What’s the latest in targeted tillage for conservation farming systems?
with Stuart Watt, physicist and software engineer, University of Western Australia
Conservation farming practices have kept tonnes of topsoil in place, reduced drought risk, and enabled many businesses to expand and increase their profitability. The downside is the heavy reliance on herbicides for weed control.
Dr Stuart Watt, a physicist and software engineer at The University of Western Australia’s Centre for Engineering Innovation: Agriculture & Ecological Restoration (CEI:AgER), says that targeted tillage machines for use in bare paddocks and row crops will give growers additional, non-herbicide options for weed control.
“The latest tillage tool we have developed follows a similar concept to the Weed Chipper that was invented a few years ago, combining weed detection sensing technology with a mechanical chipping action for weed control,” he says. “The new tool is for inter-row weed control in wide-row crops such as cotton, corn and sorghum, and is designed to ‘dig’ out weeds with minimal soil disturbance.”
There is good evidence across various soil types that intermittent and shallow cultivation does not damage soil structure or increase erosion risk.
“For the inter-row machine, we have invented a mechanism that dips a small ‘shovel-shaped’ tillage blade just a few centimetres into the soil to flip out the weeds as they are detected using existing commercial sensors,” says Stuart. “Operating speeds are between 12 and 18 km per hour, which generates a highly effective action to dig out hard-to-kill, and potentially large, weeds over 50 cm in diameter. The tool can invert weeds much larger than the size of the tillage blade.”
This technology aligns well with the WeedSmart Big 6 strategy, offering non-herbicide weed control in two key cropping settings without compromising the benefits of conservation farming.
This year, Geraldton is hosting WeedSmart Week on 29 and 30 July, showcasing how growers can develop a profitable farming system using the WeedSmart Big 6 framework to make sure that weeds are not calling the shots.
What situations does the inter-row targeted tillage prototype machine operate in?
Weeds that survive herbicide treatments can take advantage of the lack of crop competition in wide-row crops such as sorghum and cotton, thriving on the moisture available in the inter-row to compromise crop yield and set large quantities of seed.
This new prototype machine is designed to mechanically control weeds that persist in the inter-row region during the growing season. It is suited to low-density weed control in minimum or zero-till farming systems, targeting herbicide-resistant weeds before they set seed.
Operating at speeds between 12 and 18 km/hr, the tillage blade has a passive entry into the soil, leaving small divots and extracted weeds. The machine can operate around the clock if necessary, uninhibited by weather conditions that would typically restrict herbicide applications, such as inversion layers or high winds.
How does the prototype machine work?
The proof-of-concept 2-row, 7-tyne prototype is designed to disturb the soil as little as possible. Each tyne holds a motorised active tillage blade that sits above the ground in a standby position as the tractor moves along the rows. On the prototype machine, each tillage blade is 200 mm wide, and each pair overlaps by about 50 mm to provide full coverage of the inter-row width.
The prototype uses one WEED-IT sensor per inter-row space to detect weeds. When a sensor detects a weed upstream of the tool, it triggers a small electric motor to turn the tool, dipping it into the ground to scoop out the weed. When the blade reaches its maximum depth, the resistance from the soil, coupled with the forward momentum, returns the blade to its standby position, ready to trigger again. This mechanism allows the prototype to be driven faster without significantly increasing the motor loads, and each targeted tillage action takes less than half a second.
The system is all electric, with the proof-of-concept prototype powered by a 3-phase generator mounted on the implement frame. This provides the energy to run the sensors and motor drivers on each tyne, as well as on-board computers, GPS and safety systems. The team has found the sweet spot where the tillage blade digs deep enough to remove weeds and damage the roots, without creating an unnecessarily large divot or placing excessive load on the electric motors.
What new features will be added to make it a commercial reality?
UWA CEI:AgER’s Mechanical In-Crop Targeted Tillage Project, funded by the Australian government’s Department of Agriculture, Fisheries and Forestry, developed this pre-commercial scale rig with high technology readiness for row cropping situations. Industry partner Demagtech is working with UWA to further advance and commercialise this new tool and the Weed Chipper.
Having demonstrated that the system is an effective weed management tool for wide-row crops, the team will now finesse the design and work with Demagtech to bring the technology to growers.
Some of the planned modifications are:
- Swapping to weed detection (RGB) cameras to differentiate between crop plants and weeds, i.e. ‘green-on-green’ detection.
- Developing systems to aid with camera/sensor visibility to facilitate use throughout the crop growing season.
- Adding height control to each tyne to keep each tillage blade at the correct height above the soil surface.
- Scaling down the servo motors on each tyne to be more compact, lightweight, cheaper and power-efficient.
- Replacing the generator with the capability to plug into a tractor or a robotic platform with onboard or solar power.
The CEI:AgER Project team includes A/Prof Andrew Guzzomi (Project Lead), Adj. Prof Michael Walsh (Senior Investigator) and Dr Stuart Watt (Research Fellow).
More resources:
Is mechanical site-specific weed control a fallow management option?
