A presentation on the results of experiments to assess the effectiveness deep application of organic matter and lime to ameliorate sub-soil acidity. Given by Hoang Han Nguyen to a joint meeting of the Riverina and NSW branches of Soil Science Australia at Wagga Wagga on 2 May 2019

1. Amelioration of Subsurface Soil Acidity
Using Organic Matter and Lime
Hoang Han Nguyen
Supervisors: Dr. Sergio Moroni, Dr. Jason Condon,
Dr. Alek Zander and Dr. Guangdi Li
Charles Sturt
University
Riverina & NSW Joint Branch Workshop
Wagga Wagga, May 2019
hnguyen@csu.edu.au

2. Background
Lime Organic matter
Surface soil acidity
Subsurface soil acidity
Lime + Organic matter
Increase soil pH where they
incorporated
Supper slow
Long time
Possibly
Short time
Increase effectiveness?

3. Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
Soil pH profile after 31 days incorporation with lime or fine
ground lucerne pellets (LP) under controlled conditions
Control
None lime LP lime LP lime LP lime LP lime LP lime LP Lime LP
1st
(0-10)
2nd
(10-20)
3rd
(20-30)
4th
(30-40)
4.54.9 4.4 4.9 4.4 4.9
6.2
4.4 4.4 4.6 4.4 4.6 4.4 4.6 4.4
4.2 4.9 4.6 6.0 4.7 6.0
5.5
5.4 5.8
4.2 4.2 4.4 4.2 4.5 4.7 5.4
4.2 5.4 5.7 4.2 4.8 5.4
4.7
4.2 4.2 4.5 5.4 5.5 4.2
5.1 5.2 4.6 4.6
5.7
Soil layer
(cm)
5.2 5.5
1st
, 2nd
, &
3rd
layers
4.6 5.2 5.1 4.6 4.6 4.6 4.6 5.1 5.5
1st
layer 2nd
layer 3rd
layer
1st
& 2nd
layers
1st
& 3rd
layers
2nd
& 3rd
layers
(Moroni et. al., 2018)
Background

4. Research questions
 Can surface incorporation of organic matter increase
subsurface soil pH?
 Does surface incorporation of organic matter in
combination with lime improve the effectiveness of
the amelioration of subsurface soil acidity?

5.  Glasshouse experiment: test the effects of organic
matter (lucerne pellets) sizes in combination with or
without lime on subsurface soil pH and plant growth
 Field experiment: study the effects of surface
incorporation of lucerne pellets in combination with or
without lime on subsurface soil pH and plant growth under
field conditions
Experiments

6. Field
soil layers
0- 10cm
10- 20cm
20- 30cm
30- 40cm
LP2+LLP1+L LP3+L LP4+LLP2LP1 LP3 LP4LimeNil
10cm
10cm
10cm
17cm
50cm
5cm
5cm
White
plastic
bead
Cap end
Glasshouse experiment
LP1
~2cm
LP2
~1cm
LP3
~0.5cm
LP4
0.1-0.2cm
Lucerne pellets (LP) sizes

7. Glasshouse experiment
• Wheat cv. Dart, acid
soil resistant cultivar,
sown
• Watered by weight at
100% field capacity
• Harvested 14, 21, 28
and 35 days after
sowing

8. Soil pH profile after 14 days incorporation
LP1
~2cm
LP2
~1cm
LP3
~0.5cm
LP4
0.1-0.2cm
Lucerne pellets
(LP) sizes
Key results of glasshouse experiment
4 5 6 7
0
10
20
30
40
pHCa
Soildepth(cm)
***
***
***
***
***
***
***
**
***
LP1
LP2
LP3
LP4
Lime
Nil

9. Key results of glasshouse experiment
14 days 35 days
4 5 6 7
0
10
20
30
40
pHCa
Soildepth(cm)
***
***
***
***
***
***
***
**
***
LP1
LP2
LP3
LP4
Lime
Nil
pH in LP treatments
decreased after 35 days
4 5 6 7
0
10
20
30
40
pHCa
Soildepth(cm)
LP1
LP2
LP3
LP4
Lime
Nil
***
***
**
***
***
ns
ns
**
***

10. Surface incorporation
of lucerne pellets in
combination with lime
increases
effectiveness of the
amelioration
Key results of glasshouse experiment
4 5 6 7
0
10
20
30
40
pHCa
Soildepth(cm)
*
ns
ns
ns
ns
ns
*
**
**
+ Lime
- Lime
How incorporation of LP in combination with lime?

