The Growing Environment: Nutrients and Soils Flashcards
From where does the vine acquire its nutrients?
Soil
What factors do nutrients influence?
Vine health
Grape yield
Grape composition
Do vines require high or low levels of nutrients?
Low
What are the 5 most important nutrients for vines?
- Nitrogen
- Potassium
- Phosphorus
- Calcium
- Magnesium
What is nitrogen essential for?
- Vine growth
- Major impact on vine vigour and on grape quality.
- Component of proteins and chlorophyll (required for photosynthesis)
What happens if there is too much/too little nitrogen in the soil?
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
What is Potassium essential for?
- Vine growth
- Regulates the flow of water in the vine
What happens if there is too much/too little potassium in the soil?
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
What is phosphorus essential for?
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
What is calcium essential for?
Structure of plant cells, and photosynthesis
What happens if there is too little calcium in the soil?
- Negative influence on fruit set
What is Magnesium essential for?
- Magnesium is found in chlorophyll
- Key role in photosynthesis
What happens if there is too little magnesium in the soil?
- Reduced grape yields
- Poor ripening
What affects nutrient availability in soil?
Soil PH
What is chlorosis? What causes it?
- 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)
What must happen before the vine can take up organic nutrient compounds (found in and added to soils)?
- Need to be converted into inorganic compounds
- Organisms that live in the soil feed on the organic matter and convert it for the vine
What is mineralisation?
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)
What types of soil texture are good at holding nutrients? Bad?
- Clay = good at holding nutrients and water (very small particles)
- Sandy = poor at holding nutrients (relatively big particles) / roots can easily grow through
What can increase the soil’s ability to hold nutrients?
Humus
What soils are typically less fertile and thinner: soils on slopes or soils on plains/valley floors?
Soils on slopes
Describe Silt soils
Silt has particles of intermediate size and its properties sit between that of clay and sand.
Examples of soils:
Clay = Pomerol (Crasse de fer)
Sand = Colares (Chao de Areia)
Gravel = Gimblett Gravels , Hawkes bay
Loam soils
- ‘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
What is soil texture?
What is soil structure?
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.
Describe the soil structure of soils that have a very high clay content.
- 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.
Describe the soil structure of soils that have are high in sand or larger particles such as gravels or pebbles.
- 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.
What is humus? What’s its texture? What does it help with?
- 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.
What does the suitability of the soil for viticulture depend on?
- Soil texture
- Soil structure
- How far the roots are able to penetrate
- Climate suitability
