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TECH
@WORK
Spraysaver
WEED-TARGETING TECHNOLOGY ANOTHER STEP IN
LAST SUMMER, I FOUND MYSELF
transfixed by a video of a new sprayer
technology called WEEDit. The system
has the potential to reduce herbicide use
by 85 per cent, saving farmers money or
making it more cost effective to use
higher-strength products to combat
control-resistant weeds. With the world
closely watching agricultural practices,
WEEDit has the potential to demonstrate
farmers’ commitment to applying the
minimum spray required to maintain the
highest productivity.
Developed and commercialized by
Dutch company Rometron, WEEDit relies
on pulse width modulation technology.
Its sensors, placed at one-metre intervals
along the nozzle boom, focus a red LED
light that pulses 44,000 times per second
on the ground 65 centimetres ahead.
When the light hits green plant material,
it causes the chlorophyll in the leaf to
phosphoresce. This process emits a faint,
near-infrared light that is picked up by the
sensors. A signal is then transmitted to a
solenoid, causing the spray nozzle to open,
precisely targeting the plant. If no further
signal is detected, the nozzle closes after
five nanoseconds.
Each sensor is divided into five channels
that individually survey a 20-centimetre-
wide strip and control one of five spray
nozzles. This ensures that the system
accurately surveys the ground it passes
over. A full 36.5-metre system consists of
36 sensors and 180 spray nozzles.
Importantly, the pressure at each nozzle
remains consistent regardless of speed.
Touted as being able to work effectively at
up to 25 kilometres per hour, the system
doesn’t hinder sprayer efficiency. As well,
the technology works for pre-seeding and
post-harvest burndown, as it will spray
any green material.
Travis Albrecht farms near Schuler, and
was the first owner of a WEEDit system in
Canada. He saw the system in action on
the Facebook page of an Australian farm-
er. Initially developed for hot-water weed
control on Europe’s cobblestone streets,
the system was first used for agricultural
purposes in Australia and South America
before coming to North America. Albrecht
retrofitted his John Deere self-propelled
sprayer and saw dramatic reduction in his
herbicide use in 2017. After harvest, he
loaded his tank with water and glyphosate
to determine how WEEDit product usage
compared to blanket spraying.
“We should’ve been empty at 87 acres,
and we were spraying consistently over
700 acres,” said Albrecht. That’s one-
eighth the amount of chemical used, or
an 87 per cent reduction. On a 2,500-acre
farm, spraying one litre per acre of
glyphosate at $6.50 per litre, that’s a
saving of over $14,000. This might allow
money to be budgeted for a tank mix that
better controls problem weeds such as
glyphosate-resistant kochia or Canada
thistle. Along this line, Albrecht added
Lontrel, a herbicide that normally costs
him $20 per acre, to his tank mix.
Although crop protection products are
fairly inexpensive, Albrecht believes this
will change. “There will be some new
chemicals that they’re going to come out
with, and instead of being $5 to $6 an
acre, it’s going to be $10 or more, which is
going to make this technology even more
valuable.”
Last fall, Albrecht conducted WEEDit
demonstrations using water-sensitive pa-
per to assess spray coverage. The system is
guaranteed to sense weeds as small as one
centimetre square, and Albrecht said even
weeds half that size triggered the nozzles.
As well, the WEEDit monitor allows the
operator to adjust the margin to spray
from 10 to 50 centimetres on either side of
the weed to compensate for wind drift.
Sprayer technology specialist Tom Wolf
attended a demonstration in Saskatch-
ewan and describes the equipment as
“future ready.” “I think we are about to
enter a sensor revolution in ag,” said Wolf.
“Our ability to identify areas that should
be treated in a different way is going to get
easier. A system like [WEEDit] is perfectly
positioned to prepare us for an in-crop,
weed-detecting algorithm.” That is, in fu-
ture, such a system would be able to spray
only the weeds within a standing crop.
Some questions remain as to how the
system would work with residual chem-
istry often used in pre-seeding spray
applications to control weeds that emerge
along with crop seedlings. Spot spraying
would not produce uniform residual activ-
ity, Wolf pointed out. “It leads people to
think about other things like having more
than one tank or having direct injection of
chemical,” he said. “You might have one
mode of action broadcast but have one
Sensors on theWEEDit nozzle boom trigger spray
nozzles that precisely target green plant material,
decreasing the amount of chemical required for
maximum effect.
Images:WEEDit
THE SENSOR REVOLUTION
Spring
2018
Grains
West
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