Soils 2 Flashcards
Darker soils indicate…
More organic matter
Which layer accumulates iron, clay, aluminum, and organic compounds?
Subsoil (B)
Which layer is present with pronounced leaching?
E
How many soil orders are there?
12
What causes red color in soil?
Oxidation of iron
Which soil is most fertile?
Sedimentary
Underlying soil gets ___________ on slopes.
exposed
Excessive soil moisture leads to…
excessive vegetative growth
increased fruit acidity
diluted fruit and wine flavors
fruit rots are increased by berry splitting
disease conditions in dense canopies of vigorous vines
Insufficient water leads to…
drought stress
insufficient vine growth
reduced yields
impaired fruit ripening
sun-burning of fruit
Which soils are more prone to frost?
rock soils
_____ soil absorbs and loses heat faster than ______ soil
Dry soil absorbs and loses heat faster than wet soil
Can white or light color soils reflect more heat and light?
Yes, up to 50%
Does dark soil increase soil temperature?
Yes, as little as 5% increase in soil temperature
How does slope affect vine exposure to radiation?
It increases exposure by changing the orientation to the sun
Root growth is delimited by…
bed rock
impenetrable clay
cemented pans
inhospitable environment (competition)
chemical toxicity
waterlogging
Why do roots not grow at the surface?
High temperatures
cultivation
Roots are often in the top______ (even in deep soils)
1 meter
What is considered a shallow soil?
30 cm
What is considered a deep soil?
200 cm
Is soil with <25% clay good or bad?
Good; water with high clay has less available water
Is soil with >25% clay good or bad?
Not so good;
Leads to compaction, shrink-swell, damage and/or asphixiateroots, and waterlogging
Soils can be described in terms of its …
Depth, parent rock origin, texture, hydrology
and organic matter, CEC, microbial and other invertebrate fauna density and diversity
Humus
OM that has broken down as far as it can go
Present at depth in soil
A soil devoid of humus cannot be penetrated by roots
Humus is formed by:
non degradation of plant lignin (carbon)
activity of soil microorganisms
Soil needs humus to …
Remain fertile, Sustain the biological life of the soil organisms
What is the role of soil water?
Enables the transfer of nutrients from soil to the plant roots
mitigates soil temperature
contributes to vine vigor
sustains soil microorganisms that increase transfer of nutrients into roots
aides in ion transfer and interdependent with CEC
Cation exchange capacity (CEC)
the soil’s ability to attract/hold positively charged nutrient cations
Influences soil structural stability, nutrient availability, soil pH and the soil’s reaction to fertilisers and other ameliorants
The level of CEC depends on …
percentage and mineralogy of clay it contains
amount of OM
pH
The 4 major exchangeable cations in soils are…
Calcium Ca2+
Magnesium Mg2+
Potassium K+
Sodium Na+
Clay has a low or high CEC?
high
High base saturation means…
…more sites are occupied by these (basic) ions and less by H+ ions (acidic)
High base saturation correlates with…
high pH
How do cover crops add N to soil?
Leguminous cover crops can ‘fix’ atmospheric N
As soil pH increases, _______ and ________ becomes more available?
calcium and magnesium
As soil pH decrease, ________ and ________ become more available but causes decreased availability of other essential nutrients.
aluminum and iron
If the soil has more cations like Ca2+ and Mg2+, the soil likely has a …
higher pH
A soil pH may be too low due to …
Al3+ and Fe3+ oxides
intensive farming
ammonium based fertilizers
organic matter
A soil pH can be raised by….
Applying lime (calcium)
How much lime and/or organic matter to add to a soil?
on clay soils, 1 T/ha raises pH by 0.1
on lighter soils, 1 T/ha will raise pH by 0.4
Lime-induced chlorosis
Symptoms- yellow leaves in spring
Solution- lime resistant rootstock
In high pH soils, unavailability of Fe3+ due to competition from excess Ca2+ ions, which affects the development of chlorophyll.
Old world perspectives on wine
Soils are important in affecting wine quality
properties are often small parcels due to inheritance
irrigation is typically not done
Long experience in one sit gives a hierarchy of “crus”
soil type can be used for defining appellation regions
New world perspectives on soil and wine
Soils are unimportant in affecting wine quality
properties are often large
irrigation is widely used
limited historical experience
soil mapping now more common
A good soil has…
Water holding capacities
>enough but not too much
>easily extracted by roots
>resistance to runoff
Root penetration
>large enough zone to get water and nutrients
>not too shallow
>deep (if no irrigation)
>resistance to compaction
Tools to improve soil….
drainage
ripping
liming
adding OM
Tools to prevent deterioration…
Avoid compaction
Fertilize as needed
Mulch to retain water
Do not overwater
