Do the challenges of a strip disc system pay off – a grower’s perspective

Take home messages

• Strip disc systems can retain more plant available water (PAW).
• Mice and insects love the extra soil cover.
• Herbicide options change with a strip disc system.

Background

Konzag Grains farms 2500ha at Mallala in the Lower North of South Australia in a 395mm rainfall zone, growing wheat, durum, barley, lentils, faba beans, chickpeas, canola and oaten hay. Soil types range from clay to grey Mallee loam to sand.

Key question 1- what drove us to switch to this system?

There were several factors that drove us to change systems. We previously ran a ConservaPak seeder on 12” spacings.

• I felt on 12” spacings we were seeing intra-row crop competition which was producing lower biomass levels and when neighbours were cutting droughted crops for hay, we didn’t have enough biomass to make a hay crop.
• We had a demo of the JD 1890 (7.5” spacings) in 2013 which we sowed run for run with our ConservaPak. We found 40% more heads in the rows where we planted with the disc seeder (Table 1). Yield difference was much less impressive with the crop sown with the JD single disc, 7.5” row spacing yielding 1-2% higher than the crop sown with the ConservaPak, 12” row spacing.
• I wanted to narrow up our row spacings to increase crop competition with weeds.
• I purchased the stripper front after doing a trial with a neighbour’s stripper front in comparison with our draper front and found 48mm more PAW in the stripper straw compared with the draper straw.

Table 1. Seeder and row spacing comparison- 2013

Key question 2 - what are the advantages of implementing a strip disc system?

A big advantage of moving to the strip disc system is being able to have total stubble retention which gives complete soil cover while being able to plant crops on narrower row spacings.

Moving from 12” row spacings back to 7.5” row spacings has dramatically increased competition between the crop and the weeds, thereby reducing the pressure placed on herbicides.

Hair-pinning of stubble with a single disc seeder can be an issue, however using a stripper front lessens the amount of smaller straw fractions or ‘cocky chaff’ which is the thing that causes most of the hair-pinning issues.

Depending on the season, using a stripper front can increase harvester capacity and reduce fuel consumption during harvest, as there is less material being processed by the harvester.

There is anecdotal evidence that harvesting with a stripper front can reduce snail numbers because the stripper front rotor either smashes the snails on contact or flicks them against the crop hood, cracking their shells and causing them to dehydrate and die. We do not rely solely on the stripper front as a snail control method but rather, implement a strategic baiting and cabling system to assist with snail management.

Better soil cover in a stripped cereal stubble reduces wind speed over the soil surface which helps to reduce the evaporation of stored soil moisture. Additionally, having full stubble cover reduces wind and water erosion and the impact of raindrops on the soil surface which can cause surface sealing.

Faster sowing speeds with a disc seeder can result in timelier crop establishment when conditions are right.

Flat paddocks with a disc seeder enable easier harvesting of low pulse crops like lentils without having to prickle chain paddocks after seeding.

While we have been retaining stubbles on our farm since the mid-1980s, the stripper front system gave us an opportunity to harvest straw in 2019, following the grain harvest. Income was down due to frost and the dry season, so we took the opportunity to bale the straw and make some money with high straw prices. This was done with reluctance given our focus on stubble retention but nevertheless performed with the knowledge of our history of stubble retention and minimum/zero tillage over a large number of years and and recognising that it will not become a regular practice.

Key question 3 - what were the challenges of switching to this system and are there disadvantages?

Switching to the disc seeder initially felt like I had to learn to farm again.

You cannot just go planting when you want, as the straw needs to be dry for the disc to cut through it effectively and reduce hair-pinning. Moving from 12” spacing to the single disc system caused some concern with the high furrow ridges of the ConservaPak and the possibility of them affecting sowing depth in the first year of the disc. Initially we did have variation of seeding depth and it probably did affect the crop vigour in some rows.

Pre-emergent herbicide options are reduced. Herbicides with high solubility e.g. Boxer Gold® and Sakura®, work better in high stubble systems. We use virtually no Trifluralin® anymore but have not missed its volatility.

Weed spectrums have changed slightly with weeds like fumitory making a comeback in the absence of Trifluralin®. Therefore, you need to be on top of your game with crop monitoring as changes occur.

The disc seeder does not ‘scalp’ herbicides out of the row like a knife point, so herbicide damage can be an issue, particularly in pulses, if you get a big rainfall event post sowing. The disc can also push straw and chaff containing herbicide into the sowing slot and affect germination.

Kondinin Group researcher, Ben White has found that harvesting with stripper fronts resulted in grain losses of at least 1% during trials they have conducted. However, in my experience, we have been unable to detect losses from the stripper front in cereal crops in normal conditions. Modern stripper fronts have variable rotor speeds that can be adjusted to suit varying conditions. In certain conditions, we can harvest the wheat and leave the chaff on the stalk. At this stage we have not had success harvesting lentils with the stripper front although we are aware of people that have done so.

Long stripper straw makes an ideal home for insect and vertebrate pests. Careful management of crops for insect pests is vital for the success of the strip disc system and needs due consideration in pre-season planning. Mice have been a big problem during the implementation of our system and require almost constant attention pre-sowing and during germination. The mice have learned that the long straw offers protection from overhead predators. We have seen on many occasions, near perfect crop establishment on wheel tracks where the straw is rolled down, only to discover mice have cleaned up the seed in the long straw. To address this issue, we have mounted a mouse bait spreader on the back of the seeder cart to apply bait at sowing, with varying degrees of success.

Conclusion

A strip disc system can have both financial and farming system benefits, through timely planting of the crop, improved crop competition with weeds, less wear and tear on machinery and reduced fuel use on the harvester. However, the strip disc system does come with some challenges; with reduced herbicide options, potential for increased herbicide damage of sensitive crops and possible higher pest numbers.

Acknowledgements

I would like to acknowledge the agronomy advice of Bill Long and Stefan Schmidt of Ag Consulting Co, my family, and staff at Konzag Grains.

Useful resources

GRDC Grains Research Update Paper: Stripper fronts and disc seeding

References

Harvesting Special Research Report, Strip show provides plenty of food for thought, Farming Ahead March 2017

Contact details

Richard Konzag
PO Box 117 Mallala SA 5502
0417 830 406
richard.konzag@gmail.com
@RichardKonzag