2006 Comparison of Disc & Tine Implements
Summary
This trial was designed to highlight some commonly asked questions
involved in the disc versus tine debate. It showed that the disc
machine was more successful than the tine in getting seeds to germinate
and establish, but the depth of sown seed was also important due to the
drying conditions around sowing. Measurements taken up to 35 days
after sowing also demonstrated that seeds sown into moisture with good
seed-soil contact had greater early vigour than those where moisture
was more marginal.
Trial Aims and Design
The grain
growing community in the central west of NSW is divided over whether disc
sowing technology or tine sowing technology is the way of the future for the
various soil types, sowing conditions, farming systems and rotations employed
in the region. Subtle differences exist
between manufacturers of the two types of machinery. The GRDC held a light-hearted debate at the
Dubbo Update in 2007 to highlight the key issues.
This project aimed to quantify
the performance of the two sowing technologies under zero tillage farming
systems. Performance criteria such as establishment percentage, and final yield
were to be assessed.
The aim of the field trial was to demonstrate to
growers the advantages and disadvantages of disc and tine sowing technologies
and their impact on crop establishment and yield.
Back to Top
The site chosen for the trial was at
"Almirica", owned by the Tink family, 25km east of Narromine. Due
to delays in planting the commercial parts of the property (late
break), this trial was not planted until 9 August.
A summary of the main aspects of the trial are as follows:
| Paddock History: |
Wheat in 2005, fallow in 2004
and wheat in 2003 and 2002. Sampling of stubble indicated
moderate-high levels of CR (20-50%) and low-moderate levels of Crr
indicating a high disease pressure. |
| Date Sown: |
9 August 2006 |
| Variety: |
Sunstate at 60kg/ha.
Crown Rot
- 3, Common Root Rot - 6, Stripe Rust - 7, Yellow Leaf Spot - 3,
Root
Lesion Nematode - 7; NSW DPI ratings. |
| Starter Fertiliser: |
100kg/ha MAP. |
| Equipment Used: |
12m NDF precision seeder with
disc and tine delivery assemblies, pulled by a 285hp John Deere
tractor. MAP was placed using the tine, followed by the seed sown
with the disc. For more information, visit www.ndf.com.au. |
| In-Crop Spraying: |
3 September - 75mL/ha Topik, 0.5L/100L Hasten at 70L/ha |
The rainfall received at the site is as follows:
| 1 July |
0.4 |
4 August |
7.0 |
4 September |
2.0 |
The
total amount of rain received from 1 December 2005 to 30 June 2006 was
116mm. Let's use some very broad assumptions, such as all fallow
moisture was stored with 40% efficiency, and the crop converted
available moisture at an efficiency of 15kg/mm. Using the
French-Schultz model and an evapo-transpiration loss of 110mm, we would
expect the crop to fail^. This corresponds to the fact no yield was obtained off the trial area.
|
| 3 July |
0.8 |
6 August |
0.2 |
7 September |
4.0 |
| 10 July |
0.2 |
25 August |
4.0 |
8 September |
0.2 |
| 15-19 July |
26.2 |
26 August |
0.2 |
10 September |
3.0 |
| 23-26 July |
11.6 |
31 August |
3.0 |
19-22 October |
1.2 |
| TOTAL |
39.2mm |
|
14.4mm |
|
10.4mm |
| TOTAL IN-CROP RAIN RECEIVED = 23.6mm |
^ French-Schultz model: (in-crop rain + available fallow moisture - 110) x 15kg/ha/mm ÷ 1,000 = expected yield in t/ha
(24.8 +
155 x 40% - 110) x 15 ÷ 1000 = negative number
Back to Top
Results
Sowing Depth
The results of the depth of sowing were as follows (average readings of all counts in both replicates):
Disc Shallow: 12mm
Tine Shallow: 9mm
Disc Deep: 18mm
Tine Deep: 30mm
These results made interpretation of later results difficult due to the
large difference in the two deep depths. We were surprised at how
difficult it was to get the disc down to a significant depth, and this
highlights one of the limitations of disc machines. Should you
wish to chase moisture for a deeper sowing, disc machines do not give
you the same flexibility as tined machines. It also made
comparisons of emergence data between disc and tine on the "deep"
settings difficult, as there is a 70% difference in starting depth,
which was highly statistically different. The difference in mean
sowing depth between disc and tine at the "shallow" depth was not
significant.
There was a large difference in the number of plants established under
the different regimes. The disc machine
was twice as effective at establishing plants when counted 16 days after sowing
(DAS). Furthermore, the deep planting
lead to slightly higher plant establishment than shallow sowing. Both these trends are also evident when the
method and depth interactions are examined (Figure 1). Rainfall around sowing should have been
adequate (7mm received 5 days prior to sowing and 4mm 16 days after sowing). Overall, the two major
outcomes noticed were:
- The disc
machine was more successful in getting seeds to germinate and grow – perhaps
due to better seed-soil contact
- Deeper sown seeds established more readily than those
on the surface – perhaps greater soil coverage reduced moisture loss to the seed
Figure 1: Plant establishment under different sowing methods
However, the purple bars illustrate that the differences observed 16 DAS
were not evident 35 DAS. Several reasons
may explain these results:
- An
improvement in the plant counts on the tine results was the main reason
for increase in plant populations 35 DAS.
This suggests more plants sown by tine may have germinated on
subsequent rain, whereas the disc resulted in most seeds germinating
directly after sowing. Improved
seed-soil contact may have been the reason this occurred.
- The
measurements showed a high degree of variability. This, coupled with the fact that plant
establishment was very low overall (the target population was 90 plants/m2,
compared to the average 50 plants/m2 counted 35 DAS), mean the
results must be treated with some caution
Back to Top
The height of plants was also measured regularly during the first 5
weeks after planting in order to determine if there were any effects on early
crop vigour. Figure 2 illustrates
these measurements and highlights some interesting results.
The clear trend to be observed is that the deeper sown plants ultimately
showed greater early vigour and growth rate.
It is suggested that this was due to a faster establishment rate, better
early root growth and improved ability to access moisture from further down the
profile. This may not have been so
pronounced had more in crop rainfall been received, but it highlights the
importance of early crop vigour.
There is even a difference between the “shallow”
sowings, with the disc at 12mm showing greater growth rate than the tine at
9mm. All these results highlight the
importance of placing the seed into moisture and obtaining a rapid, early
establishment. At the time of writing,
early crops are being planted in 2007, and these results are being replicated
in the field. Because conditions are
causing rapid moisture loss (unseasonably warm, sunny days with drying winds),
crops sown deeper into moisture are emerging more rapidly. Machines using minimal soil disturbance (e.g.
disc openers) are also seeing better emergence.
In both instances, patchy crops have resulted where seed has not been
put into sufficient moisture.
Figure 2: Plant growth under different sowing methods and depths
Once again, the lack of rain meant that no yield data was obtained from this site.
IMAG will replicate this trial work again in 2007.
Back to Top