A presentation on the effect of poultry litter on nitrogen mineralisation and soil health when applied to cotton soils in the Riverina, by Dr Rakesh Awale, Deakin University, Griffith, to Soil Science Australia's Riverina branch workshop on "Parna and Cotton Soils" held at Yanco on 29 April 2021.

1. Nitrogen Mineralisation and Health of
Poultry Litter Amended and Non-Amended Soils
in Cotton Cropping Systems of Southern NSW
Rakesh Awale, Jackie Webb, & Wendy Quayle

2. Rationale
➢ Cotton is a significant crop in the Riverina region of southern NSW.
➢ Nitrogen supplied, mainly from chemical fertilisers, based on crop
yield potential.
➢ Poultry litter amended in combination with N-fertilisers – with a view
to enhance soil condition and health.
➢ N-supply from poultry litter amendment often overlooked.
Objectives
1. Evaluate N status and mineralisation potential of poultry litter
amended and non-amended soils in cotton systems of the Riverina.
2. Identify indicators of & assess soil health under these cotton systems.

3. Study Location & Sites
Murrumbidgee
River
Coleambally
Carrathool
Whitton
Griffith
Benerembah
Distribution of Cotton Cropping and Native Sites across Southern NSW
Riverina Region
To Canberra
N
Picture sources: Wikipedia & Google Maps
▪ 10 farms x 3 reps
❑ Native (10)
❑ Conventional (7)
❑ Poultry litter (8)
▪ Litter history
❑ 2.5 to 16 t/ha
❑ 3-17 years
▪ Cropping systems
❑ Cotton-cereal-fallow
▪ Soils (0-15 cm)
❑ Clay loams
❑ Total 81 samples

4. Selected Soil Characteristics
Management
pH
(water)
EC CEC Ca:Mg ESP
Total
Org C
Total
N
C:N
ds/m Cmol/kg ratio % % % ratio
Native
(n=27)
6.92b 0.11b 17.1c 2.22a 3.64a 1.42a 0.11a 13.0a
Conventional
(n=21)
7.72a 0.17a 27.2a 1.38b 4.54a 0.87c 0.08b 10.7b
Litter
(n=24)
7.26b 0.20a 23.1b 1.61b 3.85a 1.15b 0.10a 11.0b
Means with same letters are not different by Tukey test at α=0.10

5. Obj-1: Nitrogen Mineralisation & Availability
[Soil Incubation @ 60% WHC and 25°C for 4-weeks]
b
ab
a
b
a
ab
ab
a
b
-20
0
20
40
60
80
Native Conventional Litter
NO
3
-N
(mg
kg
-1
)
Day0 Day28 Δ (Day28 - Day0)
c
b
a
a
b b
a
b b
-30
-20
-10
0
10
20
30
40
Native Conventional Litter
NH
4
-N
(mg
kg
-1
)
Coloured bars ± std. err with same letters among managements
are not different by Tukey test at α=0.10

6. c
b
a
b
a
ab
a a
b
-40
-20
0
20
40
60
80
Native Conventional Litter
(NH
4
+NO
3
)-N
(mg
kg
-1
)
Day0
Day28
Δ (Day28 - Day0)
Net N-Mineralisation & Availability
[Soil Incubation @ 60% WHC and 25°C for 4-weeks]
Coloured bars ± std. err with same letters among managements
are not different by Tukey test at α=0.10

7. Deakin University CRICOS Provider Code: 00113B
461a
316b
299b
SE
*
*
*
*
*
*
0
50
100
150
200
250
300
350
400
450
500
550
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
Cumulative
CO
2
-C
(mg
kg
-1
) Native
Conventional
Litter
SE
*
*
*
*
* *
0
10
20
30
40
50
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
Daily
CO
2
-C
(mg
kg
-1
d
-1
)
Days of Incubation
Native
Conventional
Litter
Carbon Mineralisation (Microbial Activity)
[Soil Incubation @ 60% WHC and 25°C for 4-weeks]

8. Microbial Biomass & Labile C Availability
Management
Microbial
biomass N
Microbial
biomass C
KMnO4 (0.2 M)
oxidisable C
K2SO4 (0.5 M)
extractable C
------------------------------mg kg-1-----------------------------
Native
(n=27)
70b 320a 454b 74.3a
Conventional
(n=21)
83b 200b 394b 48.6b
Litter
(n=24)
118a 243b 522a 67.4a
Means with same letters within a column are not different by Tukey test at α=0.10
*Microbial biomass analysed using chloroform-fumigation-extraction method

9. Deakin University CRICOS Provider Code: 00113B
y = 0.001x2 - 0.51x + 24.6
R² = 0.43; P<0.05
-60
-40
-20
0
20
40
60
0 30 60 90 120 150 180 210
ΔNH
4
-N
(Day28
-
Day0)
(mg
kg
-1
)
Microbial Biomass N (mg kg-1)
Native
Conventional
Litter
Relationship of NH4-N mineralisation with microbial biomass N

10. Deakin University CRICOS Provider Code: 00113B
Conclusions & Implications
➢ Poultry litter amendments build up soil N status over
conventional soils.
➢ Litter amendments have potential to release more available N
than conventional soils (upon drying and sieving).
➢ Upon rewetting, soil available N (mainly NH4-N) can be
immobilised into microbial biomass and more so with litter
amendments.
➢ The fate of microbially immobilised N on subsequent soil N
availability and cycling deserves further investigation.

11. Deakin University CRICOS Provider Code: 00113B
Acknowledgements
➢ Australian Government Department of Agriculture, Water and
Environment, National Landcare Programme Smart Farms Project
(Funding: Unlocking the true value of organic soil amendments)
➢ Cotton Research and Development Corporation (Funding: Optimising
the management of manures in southern NSW cotton production II)
➢ Irrigation Research and Extension Committee (Project Partner)
➢ Cotton Info (Extension)
➢ Collaborating Cotton Growers (Survey & Soil Sampling)

12. Deakin University CRICOS Provider Code: 00113B
Questions & Comments
Rakesh Awale
Post Doctoral Research Fellow
Centre for Regional and Rural Futures (CERRF)
Deakin University
rakesh.awale@deakin.edu.au