Physical Soil Quality Indicators

1
Physical Soil Quality Indicators
2
Physical Soil Quality Indicators

• Soil Structure
• Aggregate Stability
• Bulk Density/Compaction
• Soil Pores
• Permeability
• Infiltration
• Surface Crusting
• Available Water Holding Capacity

3
Soil Structure

• Definition
• The naturally occurring arrangement of soil
  particles into secondary units or peds.
• Why is it important?
• Infiltration/Permeability
• Soil Erosion
• Root penetration
• Others?

4
(No Transcript)
5
Structureless
Good Structure
6
(No Transcript)
7
Factors Influencing Soil Structure

• Surface development factors
• Biological activity
• Organic Matter
• Tillage
• Subsurface development factors
• Texture
• Shrink-swell, wetting drying cycles
• Others?

8
Aggregate Stability

• Definition
• The ability of soil aggregates to resist
  disruption.
• Why is it important?
• Good Aggregate Stability reduces erosivity
• Facilitates water movement into and through soil
• Plant root growth
• Others?

9
(No Transcript)
10
(No Transcript)
11
Factors Influencing Aggregate Stability

• Organic Matter content
• Clay Content
• Tillage
• Others?

12
Bulk Density/Compaction

• Definition
• Bulk Density is the weight of a given volume of
  soil
• Compaction is the reduction of pore space
• Why is it important?
• Root growth and development
• Water and air movement
• Others?

13
Compacted
14
(No Transcript)
15
Compacted zone
16
Soil Pores

• Definition
• Air or water filled voids in the soil.
• Why is it important?
• Infiltration
• Permeability
• Root Penetration
• Others?

Soil
45 Mineral
50 Pore Space
5 Organic
17
Factors Influencing Soil Pores

• Tillage
• Compaction
• Plants and Animals
• Others?

18
Soil at Bottom of Soil Core
Earthworm channels
18 Years No-till
Conventional Tillage
19
(No Transcript)
20
(No Transcript)
21
Water Movement Through Soil

• Video Presentation

22
Soil Permeability

• Definition
• The ease with which fluids or gasses can flow
  through soil.
• Why is it important?
• Leaching of fertilizer or pesticides
• Slow permeability increases water erosion
• Water retention in structures (dam or pond)
• Others?

23
(No Transcript)
24
(No Transcript)
25
Factors Influencing Permeability

• Texture
• Compaction
• Porosity
• Structure
• Others?

26
Infiltration

• Definition
• The process of water entering the soil from the
  surface.
• Why is it important?
• Soil as storage medium for water
• Good infiltration reduces erosion, runoff, and
  ponding.
• Others?

27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
Infiltration
0.1 in/min
5 in/min
88 Water Stable Aggregates
35 Water Stable Aggregates
31
Factors Influencing Infiltration

• Tillage and pore disruption
• Compaction
• Surface Crusting
• Biological Activity (earthworms, etc.)
• Soil structure
• Others?

32
Earthworm Burrows
middens
Middens piles of residue around the mouth of
earthworm burrows.
33
Surface Crusting

• Definition
• Thin layer on the soil surface that restricts
  water and air entry and seedling emergence.
• Why is it important?
• Reduces infiltration
• Increases Runoff
• Others?

34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
Factors Influencing Surface Crusting

• Organic Matter
• Residue Cover
• Aggregate Stability
• Rainfall Intensity
• Others?

38
Available Water Capacity (AWC)

• Definition
• The amount of water that is between field
  capacity and permanent wilting point.
• Why is it important?
• Water supply for plants between each rainfall or
  irrigation
• Others?

39
(No Transcript)
40
Factors Influencing AWC

• Organic Matter
• Texture
• Bulk Density
• Others?

41
(No Transcript)