March 2019 - 18

GLOBAL PERSPECTIVES
Variable rate technology
pays off in the Netherlands
By Melanie Epp
CONTRIBUTING WRITER
U
niversity
of
Wageningen
researcher Corné Kempenaar and
his colleagues at the Department
of Agro Systems Research conducted
a study to assess the cost benefit of
adopting five variable rate application
(VRA) technologies in potato production.
Results, which were published in
Potato Research last year, show that VRA
technologies do pay off under practical
conditions in The Netherlands. The five
VRA technologies that produced the
most rewarding results were planting,
soil herbicide weed control, nitrogen
side dressing, late blight control and
haulm killing.
VRAS ANALYZED
Although the researchers analyzed 13
potential technologies, they ended up
selecting just five, which they selected
based on proof of concept and on-farm
test results. Each of the five VRAs uses
spatial data in the form of either soil
maps or biomass index maps.
The first two VRAs, planting and soil
herbicide weed control, involved the
use of soil maps, which were used in
combination with other information
to create a variable rate map. The
other three used crop biomass index
maps, also in combination with other
information to make a task map.
" This multiple use of data helps
to make the cost-benefit assessment
positive because costs can be spread over
several actions and investments will pay
off faster, " the report concluded.
Optimal depth and spacing of tubers
depends on a variety of conditions,
including soil, climate and tuber
variety, as well as the objective of
the farmer. Using modern planters,
growers are able to vary planting
density to match conditions.
" In the EU IoF2020 project, we studied
variable rate seeding of potatoes based
on lutum content of the soil, distance
to tram line of the sprayer and yes or
no shading by obstacles like trees, " said
Kempenaar in the paper. " Where lutum
content of the field was relatively low
and/or shading by trees was expected,
seed spacing was larger and vice versa. "
Precision agriculture has also
promised to help farmers reduce
herbicide use. The researchers evaluated
the use of variable rate applications
of herbicides in potatoes by looking
at soil maps. Specifically, they found
that soil herbicide applications could
be reduced in zones where soil organic
matter and/or lutum content are low as
they are more effective in these zones.
Their research showed that reductions
of 20 to 40 percent were possible.
Of the five technologies, potato
haulm killing was the most widely tested
in on-farm research. In The Netherlands,
standard practice for killing the potato
canopy is to apply a defoliant herbicide.
Using crop biomass index maps to
apply defoliants more prescriptively
resulted in reduced herbicide use of
20 to 47 percent. Calculating for the
average and considering the average
cost of commonly used products, the
researchers found that costs could be
reduced by as much as 90 percent if
satellite images are available.
For both VRA seeding and soil
herbicide applications, the researchers
found that a 2 to 4 percent yield increase
For the full report, visit bit.ly/VRAReport
18
Spudman.com
was needed in order for the grower to
see a cost benefit.
" VRA fungicide trials
in potato showed
reductions in herbicide
use between 20 and
30 percent. "
- Corné Kempenaar, University
of Wageningen researcher
There was a cost-benefit ration seen
in VRA fungicide use for managing late
blight in potato as well. Dutch farmers
typically apply fungicides every 5
to 10 days throughout the growing
season to prevent late blight infection
and damage. Using crop reflection
sensors that assess aboveground leaves
and stems, however, producers can
select more precise dosage. The more
biomass present, the more fungicide
is needed.
" VRA fungicide trials in potato
showed reductions in herbicide use
between 20 and 30 percent, " Kempenaar
wrote. " VRA fungicide use in potato has
a positive cost-benefit ration thanks to
multiple applications (84 vs 25 € ha -1). "
Using VRAs
for
pesticide
and
N-fertilizer, growers averaged about 25
percent in savings when compared to
the reference standard practice.
It should be noted that the report
was clear that conclusions are based
on the assumption that the costs of
sensor data are shared over different
variable rate applications and no extra
investments are needed in sprayer and
spreader technology.
http://www.bit.ly/VRAReport http://www.Spudman.com
March 2019

Table of Contents for the Digital Edition of March 2019
