A review of Centre Pivot and
Lateral Move installations in
the Australian Cotton Industry
P Smith, J Foley, S Priest, S Bray, J Montgomery,
D Wigginton, J Schultz, R Van Niekerk
Review of CPLM installations in the Aust cotton industry – P Smith – IAL conference 2014
Introduction
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Australian cotton growers aim to maximise profitability per ML
2001 – review of CPLM in the cotton industry (Foley & Raine)
Since then CPLM uptake increased
Australian Government water reforms and funding programs
stimulated investment
Healthy Headwaters (Qld) funded repeat study in QMDB in
2011
CRDC funded same in 2012-13 for NSW cotton regions
Surveys combined to examine changes in design, operation
and management since 2001
Reporting some results today – full report to be published
Survey design and methodology
 Format of survey was based on 2001
 Designed as face-to-face interview, conducted on-farm
 58 selected cotton & grains irrigators interviewed from
Southern Qld to Central/Southern NSW
 Total 127 CPLM systems irrigating 13,969 ha
 42% of area CP, 58% LM
Survey format
 Questions grouped under headings:
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CPLM dimensions and configuration
pump and water supply
operation management and problems
sprinkler packages
tyres and wheels
farming system
crop water requirements
application strategies
system performance and productivity
runoff management
agronomic considerations
maintenance
purchase decision making
Results and discussion
Number and area of CPLM systems
 2011-12 66% are centre pivots compared to 76% in 2001
 proportion of area covered by centre pivots has declined by
roughly the same percentage
 average area under individual systems has reduced for both
centre pivots and lateral moves
Centre
Pivot
Number of
systems
Lateral
Move
57 (76%)
18 (24%)
Total Area (ha)
2915 (55%)
2385 (45%)
Mean Area (ha)
~70
~165
2001
Centre
Pivot
Number of
systems
Lateral
Move
121 (66%)
63 (34%)
Total Area (ha)
5901 (42%)
8068 (58%)
Mean Area (ha)
51
139
2011-12
Results and discussion
Yield and Water applied
 Water applied by CPLMIWUI
approx
30% less than furrow irrigation
Qld & NSW
 Yields similar
4.5
4
3.5
b or t per ML
3
2.5
2
1.5
1
0.5
0
Corn
Cotton
Sorghum
CPLM
Soybeans
Furrow
Irrigation Water Use Index (IWUI) 2011-12
Wheat
Results and discussion
Adoption drivers
 Main factors 2011-12 labour saving (74%), water saving (62%)
 Compared to the 2001, labour saving replaced water saving as
main driver
 Automation declined a lot: 58% 2001, 24% 2011-12
Results and discussion
Labour requirement
 2011-12:
– CP 47% thought labour less than ¼ of furrow
– LM 56% thought labour ¼ to ½ of furrow
 2001:
– CP 69% thought labour less than ¼ of furrow
– LM 53% thought labour ¼ to ½ of furrow
 2011-12: 59% considered higher skill required for CPLM
Results and discussion
System capacity
 System capacity is important for CPLM design – affects ability to
meet crop water requirements
 Irrigators were asked for the System Capacity of their CPLM
 Check: also calculated from pump flow rate and area irrigated
(provided by irrigators)
Results and discussion
 Design system capacity range 4–32 mm/day
 78% CP operators within 1 mm/day of calculated value
 46% LM operators more than 2 mm/day from calculated value –
probably due to variable area
Difference between stated and calculated Design system capacity
(Fig. A: CP, Fig. B: LM)
Results and discussion
System capacity
 Managed system capacity allows for machine downtime and
application losses
 Better indicator than Design system capacity
Results and discussion
 20% of CPLM more than 110% of peak ET (18% 2001)
 25% between 90% and 110% of peak ET (36% 2001)
 55% below 90% of peak ET
Designed system capacities (left) and Managed system capacities (right)
expressed as % of average Peak January ET
Results and discussion
System capacity
 59% of Design system capacities more than 110% of peak ET
(26% 2001)
– irrigators are increasingly understanding the importance of
adequate system capacity for meeting crop water needs
 However, there are now a greater proportion (55%) with
Managed system capacity that cannot meet peak water
demand (46% 2001) – concerning!
