This document summarizes a study on the impact of trash management and tillage on soybean productivity in sugarcane farming systems. The study tested different combinations of trash management (full trash retention, partial removal through baling, or burning) and tillage intensity (conventional tillage, strip tillage, or direct drilling). Strip tillage was found to improve soybean establishment and early growth compared to direct drilling, while maintaining comparable yields to conventional tillage. Strip tillage addresses subsoil constraints while maintaining surface cover benefits. The results suggest strip tillage warrants further commercial evaluation as it can facilitate reduced tillage within a controlled traffic system to deliver soil health benefits.

1. Department of Employment, Economic Development and Innovation
The impact of trash management and tillage on
soybean productivity in sugar based farming
systems
Neil Halpin – DEEDI Bundaberg
Dr Mike Bell – QAAFI Kingaroy
William Rehbein and Sherree Short– DEEDI Bundaberg

2. Australian Sugar Industry
• Worth $2 Billion/Yr – (2nd largest export crop behind wheat)
• 350 – 400 000 ha
• 32 – 35 Million tonne of Cane
• 4.5 – 5 Million tonne of Sugar
• 4000 Cane growing Businesses with 6000 growers
• 24 sugar mills
• Employs 40 000 people directly and indirectly
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 2

3. Southern Canelands
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 3

4. Southern Canelands
• Includes the Bundaberg, Childers and Maryborough growing regions
Bundaberg Childers Maryborough
Area of cane (ha) 19 000 13 000 10 000
Productivity 81 84 64
(tCane/ha)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 4

5. The Sugar Yield Decline Joint Venture
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 5

6. A more sustainable sugarcane farming system has 4 key components
Grain legume rotations
Reduced Tillage
Controlled traffic
Trash retention
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 6

7. Why are grain legume rotations important?
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 7

8. 150
130
Cane yield (t/ha)
110
90
Yields average at least 20% greater after
70
grain legumes over whole crop cycle
50
Plant R1 R2 R3
Cane (Ploughout/replant) Grain legume crop (12 M)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 8

9. Grain legumes greatly improved the soil biology (Bundaberg rotation trial)
No. nematodes/200 ml soil
After cane After legume
Lesion 49 14
Reniform 309 23
Stubby root 9 1
Spiral 199 28
TOTAL 566 66
Bacterial feeders 1905 6997
Fungal feeders 1258 1958
TOTAL 3163 8955
Beneficial/Pests 6:1 136:1
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 9

10. Aggressive tillage destroys soil structure and costs time and money
A reduction in tillage offers an opportunity to save money and reduce
impact on soil structure
Tillage Treatment Effects on Inputs
250 25
Fuel (L/ha) Power (kW/ha)
200 20
Hours / ha
150 15
100 10
50 5
0 0
Conventional Tillage Zonal Min Tillage Stool Sprayout
Fuel kW Hours
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 10

11. Why do we need to control traffic?
Cane grown on 1.5m rows.
Harvester on 1.8m centres
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 11

12. Why retain trash?
• Weed suppression
• Water conservation
• Improved soil carbon status
• Improved rainfall capture
Cane trash management effect on soil labile carbon
2.5
2
Labile carbon (mg/kg)
1.5
1
0.5
0
1
Burnt GCTB
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 12

13. Benefits of trash continued
Effect of organic matter retention on nematode supression - RKN
250000
200000
RKN/200mL soil
150000
100000
50000
0
None GCTB
Soil Cover
OM Cane OM Cane and Soy OM Nil
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 13

14. This is all really great stuff! Are producers adopting these practices??
• Some components like legume rotations are well adopted
• Controlled traffic is gradually being accepted
• There has been some reduction in tillage BUT – Dealing with a large
trash blanket and a relatively short time frame between crops is
problematic
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 14

15. How do you handle this amount
of trash and cycle between
cane harvest and legume
planting?
Trash yield relative to cane yield
13.0
12.0
Trash blanket (T/ha)
11.0
Typically there is 7 -12 t/ha of
10.0
cane trash post harvest of the
9.0
final ratoon
8.0
7.0
6.0
40 60 80 100 120 140
Cane Harvested (T/ha)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 15

16. Trash Management option 1: Retain GCTB
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 16

17. 2 passes with Rotary hoe
Then a deep ripping
A final rotary hoe operation will
occur pre-plant to provide a good
seed-bed.
Hardly minimum tillage system!
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 17

18. Trash management option 2: Bale the trash
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 18

19. Baling trash allows for a reduction in tillage
• However aggressive tillage equipment is still utilized
• Exporting nutrients and organic matter out of the farming system
Nutrients in Cane Trash (Relative to cane yield)
120
100
Kg of nutrients / ha
80
60
40
20
0
0 20 40 60 80 100 120 140
Cane yield
Nitrogen Phosphorous Potassium Calcium Magnesium Sulphur
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 19

20. Trash management option 3: Burn trash
Most of the nutrients other
than N are retained yet
complete loss on organic
matter
Allows a reduction in tillage
compared to the full trash
model
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 20

