The Growing Environment: Nutrients and Soils

Question 1

From where does the vine acquire its nutrients?

Answer 1

Soil

Question 2

What factors do nutrients influence?

Answer 2

Vine health
Grape 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 proteins and chlorophyll (required for photosynthesis)

Question 6

What happens if there is too much/too little nitrogen in the soil?

Answer 6

Too much:
- 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

Too little:
- Reduced vigour
- Yellowing of vine leaves
- Problematic for fermentation

Question 7

What is Potassium essential for?

Answer 7

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

Question 8

What happens if there is too much/too little potassium in the soil?

Answer 8

Too much:
- 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)

Too little:
- Low sugar accumulation in the grapes
- Reduced grape yields
- Poor vine growth in general

Question 9

What is phosphorus essential for?

Answer 9

Photosynthesis

Vines need only a small amount. Usually there is enough phosphorus naturally present in the soil.

DEFICIENCY = poorly developed root systems, reduced vine growth, poor yealds

Question 10

What is calcium essential for?

Answer 10

Structure of plant cells, and photosynthesis

Question 11

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

Answer 11

• Negative influence on fruit set

Question 12

What is Magnesium essential for?

Answer 12

• Magnesium is found in chlorophyll
• Key role in photosynthesis

Question 13

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

Answer 13

• Reduced grape yields
• Poor ripening

Question 14

What affects nutrient availability in soil?

Answer 14

Soil PH

Question 15

What is chlorosis? What causes it?

Answer 15

• 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 available iron in the soil (high pH)

Question 16

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

Answer 16

• 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 17

What is mineralisation?

Answer 17

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 = inorganic (compounds that not contain CARBON)

Question 18

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

Answer 18

• Clay = good at holding nutrients and water (very small particles)
• Sandy = poor at holding nutrients (relatively big particles) / roots can easily grow through

Question 19

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

Answer 19

Humus

Question 20

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

Answer 20

Soils on slopes

Question 21

Describe Silt soils

Answer 21

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

Question 22

Examples of soils:

Answer 22

Clay = Pomerol (Crasse de fer)
Sand = Colares (Chao de Areia)
Gravel = Gimblett Gravels , Hawkes bay

Question 23

Loam soils

Answer 23

• ‘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 24

What is soil texture?

What is soil structure?

Answer 24

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

• 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 25

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

Answer 25

• 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 26

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

Answer 26

• 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 27

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

Answer 27

• 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 28

What does the suitability of the soil for viticulture depend on?

Answer 28

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