11. LP4 LP3 LP2 LP1 Lime Nil
Key results of glasshouse experiment
Incorporation of
ground lucerne
pellets (LP4)
affected plant
growth negatively

12. gplant-1
Key results of glasshouse experiment
Shoot dry weight
LSD = 0.008
0.00
0.01
0.02
0.03
0.04
0.05
LP4 LP3 LP2 LP1 Lime Nil

13. gplant-1
Key results glasshouse experiment
Root dry weight
LSD = 0.001
0.000
0.005
0.010
0.015
0.020
LP4 LP3 LP2 LP1 Lime Nil

14. Field Experiment
 2 genotypes: Gregory
and Lancer, acid soil
resistant and sensitive
cultivars, respectively
 The amendments incorporated into ~5cm of the soil profile
 4 treatments: nil, lime (L)
(2.5 t/ha), lucerne pellets (15
t/ha) (LP) and lucerne
pellets in combination with
lime (LP+L)
Each replicate included 2
genotypes and 4 treatments
Rep 1 Rep 2
Rep 3 Rep 4
10m
15m

15. Field Experiment
Incorporation of the amendments into ~5cm of the soil profile
Before
incorporation
After
incorporation
1. Broke ~5cm
surface layer
2. Run through by
rotary hoe
3. Manually applied
the amendments
4. Incorporated by
rotary hoe

16. -10
0
10
20
30
40
50
0
10
20
30
40
50
60
Temperature(oC)
Rainfall(mm)
Year 2018
Rainfall Max T Min T
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Incorporation of
the amendments
Soil samplings Sowing
Weather conditions
Data from Cootamundra airport (34o63’S, 148o49’E)
station, site number 073142, approximately 20km away
from the experiment location (http://www.bom.gov.au/)
Total 2018: 417mm
Total growing
season: 260mm
3 months after
incorporation:
85mm
6 months after
incorporation:
164mm
8 months after
incorporation:
318mm

17. 3 months after incorporation
Key results of field experiment
pH profile at before and 3 months after incorporation
Before incorporation

18. A mini-plot, 2.5m2
within each plot was
irrigated equivalent to
70mm of rainfall at
booting stage (5 months
after incorporation)
Irrigation the field experiment

19. pH profile at 6 months after incorporation
IrrigatedNon-irrigated
Key results of field experiment

20. pH profile at 8 months after incorporation (at harvest)
IrrigatedNon-irrigated
Key results of field experiment

21. pH profile at 12 months after incorporation (second season)
IrrigatedNon-irrigated
Key results of field experiment

22. Grain yield of the two cultivars
Key results of field experiment
0.0
0.5
1.0
1.5
2.0
2.5
Lancer Gregory Lancer Gregory
Non-irrigation Irrigation
Grianyield(tha-1)
Nil Lime LP LP+L

23. Conclusions
 Surface incorporation of organic matter increased
subsurface soil pH upon water infiltration
 The incorporation of either LP or lime did not significantly
improve grain yield in the first year of incorporation
 However, subsurface soil pH did not increase under field
conditions due to insufficient rainfall to infiltrate into
subsurface soil layer
 The incorporation of organic matter in combination with lime
increased the effectiveness of the amelioration of
subsurface soil acidity

24. Acknowledgement
GRDC for funding DAN00206 project
Richard Lowrie and Adam Lowrie (DPI NSW technical
staff) for assistance in the field work
Grace Kaveney, Jordan Bathgate, Patrick Hawkins
and Matthew Champness for help in soil sampling
The Ministry of Agriculture and Rural Development,
Vietnam for the PhD scholarship

25. THANK YOU