Soil Flashcards
Why is soil important for the vine?
It anchors the vine and provides nutrients for growth.
Define soil’s origin and properties.
The result of physical, chemical, and biological processes acting on organic substances and inorganic weathered rock (mineral matter) that accumulate on Earth’s surface.
It is porous, containing water and air.
What are the general proportions of soil components?
40-60%
Mineral Matter
20-50%
Water
10-25%
Air
Remainder
Organic
How has old world winemaking influenced the perception of soil fertility and viticulture?
Experiential learning has shown that stony, low fertility soil with good drainage restricts vegetative growth, warms quickly and radiates heat. The latter attributes are particularly important in cooler, damper environments.
What are the physical properties of soil?
Texture
Structure
Color
Water Availability and Drainage
Air
What are the chemical properties of soil?
Soil Acidity/PH
Nutrient Status
What are the biological properties of soil?
Organic Matter
Humus
Micro-organisms
Organisms
What type of soil can vines grow in?
A wide range that can be ameliorated to provide sufficient nutrients to the vine.
What is an important consideration when planting a vine regarding the availability of water, nutrients, etc.?
That the rootstock is appropriate to the soil.
What properties of the soil do texture and structure affect?
Water Availability and Drainage
Nutrient Availability
Aeration
Root Growth
Erosion
Ease of Cultivation
What are common soil particles and their relative diameter, in millimeters?
Clay
<0.002mm
Silt
0.002-0.02mm
Fine Sand
0.02-0.2mm
Sand
0.2-2mm
Gravel / Grit / Stones
>2mm
What is a Colloid?
A particle smaller than 0.001mm (1 micrometer, 1μm)
What is Soil Texture?
A measure of the proportions of inorganic clay, silt and sand that soil contains.
These particles are graded by their size.
What are the classifications of soil texture and their parameters?
Sand: 5% Clay particles
Loam: 25% Clay particles
Clay: 50% Clay particles
Which soils are heaviest and which are lightest?
Clay soils are heaviest.
Sandy soils are lightest.
Which soils are typically preferred for viticulture?
Loam soils.
Which soils hold more water content and why?
Heavy soils due to their high clay or silt content. The smaller particles hold water tightly on their surface..
Which soils hold less water content and why?
Light soils due to their high sand and gravel content. The larger particles create space that allows water to drain freely.
What are the benefits and risks of using coarser soils?
The soil offers good drainage which can benefit vines in damp regions, though whatever water remains is easily accessible. They do not typically retain nutrients. In some places, both water and nutrition can be controlled.
Regarding Microclimate, why is the proportion of clay in a soil important?
1) Clays have a great capacity to bind and hold water and nutrients.
2) Clay particles are negatively charged, so they can hold more nutrient elements (minerals).
3) The water absobed by clay may not be available to the vine.
4) Clay tends to heat up slower in spring and be cooler year round due to its water retention.
Viticulturally, why is the proportion of clay in a soil important?
1) Clay is slippery and expands when wet but shrinks when it dries. This can crack the Clay which forces the water out and could hurt the vine’s roots.
2) Clay becomes sticky when wet, making it difficult to work and drive on with machinery.
3) The structure of clay deteriorates when it is worked.
4) Dry clay soils are hard and solid, making root penetration difficult.
When does the presence of clay best benefit a vine?
When there is a proportion of larger particles to aid aeration and drainage. Mixing Clay with larger particles pushes the soil type closer toward a preferred Loam style.
Describe the characteristics of predominantly Sandy soils.
Coarse textured
Allow easy root penetration
Low nutrition and high drainage
May collapse under excess water
Heat up more quickly in Spring and are generally warmer than Clay soils
Describe the characteristics of soil that is predominantly Clay and Silt.
Fine textured
Impede root growth
High nutrition, water retaining
More stable than Sandy soils
Describe the characteristics of Loam soils.
A largely balanced mix of Clay, Silt, and Sand.
Freely draining with large water retention capacity.
