ASPAC | Pacific network of soil laboratories: 1st meeting. Brisbane, Australia, 17 - 18 October 2019. Presenter: Phil Moody

1. Soil analysis methods and interpretation
Phil Moody
University of Queensland
p.moody@uq.edu.au

2. • Why do soil analysis?
• What do your clients expect?
• Which soil analyses?

3. • Why do soil analysis?
Inventory of soil resources
(e.g., national soil surveys)
• Large numbers of samples
• Requirement to undertake numerous
‘standard’ analytical methodologies
using a wide range of instrumentation
Identification of soil constraints
to crop production
• Small number of targeted samples
• Opportunity to use a smaller suite of
soil analytical methods
• Opportunity to undertake targeted
analyses, depending on the soil problem

4. • What do your clients expect?
 Quality-assured soil test results
(Repeatable soil test results that are in agreement
with results from other QA certified labs)
 Interpretive guidelines for the soil tests
(Clients value this service, and it enhances the lab’s
reputation as a valuable asset)

5. • Which soil analyses?
• Soil pH
• Electrical conductivity (EC)
• Soil organic carbon
• Available (extractable) phosphorus
• Available (exchangeable) potassium
SEALNET is focussing on QA/QC and interpretive guidelines for the
following soil analyses
Are these analyses the most useful for the Pacific
region to focus on for QA/QC and interpretive
guidelines?
Are there others?

6. What are the ‘problem soils’ likely to require
diagnostic soil analyses?

7. Are there other ‘problem soils’ in the
Pacific region?
• Coral sands
• Volcanic ash soils

8. What are the constraints of these
‘problem soils’?

9. Are there other soil constraints in the
Pacific region?

10. Problem Soils Constraints
Acid sulfate soils Acidity
Heavy metal toxicities
Peat soils Acidity
Multiple nutrient deficiencies
Possible high P fixation
Waterlogging
Sandy soils Acidity (high risk of acidification)
Low nutrient retention
Low plant available water
Compaction (fine sands+silt)
Skeletal soils Low nutrient retention
Low plant available water
Susceptibility to erosion
Contaminated and disturbed soils Compaction (restricted particle sizes)
Hard-setting
Heavy metal toxicities
Coral sands Alkalinity?/sodicity?/salinity?
Low nutrient retention
Low plant available water
Volcanic ash soils High P fixation
Constraints of ‘problem soils’

11. Problem Soils Constraints Simple Indicators
Acid sulfate soils Acidity
Heavy metal toxicities
pH (oxidised)
EC
Peat soils Acidity
Multiple nutrient deficiencies
High P fixation
Waterlogging
pH
Organic C
Extr P, Extr K
Sandy soils Acidity (high risk of acidification)
Low nutrient retention
Low plant available water
Compaction
Texture
pH
Organic C
Extr P, Extr K
Skeletal soils Low nutrient retention
Low plant available water
Susceptibility to erosion
Texture (gravel/rock)
pH
Organic C
Contaminated and disturbed
soils
Compaction
Hard-setting
Heavy metal toxicities
Land use
Texture
Coral sands Alkalinity?/sodicity?/salinity?
Low nutrient retention
Low plant available water
Texture
pH
EC
Organic C
Extr P, Extr K
Volcanic ash soils High P fixation Air dry moisture
Organic C
Extr P, Extr K

12. What about interpretive guidelines?
Are there other reference sources?

13. • Select a suite of simple soil tests that can be used to infer
soil constraints/ soil fertility of soils of the Pacific region.
• Use ASPAC ILPP as the reference for QA/QC performance.
• Standardise SOPs for the soil tests allowing some flexibility
of procedures /processes provided QA-certified results are
produced.
• Commence harmonisation of generalised interpretive
guidelines.
Suggested future actions:

14. Thanks for your attention