High residue farming with a stripper front and a disc seeder efficiently captures and stores soil moisture, and growers are finding the system can be tweaked to also improve weed management.
An increasing number of growers in the northern region are seeing early confirmation that the system works and there is building scientific evidence that they are on the right track with the adoption of narrow row sowing with single disc planters, combined with a stripper front and either a chaff deck or chaff line at harvest.
Peter and Kylie Bach, Kurilda Ag, Pittsworth use a Shelbourne harvester front and Emar chaff deck to conserve stubble and put weeds in their place.
AHRI and WeedSmart agronomist Greg Condon says this system is providing growers in the northern grains region with opportunities to plant and grow crops that would otherwise not be possible.
“Harvest weed seed control is a useful tactic against many of the key weed species in the northern region,” he says. “We now have scientific data to show that, with correct harvester set-up, stripper fronts and drapers can be equally effective at collecting weed seeds at harvest. The advantage of the stripper front is that the vast majority of the crop residue remains as standing stubble in the paddock. This means the harvester does not have to deal with enormous amounts of plant material and there is so little straw going through the machine that choppers and spreaders have much less work to do.”
“When a chaff deck or chaff line chute is attached to the harvester, the weed seed is separated from the grain with a small amount of chaff, and deposited either on the controlled traffic wheeltracks or in a narrow band behind the harvester. These weeds can then be subjected to targeted control tactics applied to a very small percentage of the paddock area.”
A chaff deck attached to the harvester separates the weed seed from the grain, along with a small amount of chaff, which is deposited on the controlled traffic wheeltracks.
For some growers, like Peter and Kylie Bach farming at Pittsworth on the Darling Downs of Queensland, using the stripper front and chaff deck combination in their cereal crops has gone a long way toward solving their problems with volunteer crop plants from previous seasons.
“The standing stubble has given us planting opportunities for summer crops that would not have been possible after a conventional harvest,” says Peter. “Barley stubble provides an excellent environment for planting mungbeans and when the mungbeans are harvested, the paddock has much better ground cover with the previously-standing cereal stubble being retained on the soil surface.”
The stripper front leaves most of the stubble standing in-situ, meaning much less material needs to be processed in the harvester.
Peter and Kylie find that the barley stubble can persist for a few seasons after the growing season, providing soil moisture conservation benefits in their summer cropping program.
The ‘strip and disc’ system ticks off three of the WeedSmart Big 6 tactics for managing herbicide resistance – crop competition, harvest weed seed control and diverse rotations.
“When weed control is integrated into an agronomic package it is possible to achieve some real synergies in the system – achieving more than just the cumulative benefits associated with each of the parts,” says Greg. “After a few years, there is a combination of standing and residual stubble in the field and stubble load is managed through the sequencing of different crops, without ever leaving the soil bare.”
The ground cover benefits of cooler, moist soil opens up the possibility of sowing early and growing longer season crops, and even double cropping is some environments. There is also better nutrient cycling and improved soil biota activity.
Tall stubble left after the stripper front harvests the crop and a line of chaff left behind the harvester concentrates any weed seed collected during harvest in this narrow and well-shaded band.
While the stripper front has several benefits and efficiencies over the conventional draper, these benefits are not likely to support a change-over until existing machinery is due for replacement, according to an economic study by John Francis, Holmes and Sackett. A draper can achieve many of the same standing stubble benefits and harvest efficiencies as the stripper front if the harvest height is set at 40 to 60 cm. For both options to be effective for weed seed collection the crop competition must be strong to force weeds to set seed high in the canopy. Without strong crop competition, harvest weed seed control generally relies on cutting as low as possible at harvest.
Grower experience suggests that stripper fronts have a distinct advantage when it comes to picking up fallen or lodged crops and weeds.