Control Traffic Farming in the low rainfall zone
of Victoria
Pearl D1 , Cann M2 and Peries3
1,2
Department of Economic Development, Jobs, Transport and Resources (DEDJTR), Swan Hill
3
Department of Economic Development, Jobs, Transport and Resources (DEDJTR), Swan Hill
Peer review: David Rees Research Scientist, DEDJTR, Parkville
Background
Throughout history many farm practices have emphasised productivity at the expense
of natural resource condition. These farming practices have impacted on the sub soils
of these systems, creating an environment that is impoverished, preventing root access
and proliferation, carbon capture and access to deeper soil moisture.
In the age of large and heavy machinery on farms, the use of this machinery on paddocks in random trafficking
over the soil, can result in chronic soil compaction affecting crop growth, increased nutrient run-off and soil
erosion, reduced carbon cycling and soil biological function, and low water and nutrient use efficiency.
Why was the project done?
While Control Traffic Farming (CTF) is well established in Qld and NSW, uptake across Victoria is poor, particularly
in the medium to low rainfall zones. CTF, a system by which all heavy farming vehicles continually travel on the
same wheel line, offers the opportunity for reduced compaction, improved carbon capture and water infiltration
and an increase in production.
This project was established to assist the Growers of the Low to Medium rainfall zones in improving their
knowledge of the opportunities that CTF brings by giving them access to demonstration sites and data from within
their local region.
With the assistance of local CTF farmers, paired paddocks sites were established at 8 locations across western
Victoria. Paired paddocks are where two paddocks adjacent to each other but being managed under different
practices are sampled and monitored. In this case the differences in the paddocks were that one was under a
CTF direct drill cropping system and the other is district practice. The sites in the Victorian Mallee where at
Mittyack, Nowie and Roseberry.
Key messages
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rainfall at all sites in 2014 and 2015 was below the Mean for the sites
In 93 % of cases, Non-trafficked CTF areas had greater biomass than trafficked CTF areas.
In 100% of cases, Non-trafficked CTF areas had greater yields than trafficked CTF areas.
In 73 % of cases, including farmer yield history data, when the paired paddocks were growing the same
type of crop in the same year, the CTF paddock out yielded the Non CTF Paddock.
While bulk density figures showed no significant differences, except under CTF wheel tracks,
penetrometer readings indicated that roots were less restricted in the soils in the CTF paddocks, other
than on the wheel tracks.
Results and discussion
The bases on which CTF is perceived to improve cropping systems is through improved production and more
efficient running of machinery through energy savings and access to paddocks. The project explored the
improved production and examined both plant performance and soil properties. It is suggested that CTF soils
have improved soil structure which increases water capture and allow plant roots greater opportunities to
extract both moisture and nutrients.
This paper will focus on some of the data collected from the low rainfall sites. The overall project had eight paired
paddocks sites of CTF and Non CTF which allowed us to take a variety of soil and crop measurements, so that
each season could be compared. The three paired paddocks presented in this article were adjacent to one another.
However, unless both paddocks were sown to the same crop type, it was not possible to compare the crop
performance of the two paddocks in the same year. Over the two years, in four instances, the same type of crop
was grown in the paired paddocks.
1 At these locations the CTF crop had greater biomass at spring and at harvest. Yield also followed this pattern. In
eight out of nine cases, comparing crop performances on Wheeled and un-Wheeled areas, the un-Wheeled area
produced higher biomass, as can be seen in Table 1. Table 2 shows that in all cases, the un-Wheeled CTF areas
out yielded the Wheeled areas in 2014.
Table 1. Spring and Harvest Bio Mass t/ha for CTF, CTF Wheeled areas and Non CTF paired paddocks
Location and treatment
Crop
2014 Harvest
Crop
2015 Spring
2015 Harvest
type
Biomass t/ha
type
Biomass t/ha
Biomass t/ha
Wheat
4.84
Wheat
0.55
2.69
Nowie CTF
Wheat
4.22
Wheat
0.29
1.85
Nowie CTF Wheel area
Wheat
2.35
Barley
0.65
2.75
Nowie Non CTF
Barley
5.92
Field
1.88
2.69
Mittyack CTF
Peas
Barley
6.38
Field
1.02
1.12
Mittyack CTF Wheel
Peas
area
Wheat
4.59
Vetch
2.29
0.99
Mittyack Non CTF
Wheat
4.58
Wheat
3.58
Roseberry CTF
Wheat
2.84
Wheat
2.38
Roseberry CTF Wheel
Vetch
1.11
Wheat
3.11
Roseberry Non CTF
Table 2. Grain yields in t/ha for CTF, CTF Wheeled areas and Non CTF paired paddocks
Location and treatment
Crop type
2014 yield t/ha
Crop type
Nowie CTF
Wheat
1.82
Wheat
Nowie CTF Wheeled
Wheat
1.69
Wheat
Nowie Non CTF
Wheat
0.89
Barley
Mittyack CTF
Barley
1.64
Field Peas
Mittyack CTF Wheeled
Barley
1.60
Field Peas
Mittyack Non CTF
Wheat
1.63
Vetch
Roseberry CTF
Wheat
1.06
Wheat
Roseberry CTF Wheeled
Wheat
1.01
Wheat
Roseberry Non CTF
Vetch
N/A
Wheat
Note - all yields are calculated using hand cuts
2015 Yield t/ha
0.931
0.713
0.777
0.807
0.324
0.189
1.458
0.986
0.493
From the results, we can see that plant growth and yield has improved on the areas which were un-trafficked. It
is suggested that the plant growth and yield increases are a result of an improved soil environment surrounding
plant roots, allowing for better plant root development and improved water infiltration.
