Soil Textures Ect. Flashcards
What are the main physical properties of soil
- texture
- structure
- bulk density
- porosity
- structural stability
What is a typical soil made up of?
45%minerals 5% organic matter 25%water 25%air
What is soil texture?
Determined by the sizes and proportions of the mineral particles in the soils (sand, solt, clay)
What is the soil structure?
Built up by the aggregation of textural particles under the influence of agents such as organic matter fauna, root pressure, wetting and drying
What type of soils have a high buffering capacity?
Clays
What two things hold clay together into a good structure?
Organic matter
Calcium
What is the key difference between silt and clay?
Clay will polish, silt wont
What doe the soil structure have the biggest impact on?
Permeability
What is soil stability improved by?
The presence of
Calcium carbonate
Iron oxides
Hummus
What publications are there to assist with soil structural examination?
Think soils
VESS system
Why is surface capping a problem
- hard for seedling emergence and water infiltration
- increases risk of run off
- deposition of soil at field edges and on roads
Solutions to surface capping?
Avoid production of fine seed beds
Retain residues in surface and incorporate organic matter
Break the cap with ring rolls or light harrows
What is the problem with compaction
Restricts rooting, aeration and drainage
Deep pans may be formed
Patching can form shallow pans
Solutions to compaction
Problem with anaerobic layers
Often blue grey and smells
Roots cannot penetrate and nitrogen is lost
Solutions for anaerobic layers
Improve drainage within and below layers
A vigorously growing crop can improve the structure
What will influence the rate of loss of organic matter
- soil temperature
- aeration
- availability of water
Soil acidity will reduce the rate of loss
What is the C:N ratio a soil microorganism needs to stay alive
30:1
What is the standard conversion between SOM to SOC
0.58
What is the nitrification rates
Measuring the activity of those species involved in the conversion of ammonium to nitrate
Several functions healthy soil performs
Regulating water
Sustaining plant and animal life
Filtering and buffering potential pollutants
Cycling nutrients and carbon storage
Physical stability and support
