ERADU farmer Rob Kitto has slashed his chemical bill from $100,000 to $10,000 a summer and reduced his impact on the environment by using spot-spraying weed control technology.
Mr Kitto turned to the high-tech weed eradication system four years ago to help tackle melon vines which had become an issue on his property during summer, particularly after summer rains.
Sensors mounted on the machine identify the green colouring of each weed and directly targets them with chemical, eliminating the need for blanket-spraying.
“Because it only sprays the green, there is a huge saving on chemicals which is good for us, good for our budget and also good for the environment as we are only using the chemicals that we absolutely need at the time of spraying,” he said.
Mr Kitto farms 8000 hectares with half wheat, half lupins, grown on yellow sand plains east of Geraldton, Western Australia, where an average rainfall is 400mm a year.
The Grains Research and Development Corporation (GRDC) has been supporting research to optimise the performance of weed detection systems, through better understanding of chemical and water rates, optimal sensor height, speed and correct nozzles.
“Before we invested in a WeedSeeker we would go out and blanket spray the whole field and would be spending up to around $100,000 a year on summer spraying,” Mr Kitto said.
He is now able to hit each weed with 2.5 times the amount of spray he previously used when blanket spraying and still only use one-tenth of the total chemical he used previously.
“That way you are going to hit them and kill them and you can move on, because there is nothing worse than having to go back and spray a weed again.”
Mr Kitto does all of his of his spraying at night to avoid the summer temperatures, which can reach 50 deg C, and can make spot-spraying extremely difficult.
“When we were manually spot-spraying we were only spraying about 50 per cent of what was there and the other half was sneaking through because we weren’t seeing it or it was too dark.
“Now with the camera technology we can sit back and relax in the cab with the auto-steer and the stereo going and stay awake knowing it will go up and down and spray all of the green plants there for us.”
He normally sprays 700ha a night at a spray rate of 100L/ha.
By trying to catch the weeds before they reach roughly the size of a dinner plate, he can use a lower spray rate. However, he can now afford to go back and forth over the same country three or four times over summer and still save money on what he used to spend.
Mr Kitto said the major drawback of the system was its price, costing $215,000, a factor meaning he had been hesitant for several years before deciding to invest.
“The initial shock disappears within the first year of using the WeedSeeker and you physically can see how good it is how it is killing the weeds and you just know that you are not wasting all of that chemical.”
He has set his it up on an old SP boomspray. The high clearance and narrow wheels allow him to desiccate even late weeds in a ripening wheat or lupin crop, as long as the crop is 90 per cent ripe and the weeds are still green.
Although he does not regard his sowing method as zero-till he described it as “very minimum till”.
“We don’t like to disturb the soil any more than we absolutely have to because it is very fragile, as it is sand and very wide open.
“We do get some strong winds coming through here that will blow the sand if it is left too bare.”
By effectively spraying out the weeds he can also retain more trash on the surface.
“It allows us to handle all of our stubble residue from the previous harvest at seeding time if there aren’t any summer weeds that have got through,” he said.
“If you let your vine weeds grow too big and you have to go and burn your stubble residues then it bears off the sand and that’s not helpful to anyone.”
More information on the use of spot spraying technology is available at www.grdc.com.au
