Unit Title:
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Co-Requisites:
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Unit Assessor:
Soil Food Web Interactions and Benefits to Plant Production
Professional Development Unit (full fee paying)
Nil
Nil
Internal
15th June – 26th June 2009
Adjunct Professor Elaine R. Ingham
Ph: (02) 6622 5150
Aims
This unit examines the function of each major soil organism group (bacteria, fungi,
protozoa, nematodes, microarthropods, mycorrhizal fungi) and their importance to plant
production. Interactions of these organisms with each other and their influence on
nutrient cycling, nutrient retention, disease suppression and soil structure will be
examined in addition to how life history strategy impacts plant production. How the
different functional groups of organisms are affected by chemical applications such as
pesticides and fertilizers will also be introduced.
Objectives
On completion of this unit, students should be able to:
1. Understand the functions of each major group of organisms in soil
2. Understand the interactions of the different functional groups in the soil
3. Understand how soil organisms influence nutrient cycling and nutrient retention,
4. Understand how disease-causing organisms can be influenced by other groups of
organisms in the soil,
5. Understand how soils structure is built by soil biology,
6. Demonstrate management of soil biology to change or influence desired
functions,
7. Demonstrate an appreciation of management practices which alter soil habitats
8. Demonstrate an understanding of different methods to assess each group of
organisms in soil
9. Demonstrate an understanding of plant responses to improving soil conditions
Handbook Entry
The functions of each group of soil organisms, their interactions and how that affects
disease, nutrient retention, nutrient cycling, residue decomposition, and soil structure are
examined. Methods to assess function and interactions are explored. Management of
each soil biology group and how each group affects plant responses are introduced.
Syllabus
This unit will cover the following topics (not necessarily in the order presented) which
will be dealt with in lectures, tutorials and field trips;
 Soil Bacteria
o Biomass, activity and methods to assess
o Functional Groups and interactions with soil
o Aerobic, Anaerobic, Facultative distinctions and relationship to plant
growth
 Soil Fungi
o Biomass, activity and methods to assess
o Functional groups and interactions in soil
o Relation to carbon cycle
 Soil Protozoa
o Numbers, functions, methods to assess
 Soil Nematodes
o Different functional groups
o Enumeration, activity
 Soil Microarthropods
o Different functional groups
o Enumeration, activity
 The biologically based nitrogen cycle
o N-fixers
o N retention in bacteria and fungi
o Predation and mineralization
o Nitrification
o De-nitrification
 The complete carbon cycle (beyond simple soil organic matter)
o Carbon dioxide and energy: photosynthesis
o Plant forms of C; release from roots
o The driver of nutrient uptake
o Water interactions
o Time of year changes in carbon forms and the effects on organisms in the
root system
o What determines storage versus uptake functions
 Mineral nutrition and retention in biology in soil
o What holds Ca in soil
o What form of Fe, and what determines the form?
o Soil nutrient reserves versus plant available nutrients versus nutrients in
plants: Extraction methods and what they tell you
 Soil Structure
o Which organisms form which kinds of aggregates and pore structures in
soil
o Methods to determine soil structure, which size fractions different
organisms are found in
o Root depth: much deeper than current agricultural understanding
o Water retention and soil biology
Recommended Reference Materials
Ingham. 1999. Soil Biology Primer. USDA
Sylvia 1995. Principles and Applications of Soil Microbiology. Prentice Hall.
Student Assessment Requirements
Assessment
2,000 word report on
soil food web structure,
function and nutrient
cycling in a chosen
ecosystem
Time Required
After first
week of
class
Weighting
50%
Objectives
1, 2, 3, 4, 5, 9
Attendance/Participation
in field trips
Each day
5%
All
Final Exam
End of week 2
45%
6, 7, 8, 9
To obtain a pass in this unit, participants must obtain %50 overall, and satisfactorily
complete all assessment items.
Late assignments will be penalized at a rate of 10% of the available mark for each day
late unless an extension is granted.
Drunken or other irresponsible behavior whilst involved in field or laboratory work may
also be a reason for failure of the unit regardless of marks.
Active participation is expected in all field excursions. Correct attire must be worn and
equipment for assessing field parameters must be brought to all field sessions.