Ch.2 Soil

Question 1

What are the 4 components of soil, and, generally speaking, in what proportions are they found?

Answer 1

1. Mineral matter (40-60%)
2. Water (20-50%)
3. Air (10-25%)
4. Organic substances (remainder)

Question 2

On what evidence is the lore that vines do well on poor soils based on?

In what kind of environment is this more apparent?

Answer 2

• Poor soils = low fertility, stony soils.
• Low fertility = barely-adequate nutrient supply.
• Low nutrient supply restricts vegetative growth, and stony soils drain well, warm quickly and radiate heat.
• These attributes are more important in cooler, damper environments.

Question 3

What is the difference between soil texture and soil structure?

What can these differences be likened to?

Answer 3

TEXTURE: measure of proportions of inorganic clay, silt and sand particles, graded by size.

STRUCTURE: measure of the friability of soil, i.e. the way the textural particles clump together to form aggregates, and how readily these aggregates crumble into smaller fragments.

TEXTURE = bricks and mortar

STRUCTURE = rooms and corridors

Question 4

Identify the 5 common categories of soil texture particles and rank them from smallest to largest:

Answer 4

Clay: <0.002mm diameter

Silt: 0.002 - 0.02mm

Sand: 0.02 - 2mm

Gravel / Grit / Stones: >2mm

Boulders: >600mm

Question 5

Sands contain up to __% of clay particles.

Loams contain up to __% of clay particles.

Clays contain more than __% of clay particles.

___ soils are preferred for agriculture.

Answer 5

5%

25%

50%

Loam

Question 6

In terms of water-retention and drainage capability, what are the differences between fine/medium-textured soils and coarser-textured soils?

Answer 6

• Fine/medium-textured soils, e.g. clay / clay loams, offer better water and nutrient rentention, but lesser drainage capabilities.
• Coarser-textured soils, e.g. sand, offer better drainage, but poorer ability to retain nutrients and water.

Question 7

What are some pros/cons of clay soils in regards to viticulture?

Answer 7

PROS:

• Great capacity to bind and hold both nutrient elements and water.
• Can expand like a sponge to absorb more water.

CONS:

• Much of the water remains bonded to clay particles, so may not be available to plants.
• Wet clay soils are difficult to work.
• Dry clay soils are hard and solid, making root penetration difficult.

Question 8

What needs to be done to optimise the benefits of clay soils?

Answer 8

Clay needs to be mixed with larger soil particles, to move the texture more towards that of loam soils.

Question 9

What are some benefits of soils containing gravel/larger stones?

Give 2 examples where such benefits are clearly seen:

Answer 9

• Improve drainage and reduce water-holding capacity.
• Reduce erosion risk.
• Aid in soil moisture conservation.
• Store heat during the day, radiate it back to plants during the night.

Chateauneuf-du-Pape, Southern Rhône, France (Galet stones).

Mosel, Germany (Blue slate soils).