ASPAC | Pacific network of soil laboratories: 1st meeting. Brisbane, Australia, 17 - 18 October 2019. Presenters: De Hayr, Suvannang, Moody

1. Items 16 & 17
What do soil analyses tell us?
Rob De Hayr (ASPAC)
Nopmanee Suvannang (GLOSOLAN)
Phil Moody (University of Queensland)

2. Do you remember your lab analysing (0-15 cm) samples
‘KI’ and ‘LB’ in the SEALNET Inter-Laboratory Proficiency
Program?
LBKI

3. Method KI LB
pH1:2.5 water 5.4 7.8
Walkley-Black org C
(%)
0.4 2.7
Total org C (%) 0.4 3.2
Exchangeable K
(mg/kg)
16 401
Bray 1-P (mg/kg) 4 8.9
Bray 2-P (mg/kg) 3 68.7
Olsen-P (mg/kg) 2.3 10.5
These are the results (median)

4. Discussion of what general conclusions each lab could make about the results

5. So what can we make of the results?
(What can we tell our clients?)
KI LB
Property Implications Property Implications
Moderately acidic Liming required for
acid-sensitive crops
Slightly alkaline Nil
Low organic carbon Retain crop residues
Add
compost/manure
High organic carbon Nil
Low potassium Apply low rates of
potash frequently
and monitor soil K
over time
Adequate potassium Replace potash
removed in
harvested product
Low phosphorus Apply phosphorus at
crop specific rate
and monitor soil P
over time
Adequate
phosphorus for
most crops
Adequate
phosphorus-
monitor soil P over
time

6. Discussion of what management strategies could be inferred from the additional information

7. Other information
KI LB
Landscape position River flat Hillslope
Colour Brown Black
CEC (cmol/kg) 2.7 43
Clay (%) Silt (%) 9, 29 53, 20
Land use Rice Upland
rice/sugarcane
What more advice could we provide with some
extra information?

8. Discussion of what other management strategies could be inferred from the data

9. KI LB
Property Implications Property Implications
River flat Flooding risk,
Denitrification risk
Hillslope Erosion risk,
Denitrification risk if
soil is saturated,
Volatilisation risk
from surface applied
urea
Low CEC Apply fertiliser often
at low rates
High CEC Nil
Low clay, high silt Risk of compaction,
Hard-setting
High clay May be difficult to
cultivate,
Risk of compaction
if tilled when wet
So what can we make of the results?
(What can we tell our clients?)

10. In summary
• Much information can be obtained from a few
simple soil analyses- they are not just numbers!
• When possible, provide your client with
interpretation of the requested analyses
- your lab is not just a factory producing numbers,
but a professional scientific institution!

11. Thanks for your attention