3-step implementation of the ‘strip and disc’ system
June 10, 2019
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with Greg Condon at WeedSmart Week 2018, Narrabri
Having seen the ‘strip and disc’ system working well on South Australian farms several years ago, a number of growers in southern NSW adopted the concept and are constantly making modifications to suit their soils and rotations. The system has been successfully modified to suit their growing region and WeedSmart southern agronomists Greg and Kirrily Condon are convinced that it can be modified to suit other growing regions across Australia.
Step 1 – Disc seeding
Disc seeding helps retain soil moisture at sowing in a no-till farming system and does not generate hard-to-manage clods at the surface like tines often do. The extra moisture enables calendar sowing at the earliest planting date suited to the crop and region.
For best results with single disc seeding it is essential to exert sufficient downward force to achieve even soil penetration in a zero-till system. It is important to use sharp discs and seed firming wheels to help close the furrow.
Likely challenges are associated with potential hairpinning of stubble, inadequate seed-soil contact, and blockages if clumps of residue have been left after harvest. Diligent maintenance of the planter and discs is essential, insect pressure can be greater, especially in canola, and there are fewer pre-emergent herbicide options due to the higher stubble load.
Tines are often preferred for crop safety in low to moderate stubble situations, but are not well-suited to the narrow row spacing that is an integral component of this system for integrated weed management.
Step 2 – Narrow rows
Narrow row spacing increases cereal and canola yields by 1% for even inch reduction in row spacing. Using a 16.5–19 cm (6.5–7.5 inch) disc seeder, growers can achieve increased cereal yields, more even ground cover and any weeds that are present will produce less seed.
When crops are sown at narrow spacing and then harvested high, the standing stubble shades the soil surface; reducing evaporation and cooling the soil. Field measurements taken in February 2017 showed that when the air temperature was 42 degrees C, bare soil temperature was 52 degrees C and under the stripper straw the soil surface temperature was measured as 32 degrees C, a staggering 20 degrees cooler than bare soil in the same paddock.
Using the same established plant number as a wider row configuration, narrow rows force weeds to grow taller and set their seed higher in the canopy, where they are more easily captured at harvest.
Step 3 – Shelbourne stripper front
A rearwards rotating rotor with stripping fingers strips grain from the grain heads. The stripper front threshes 85% of the grain, leaving only a limited amount of chaff (including weed seeds and small grain) to go through the header. The tall stubble provides shading of the soil surface, improving moisture conservation and fallow efficiency.
Stripper fronts only work well in high residue crops. They are best suited for use in cereal crops sown on narrow rows (less than 250 mm spacing), and generally don’t work well in canola or pulse crops.
A stripper front harvesting a cereal crop at a harvest height of 60 cm, uses 50 per cent less fuel than a draper front operating at the conventional height of 20–40 cm. The harvester can harvest 50–70 t/hr because there is far less material to be processed through the machine, which also means there is less wear and tear and lower maintenance costs.
A stripper front can be just as effective as a draper at collecting weed seeds retained at harvest. This means that harvest weed seed control tactics can be implemented, directing weed seed into the chaff stream to be deposited in a narrow band on the wheeltracks or behind the harvester, rather than spread across the paddock. The stripper front must be set up correctly to minimise grain (and weed seed) losses out the front.
Because so little crop residue goes into the harvester when a stripper front is used, there is no need for a MAV or Powercast stubble spreader attachment, saving on capital and running costs.