4.50 4.25 4.00 3.75 3.50 3.25 3.00 2.75 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0.00 Distance
kPa
Depth
Non CTF
0‐2000
2001‐3000
10 cm
3001‐4000
20 cm
4001‐5000
30 cm 5001‐6000
40 cm
50 cm
6001‐7000
7001 +
Figure 1: Penetrometer readings across 4.5 meters of Non CTF paddock at Nowie
2 kPa
0‐2000
2001‐3000
3001‐4000
4001‐5000
5001‐6000
6001‐7000
7001 +
Figure 2: Penetrometer readings across 4.5 meters of CTF paddock at Nowie
Penetrometer readings were taken at all sites and all paired paddocks showed that the soils had a level of root
resistance due to the lack of soil moisture in the soil profile. It is noted by Whitemore et al (2009) that at 2000 to
2500 kPa, plant root elongation is impeded and in 2011 Whitemore et al notes that “The pressure, as determined
by a penetrometer, at which plant roots become unable to extend into a soil varies by species but is generally in
excess of 3 MPa” (1MPa = 1000kPa). By combining the penetrometer readings for each 10 cm zone and creating
a kPa range we are able to show that at 20 cm to 30 cm, the non-CTF paddocks have higher resistance readings
than the CTF paddocks. As these values in the non-CTF paddock are well above 3000 kPa, root growth is being
restricted. This root restriction would decrease the opportunities for plant roots to extract both moisture and
nutrients. In all CTF paddocks, the wheel traffic zones were clearly identifiable as can be seen in Figures 1 and 2
at the 1-metre mark (5th sampling point), comparing both Nowie paired paddocks.
Table 3 Bulk density samples for Nowie, Mittyack, and Roseberry to a depth of 50cm
Location and treatment
0-10 cm
10-20 cm
20-30 cm
30-40cm
Nowie CTF
1.14
1.52
1.43
1.34
Nowie CTF Wheeled
1.34
1.51
1.54
N/T
Nowie Non CTF
1.25
1.63
1.51
1.44
Mittyack CTF
1.17
1.44
1.43
1.37
Mittyack CTF Wheeled
1.24
1.49
1.37
1.38
Mittyack Non CTF
1.28
1.70
1.62
1.53
Roseberry CTF
1.07
1.46
1.43
1.49
Roseberry CTF Wheeled
1.19
1.49
1.43
1.46
Roseberry Non CTF
1.10
1.54
1.53
1.52
N/T- no sample taken as the soil was too tight for the sampler
40-50 cm
1.29
N/T
N/T
1.27
1.35
1.43
1.52
1.47
1.55
Bulk Density figures indicate the amount of open space in a soil in which plant roots can exchange gas and
capture water. The higher the bulk density the less space the soil has for this exchange to occur. The bulk
density for the three sites all show lower densities for the CTF paddocks compared to the non CTF with the
Mittyack site showing the greatest difference, ranging from 0.11 to 0.26 less than the CTF across the depths.
The CTF Wheeled area is higher compared to the CTF area but the Wheeled area does not always have higher
bulk densities than the non CTF. At Nowie, the Wheeled area is higher than the Non CTF in all except the 10-20
cm depth and the only other location where the CTF Wheeled area has higher bulk densities than the Non CTF is
Roseberry’s 0-10 cm depth.
Conclusion
The Mallee demonstrations in CTF showed varied but positive results to date, but have not necessarily resulted in
significant differences because of sub-optimal rainfall and the difficulty in comparing true paired paddocks over
two growing seasons with the same crop type each year. The observed changes give us confidence to continue
monitoring some sites to further build on already gained knowledge.
References
Whitmore A.P, Whalley W.R. 2009 Physical effects of soil drying on roots and crop growth Journal of
Experimental Botany Vol 60 No 10 pp 2846
Whitmore A.P, Whalley W.R. Bird N.R.A, Watts C. W, Gregory A.S, 2011 Estimating soil strength in the rooting zone
of wheat Plant Soil pp373.
3 Acknowledgements
Thank you to the Department of Agriculture and Water Resources for funding the project through the National
Landcare Program (Innov#074) and to our partners in the controlled traffic farming component of the project,
Victorian no-till Farming Association.
4