3.3 Nutrients

Question 1

Where does the vine acquire its nutrients?

Answer 1

Soil

Question 2

What factors do nutrients influence?

Answer 2

• Healthy vine growth

- Yield and composition of grapes

Question 3

Do vines require high or low levels of nutrients?

Answer 3

Low

Question 4

What are the 5 most important nutrients for vines?

Answer 4

1. Nitrogen
2. Potassium
3. Phosphorus
4. Calcium
5. Magnesium

Question 5

What is Nitrogen essential for?

Answer 5

• Vine growth
• Major impact on vine vigour and on grape quality.
• Component of chlorophyll (required for photosynthesis)
• Sufficient levels of nitrogen in the must “feeds” the fermenting yeast avoiding stressed yeast (which produce sulfur compounds).
  Nitrogen is sometimes added to correct a blocked fermentation.

Question 6

What happens if there is too much Nitrogen in the soil?

Answer 6

• Excessive vegetative growth
• Sugar diverted to the growing shoots and leaves rather than the grapes, hindering ripening
• Poor ventilation (leading to fungal disease) unless adequately managed.

Question 7

What happens if there is too little Nitrogen in the soil?

Answer 7

• Reduced vigour
• Yellowing of vine leaves
• Problematic for fermentation

Note: restricted levels of nitrogen produce hiQ grapes

Note 2: sufficient nitrogen in must “feeds” the fermenting yeast avoiding stressed yeast which produce sulfur compounds. Nitrogen my also be added to the must to correct a stuck fermentation.

Question 8

What is Potassium essential for?

Answer 8

Is used for

• Vine growth
• Regulates the flow of water in the vine

Too high?

• impacts the uptake of magnesium (which is needed for photosynthesis) therefore - reduces yield and ability to ripen
• high potassium in soil is linked to high PH in grape must

Too low - results in

• low sugar accumulation
• reduced yields
• poor vine growth

Question 9

What is Phosphorus essential for?

Answer 9

Important for

• Photosynthesis
• usually sufficient in the soil

Too little results in:

• Poorly developed root systems (and hence a diminished ability to take up water and nutrients)
• Reduced vine growth
• Lower yields

Question 10

Describe what happens if there is too little Calcium in the soil? Is this common?

Answer 10

Calcium is important for plant cell structure, and for photosynthesis

Insufficient levels

• are rare
• Negative influence on fruit set

Question 11

What is Magnesium essential for? Where is it found?

Answer 11

• Magnesium is found in chlorophyll
• Key role in photosynthesis

Too little results in:

• Reduced grape yields
• Poor ripening

Question 12

What effects nutrient availability in soil?

Answer 12

• Soil pH

Question 13

What is chlorosis? What causes it?

Answer 13

• Chlorosis is a condition in which photosynthesis stops thus leaves turn yellow. Neg impact on grape ripening/ yields.
• Chlorosis results from a high PH level in soil which affects the “availability” of iron for the vine

Question 14

What must happen before the vine can take up organic nutrient compounds (found in and added to soils)? How does this happen?

Answer 14

• Need to be converted into inorganic compounds
• Organisms/microbes that live in the soil feed on the organic matter and convert it into available forms (a process called mineralisation).

Question 15

Describe the important physical elements in soil for viticulture?

Answer 15

• Texture - means the proportions of sand/silt/clay

- Structure - how the soil “crumbs” which determines water drainage, root structure and workability.

Question 16

What soils are typically less fertile and thinner: soils on slopes or soils on plains/valley floors?

Answer 16

Slopes

Question 17

Describe sand, clay, silt, loam

Answer 17

• Make up the soil texture
• Sand has larger particles, drains freely, does not have good nutrient holding capacity. But the particle size makes it easy for roots to grow.
• Clay has small particles, retains water and nutrients - the soil has a fine texture. Its hard for the roots to penetrate, and difficult to cultivate
• Silt has properties between sand and clay.
• Loam has a combination of sand, clay and silt, plus additional gravel particles which give it good drainage, but lower its nutrient retention capacity.

Question 18

What types of layers make up the soil of a particular vineyard site?

Answer 18

• Different layers formed at different periods of time, each of which may have a different texture, structure and characteristics
• The sediment in the soil may not be the same as the bedrock underneath; for example, over time the sediment may have been transported by water, winds, glaciers or gravity (down-slope).

Question 19

What are the two main functions of soil?

Answer 19

• Supports the vines’ roots

- Medium from which vines take up water and nutrients.

Question 20

Explain how can you adjust the structure of soil to increase nutrient levels

Answer 20

By adding humus / compost / fertiliser
Humus is organic matter, spongy, partially decomposed by microbes, can retain water and nutrients. It can help to bind a sandy soil, or loosen a clay soil.

Question 21

What is soil texture?

Answer 21

The texture of the soil describes the proportions of the mineral particles of sand, silt and clay.

Question 22

What is soil structure?

Answer 22

• The structure of the soil describes how the mineral particles in the soil form aggregates (crumbs)
• The size, shape and stability of these aggregates determine water drainage, root growth and workability of the soil.

Question 23

Describe the soil structure of soils that have a very high clay content.

Answer 23

• Sticky / fine structure

- Hard for vine roots to penetrate and challenging for soil cultivation.

Question 24

What is humus? What’s its texture? What does it help with?

Answer 24

• Humus is organic matter - partially decomposed plant material.
• It has a spongey texture, large surface area and is able to adsorb water and nutrients.

Question 25

Explain suitability of soil for viticulture? Give an example.

Answer 25

Determined by

• Soil texture
• Soil structure
• how far the roots are able to penetrate
• Climate suitability

Example:
Sandy soils might be suitable for regions with high rainfall levels
Sandy soils might be suitable if the vine can go deep to find water and nutrients
The texture of the soil can be adjusted to ensure the right nutrients area available.