Results and discussion
Pressure and costs
 Higher running costs of CPLM considered a
disadvantage
 Should have pressure no higher than necessary
 Most systems have pressure regulators 15 psi or
less
 Commonly recommendation: supply point pressure
max 15 psi above regulators ie. Max supply point
30 psi
Results and discussion
 52% operating above 30 psi – 2001 59% – room for more
improvement
 None operating above 50 psi – 13% in 2001
Results and discussion
Pressure and costs
 Supply point pressure average 19 psi >regulator, range 0–40 psi
 21% operating at >30 psi pressure difference
 79% have potential to save energy costs
55
50
45
Pressure (psi)
40
35
30
25
20
15
10
5
0
Regulator pressure
Supply point pressure
Results and discussion
 Pressure regulators require min 5 psi above rated pressure
to operate properly – 4 systems not operating properly
 4 systems 40 psi above regulator pressure
55
50
45
Pressure (psi)
40
35
30
25
20
15
10
5
0
Regulator pressure
Supply point pressure
Results and discussion
Emitter Systems
 Emitter systems changed a lot between 2001 and
2011-12
– LEPA systems reduced 48% to 19%
– moving plate sprinklers increased 4% to 54%
 May be due to:
– slight differences in study participants – more
grain in 2011-12
– previous concerns about sprinklers on cotton not
eventuating (pollination effects, lint quality)
 Change consistent with 2001 report –
recommended performance be improved by
converting from static to moving plate
 Pressure regulators used more widely – 95% v.
58% in 2001
Results and discussion
Power Supply and Control Systems
 Proportion of diesel powered machines increased – 79% v 65%
in 2001
 Remaining 21% used mains power – all CP
 90% of machines surveyed were electric drives, 10% hydraulic
 CP: 53% electric drive powered by diesel generator, 42%
electric drive powered from mains, 5% hydraulic drive powered
by diesel motor
 LM: 71% electric drive powered by diesel generator, 29%
hydraulic drive powered by diesel motor
 Automatic control use increased – 40% v 10% in 2001
– Still low considering potential reduction in labour and
increased flexibility
Results and discussion
Wheel Rutting and Bogging
 64% experienced problems with wheel ruts or bogging – 79%
in 2001
 Still a prevalent issue – but mostly minor problems overcome
within first few seasons
 59% of respondents have or will modify their irrigation strategy
or sprinkler set up to help overcome this – most used
‘boombacks’ and half-throw sprinklers around the towers
 Many irrigators commented on need
to check tyre pressures and use of
different tyre configurations to
alleviate bogging
Results and discussion
Scheduling
 Capacitance probes are the tool most commonly used
 2001: generally used one scheduling tool
 2011-12: used combination of tools – both for furrow and CPLM
 CPLM apply less water more often – so operators more
conscious of water use under these
Results and discussion
 Depth per CPLM irrigation range 5–50 mm, median 24 mm
– 52% applied 15–30 mm (33% in 2001)
– 11% fewer growers applied 15 mm or less
– 7% fewer applied more than 45 mm
Depth applied per
pass (Fig. A 2011-12,
Fig. B 2001)
Results and discussion
Fertiliser usage
Fig. A: Change in total seasonal fertiliser
use with CPLM fertigation (2011-12)
Fig. B: Change in pre-season fertiliser
use with CPLM fertigation (2011-12)
Results and discussion
Capital cost of CPLM systems
 Range $610 to $6,000 per hectare, median $2,570 per hectare
(lowest cost included second-hand equipment)
 2001: $1,250 to 2,500 per hectare
 70% between $1500 and
$3500 per hectare
– Large range due to
individual site requirements
– cost of machine, install
machine, pumps, earthworks,
electrical works, system
capacity, currency exchange
rates
Results and discussion
Capital cost of CPLM systems
 Generally, costs decrease as irrigated area increases
 Stronger for LM than for CP
 CP: cost for irrigating same area varies by multiple of six
 Engage an independent expert to evaluate designs and
provide advice!
Results and discussion
System Performance
 IWUI – discussed earlier
 93% of irrigators surveyed had flow
meters or pressure gauges for system
control
 79% used pressure points as an
indicator of problems
 38% use flow meters to monitor changes or problems in
delivery
 62% visually assessed emitters
 Only 25% had measured uniformity – range 50% to 100%
(90% is benchmark)
Thank you!