of grape ripening

What is the difference between high N levels for white or red wines?

White: higher yield and vigor, lower sugar, higher aromatics Red: lower color, anthocyanin and tannin

What does an increase of N with the levels of glutathione?

It increases

What does glutathione?

It is a sort of protector of wine, good for ageing. It avoids oxidation by 'hunting' for quinones

What does glutathione?

It is a sort of protector of wine, good for ageing. It avoids oxidation.

What are positive consequences of cover crops? (5)

Decrease erosion Decrease runoff Decrease leaching Increase water infiltration Increase soil aggregate stability

What do cover crops do?

Fixate N Release N after mulching/mowing and mineralisation Provide food of micro organisms Out grow undesirable weeds Can improve access to the vineyard - Could host predatory insects

What releases accumulated nutrients quicker, mulching or mowing?

Mulching (2-9 weeks)

What are the negative impacts of cover crops?

Competition for water Competition for nutrients Reduction of vineyard temperature --> attract frost Extra cultivation needed --> risk compacting the soil

What is the aim for % Soil Organic Matter?

2-4%

Why are earthworms important in the soil?

Because they will create poes that arre big enough for water to infiltrate

The higher the C/N ratio, the...

Longer it will takes for the material to decompose

Describe how temperature and soil moisture influence mineralisation of organic material

Temp: in winter the temperature is too low for much mineralisation Moisture: dry soils slow mineralisation down

How come that cover crops increase frost risk?

Reduced solar interception, lower topsoil temperatures Raising the level of cold air to nearer the vine canopy depleting moisture content from topsoil.