3.3 Nutrients

Question 1

Where does the vine acquire its nutrients?

Answer 1

Soil

Question 2

What factors do nutrients influence?

Answer 2

• Yield

- Grape composition

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)

Question 6

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

Answer 6

Excessive vegetative growth

• Sugars 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

Question 8

What is Potassium essential for?

Answer 8

• Vine growth

- Regulates the flow of water in the vine

Question 9

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

Answer 9

• Problems in the uptake of magnesium, which may lead to reduced yields and poor ripening.
• Leads to high potassium levels within the grapes (wine quality lowers, as high levels of potassium in the grape must are linked to high pH)

Question 10

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

Answer 10

• Low sugar accumulation in the grapes
• Reduced grape yields
• Poor vine growth in general

Question 11

What is Phosphorus essential for?

Answer 11

• Photosynthesis

Question 12

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

Answer 12

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

Question 13

How much Phosphorus do vines typically need? Where do they get this?

Answer 13

• Vines need only a small amount

- Usually there is enough phosphorus naturally present in the soil.

Question 14

What is Calcium essential for?

Answer 14

• Structure of plant cells

- Photosynthesis

Question 15

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

Answer 15

• Negative influence on fruit set

- Rare

Question 16

What is Magnesium essential for? Where is it found?

Answer 16

• Magnesium is found in chlorophyll

- Key role in photosynthesis

Question 17

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

Answer 17

• Reduced grape yields

- Poor ripening

Question 18

What affects nutrient availability in soil?

Answer 18

• Soil pH

Question 19

What is chlorosis? What causes it?

Answer 19

• This is a condition in which leaves turn yellow and photosynthesis stops, so grape ripening and yields are negatively affected as a result.
• Lack of iron in the soil (high pH)

Question 20

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

Answer 20

• Need to be converted into inorganic compounds

- Organisms that live in the soil feed on the organic matter and convert it for the vine

Question 21

What is mineralisation?

Answer 21

The process by which organisms that live in the soil (such as bacteria, fungi, earthworms, etc.) feed on the organic matter and convert it into available forms

Question 22

What types of soil texture are good at holding nutrients? Bad?

Answer 22

• Good: clay

- Bad: sandy

Question 23

What can increase the soil’s ability to hold nutrients?

Answer 23

Humus

Question 24

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

Answer 24

Slopes

Question 25

What is soil? What is it comprised of?

Answer 25

• Soil is the upper layer of the earth
• Typically made up of geological sediment, organic remains in the form of humus, and the pores in between the sediment that contain water and air.

Question 26

Where does Sediment come from?

Answer 26

Sediment comes from the weathering of bedrock (solid rock).

Question 27

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

Answer 27

• 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 28

What are the two main functions of soil?

Answer 28

• Supports the vines’ roots

- Medium from which vines take up water and nutrients.

Question 29

Describe Clay soil. How does this affect its ability to hold water & nutrients?

Answer 29

• Finely-textured
• Very small particles (large surface area compared to their volume)
• Very effective at holding water and nutrients

Question 30

Describe Sand soil. Describe how these characteristics affect the soils ability to hold water and nutrients.

Answer 30

• Loosely-textured
• Relatively large particles with small surface area compared to their volume
• Limited capacity to hold water
• Easy drainage
• Poor at retaining nutrients.
• Workable and easy for vine roots grow through

Question 31

Describe Silt soil.

Answer 31

Silt has particles of intermediate size and its properties sit between that of clay and sand.

Question 32

What is Loam soil? Describe its characteristics when it comes to drainage and water/nutrient holding capacity.

Answer 32

• ‘Loam’ describes a soil that has moderate proportions of clay, silt and sand.
• May contain a proportion of larger rock fragments, such as gravel or pebbles (larger than gravel).
• Good drainage
• Lower water- and nutrient-holding capacity

Question 33

What is soil texture?

Answer 33

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

Question 34

What is soil structure?

Answer 34

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

Question 35

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

Answer 35

• Sticky
• May form aggregates that are hard for vine roots to penetrate and challenging for soil cultivation.
• The vines’ roots may be limited to cracks or gaps between the aggregates.

Question 36

Describe the soil structure of soils that have are high in sand or larger particles such as gravels or pebbles.

Answer 36

• Very loosely structured
• Need some clay to help bind them together.
• Humus helps to bind soils together and can help soils to retain water and nutrients.

Question 37

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

Answer 37

• Humus is organic matter in the soil that is formed by the partial decomposition of plant material by soil microbes and earthworms.
• It has a spongey texture, large surface area and is able to adsorb water and nutrients.

Question 38

What does the suitability of the soil for viticulture depend on? Give an example.

Answer 38

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

Example:
Very sandy or stony soils have poor water and nutrient-holding capacity, but may prove suitable if the vine roots are able to grow freely and deeply, giving a large area over which the vine can obtain water.