Possess some of the drainage of Sandy soils and a good proportion of the water and nutrient retaining Clay soils.
Fertile and can encourage too much vegetative growth.
True or False
Particles greater than 2mm are excluded from soil texture measurements.
True, though Gravel and larger stones have important effects on soil.
What effects do Gravels have on soils?
In the soil they reduce water retention and improve drainage
On the soil they reduce erosion and aid soil moisture conservation
What effect does Gravel have on Microclimate?
They store heat during the day and radiate it back into the canopy at night.
What is Soil Structure?
The Friability of the soil.
How clay, silt, and sand clump together to form aggregates and how readily the aggregates crumble.
How well the soil forms lumps and crumbs.
What are the characteristics of well structured soil?
Roots can easily penetrate
Water and air can access the soil
Resistant of wind and water erosion
What is a Soil Aggregate?
Groups of soil particles bound more strongly to each other than to surrounding particles. These aggregates form a matrix that creates the overall Soil Structure.
Why is organic matter important to the formation of Soil Aggregates and how does the process work?
Aggregates start to form when Colloidal Clay binds with organic matter such as water, microbial filaments, and organic secretions.
These then bind with silt, sand, and other organic particles to form Aggregates.
What is the effect of organic matter on Friability?
Organic matter improves Friability. The ideal level of organic matter in a soil is 3-10%, considered moderate to high.
What is the ideal level of Friabaility of a soil?
Aggregates up to 2cm that crumble easily increases the rate at which water and air move through soil and subsoil. Roots can also penetrate with ease.
What is the correlation between Friability and the access roots, water, and air have to a soil?
Direct positive correlation.
More Friability means more root, water, and air penetration.
Less Friability means less access as the Aggregates do not crumble easily.
What influences soil structure?
Organic matter
Earthworms and other soil organisms
Wetting and drying
Freezing and thawing
Presence of plant roots
Cultivation and other soil management practices
Texture
Drainage
Compaction
How can the stability of a soil be improved?
The addition of more organic matter
The activity of soil organisms
How do earthworms improve Soil Stability?
They help bind soil particles into stable aggregates
What can poor Soil Structure lead to?
Capping/Crusting: the hardening of the soil’s surface
Puddling: rainwater stays on the soil surface, causing extensive erosion
Sieving: Clay particles are carried down with the water through the soil, sometimes forming a layer that prevents drainage and aeration
Why is it important for air to penetrate into the soil?
The growing tips of vine roots and aerobic soil microbes require oxygen to grow
Why is water penetration important?
Root tips require water to obtain nutrients. Too much, however, will drown the tips and cut off their air supply.
What is Waterlogging?
inadequate drainage that decreases soil aeration, thus restricting root growth and the depth at which roots can reach.
Prolonged waterlogging can kill roots from lack of air.
How does subsoil help vines in regions with dry summers cope with the lack of water?
The roots can tap into water stored in the subsoil late in the season.
What soils are most fertile?
Loamy soils.
Those with a balance of freely draining soil structure and large water holding capacity.
How much water do vines need during the growing season?
500mm (more in hot conditions)
The rate of vine growth in many wine regions is largely determined by what?
The availability of water.
Why is aeration essential in soil?
Provides oxygen to aerobic organisms and suppresses growth of anaerobic organisms
Removes carbon dioxide and other waste gases formed by breakdown of organic matter and by plant roots
Provides roots with oxygen essential for respiration and growth
In what soils can air movement be severely restricted?
Poorly structured clay soils
Heavily compacted soils
Aeration is affected by the ability of the soil to do what?
Drain effectively
What determines a soil’s ability to drain water effectively?
Soil structure and depth of impermeable soil layers
Vines do not grow well on poorly drained soils. Why?
The soils are cooler and take longer to heat in the spring.
They restrict root growth, leading to a reduced resistance to drought and an increased risk of mineral deficiency
How does drainage affect machinery in the vineyard?
Poor drainage reduces the bearing capacity of a soil.