21. How we manage cane trash and tillage will have a large impact on
the farming system
• Remember the New Farming System has Trash retention, reduced
tillage, legume rotations!
• Removal of trash and use of aggressive tillage equipment will
REDUCE the potential soil health benefits that the New Farming
System can deliver
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 21

22. Trash management by tillage trial
• Determine the impact of differing trash and tillage management
techniques on soybean productivity
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 22

23. Trash Management Options
Full Trash Burnt
Some Removed
by
Tillage Options
Full Tillage Zonal – “Strip-Till” Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 23

24. Trash management options have already been explained
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 24

25. Tillage treatments
• Conventional Tillage = 3 rotary hoe operations and 1 deep ripping
• Strip Till = Coulter rip on soybean plant line and 2 passes of fluted
coulter
• Direct Drill = No Tillage
Factorial trial replicated 3 times in plots 5 cane rows wide by 25m length
The trial was fully irrigated via travelling irrigator
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 25

26. Treatment Trash Management Tillage
1 Full Trash – GCTB Conventional Tillage
2 Full Trash - GCTB Strip Till
3 Full Trash - GCTB Direct Drill
4 Baled - Some removed Conventional Tillage
5 Baled - Some removed Strip Till
6 Baled - Some removed Direct Drill
7 Burnt Conventional Tillage
8 Burnt Strip Till
9 Burnt Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 26

27. Strip-till equipment to alleviate sub-soil constraints
yet leave trash on the surface
Cane controlled by “double-knock”
herbicide application technology
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 27

28. Soybean planter
Large coulter to cut through
trash
Double Disc openers
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 28

29. Soybean planter
Vacuum plate seed meter
Twin inclined press-wheels
Innoculant water injected peat
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 29

30. Site planted – 24th November 2009
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 30

31. Trash management had no effect on crop establishment
Trash managment effect on soybean establishment
350,000
300,000
250,000
Plants/ha
200,000
150,000
100,000
50,000
0
1
GCTB Baled Burnt
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 31

32. Tillage had a significant effect on soybean establishment
Tillage effect on soybean establishment
400,000
350,000
300,000
Plants/ha
250,000
200,000
150,000
a a b
100,000
50,000
0
1
Conventional Strip-Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 32

33. Flowering biomass 42 (DAS)
Trash management effect on biomass at flowering
Dry matter production (t/ha)
2
1.5
1
0.5
0
1
GCTB Baled Burnt
Trash management didn’t significantly effect productivity at flowering (p=0.066)
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 33

34. Biomass production at flowering 42 (DAS)
Conventional Strip-Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 34

35. Tillage effect on biomass production 42 (DAS)
Tillage effect on biomass production - flowering
Dry matter production (t/ha)
2.5
2
1.5
1
0.5 a a b
0
1
Conventional Strip-Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 35

36. Trash management effect on maximum biomass – 113 (DAS)
Trash management effect on maximum biomass
Dry matter production (t/ha)
12
10
8
6
4
2
0
1
GCTB Baled Burnt
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 36

37. Tillage effect on maximum biomass production – 113 (DAS)
Tillage effect on maximum biomass production
Dry matter production (t/ha)
12
10
8
6
4
2
0
1
Conventional Strip-Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 37

38. Grain Yield
Cane trash management effect on soybean grain yield
5
4.5
4
Grain yield (t/ha)
3.5
3
2.5
2
1.5
1
0.5
0
1
GCTB Baled effects
n.s. Burnt
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 38

39. Grain Yield
Tillage effect on soybean yield
5
4
Grain (t/ha)
3
2
1
0
Full Tillage Strip Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 39

40. Large effect of tillage on plant height
Tillage effect on soybean height
80
Plant height at harvest (cm)
60
40
a a b
20 Tillage effect on lowest pod height
Lowest pod height at harvest (cm)
0 10
Full Tillage Strip Till Direct Drill 8
6
4 a a b
2
0
Full Tillage Strip Till Direct Drill
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 40

41. Tillage effect on plant height
Direct Drill
Conventional – Strip Tillage
Full - till
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 41

42. Pods set close to the ground are difficult to recover and reduce yield
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 42

43. Strip Tillage system warrants commercial evaluation
• Strip tillage overcame the significant constraints associated with a
reduced tillage system by:
– Improved crop establishment (compared to direct drill)
– Increased early growth (compared to direct drill)
– Comparable crop height and height of lowest pod to
conventional
• Strip Tillage
– Addresses sub-soil constraints
– Maintains surface cover – erosion, soil carbon, weed &
nematode suppression
– Facilitates a reduced and less aggressive tillage regime
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 43

44. Reduced tillage on a controlled traffic platform
• Has the potential to deliver significant
benefits to the Australian sugar industry
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 44

45. Where to from here??
• The site has now been planted to cane with the tillage treatments
maintained.
• This trial has been repeated with peanuts rather than soys
• Commercial evaluation needs to take place
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 45

46. Acknowledge
• Bundaberg Sugar for access to site
• Trial activity was funded by GRDC/SRDC and part of DAQ00129
Improving the integration of legumes in grain and sugarcane farming
system in southern Queensland.
© The State of Queensland, Department of Employment, Economic Development and Innovation, 2011 46