Irrigation efficiency woes
It
might seem like common sense that increasing the efficiency
of irrigation would save water, but the equation isn't that
simple.
In a Policy Forum published today in Science,
international experts argue that increasing efficiency
simply results in more water being used on farms and less
being returned to the environment.
As Dr Brent Clothier from Plant & Food Research explained to the SMC, the irrigation efficiency paradox is that "any water saved by the individual farmers does not - global empirical evidence shows - serve to reduce water takes across the entire catchment". Instead, more people end up using the water. "So, individually, the farmers might well use water efficiently, but the total extraction of water by the whole community of farmers across the catchment is not reduced."
Not only is the water not 'saved' but it also reduces the amount of water being returned to the ground through leaks or other means. Dr Leanne Morgan from the Waterways Centre for Freshwater Management at the University of Canterbury told the SMC: "the reduced groundwater levels can impact spring flows and require farmers to lower wells (at considerable cost) to access the now deeper groundwater". She says this is an example of the "unintended consequences that might arise from irrigation efficiency initiatives designed to reduce water use."
We don't tend to think New Zealand has issues with water scarcity, but Professor Troy Baisden from the University of Waikato says because of the rapid expansion of dairy, wine and fruit into drier regions over the past few decades, "our freshwater available for irrigation is already fully allocated or over-allocated in these regions".
In an unrelated piece, Dr Mike Joy from Victoria
University of Wellington wrote on Newsroom that
irrigation dams like the one proposed for Waimea River in
Nelson are a "dumb idea" as the "lock us all into a
high-risk, high-cost, high-impact water storage system". For
those upset at the Government's stance on irrigation, a
recently-shelved irrigation scheme in the Waimate District
has been revived by private
backers.
The SMC gathered expert reaction on the
Science article.
Quoted: Newsroom
"What we
would like to see is the beginnings of a whole new industry
built on sustainably-grown tōtara.
We would like to see
more employment, we would like to see high quality jobs in
Northland."
Scion’s general manager of research
and investment Russell Burton on the viability of growing tōtara for
timber.
Samurai to slay stink
bug
Ramped up biosecurity controls have
done a good job of keeping the dreaded brown marmorated
stink bug out of the country. But should the
one-dollar-coin-sized bugs gain entry to our greener
pastures, the Environmental Protection Agency (EPA) has
pre-approved the release of their traditional foe: the
pin-head sized samurai wasp.
The bug has
decimated crops in North America and poses one of the most
significant biosecurity threats to our agricultural
sector – particularly the kiwifruit and wine
industries. It also has the potential to attack native plants like
karaka and kowhai.
The EPA’s decision means they are
only able to release the non-native samurai wasp if stink
bugs slip through the border and invade. The samurai wasp is
not the only biocontrol agent we have at our disposal. The
EPA has previously released other parasitic wasps to control
the agricultural pests like clover root weevil and coddling
moth. However, this is the first time the EPA has given
pre-approval to release a species into the country ahead of
a threat, an advance the agency’s organism manager Stephen
Cobb told Newsroom was
“ground-breaking”.
“Bio-control is increasingly
what the primary sector and people focused on conservation
are looking at as it is considered possibly a bit more
environmentally friendly than the use of pesticides or
herbicides or chemicals,” said Cobb.
New Zealand
winegrowers biosecurity manager and emergency response
manager, Dr Edwin Massey, who is also a member of the Brown
Marmorated Stink Bug Council previously told RNZ the samurai
wasp is both a surveillance and control tool.
“The wasp
favours brown marmorated stink bug eggs over any other stink
bug egg, so releasing it only when there is a stink bug
incursion is exactly the right thing to do.”
The
Ministry for Primary Industry’s Dr Catherine Duthie told
Newsroom: “We’ve got quite an arsenal lined
up. This parasitoid [samurai wasp] is just one of those
tools.” MPI is also preparing pheromone-laced traps to
lure the stink bugs, a spray to kill them, and trained dogs
to locate areas with bug infestations.
“Essentially the
parasitoid is a mop-up measure to make sure that we don’t
get any further adult or nymph brown marmorated stink bugs
into the population.”
The decision was covered by local media.
Video workshops go
South
In October, the Science Media
Centre will take its popular science video making workshops
to Christchurch and Dunedin.
These video
workshops (produced in collaboration with Baz Caitcheon) focus on giving
scientists the tools and skills to communicate their
research in short videos aimed at an online
audience.
Producing short videos using the
high-definition camera built into your smartphone or tablet
has never been easier. We’ll show you to how to develop a
video concept and give you tips on the best ways to shoot,
edit and distribute your video content. In the weeks
following, Baz will mentor you to help you produce your
first science video.
The workshops are free to attend, but
limited to 15 places. This is a competitive application
process – the best applicants will be selected based on
the video concepts outlined in the application
form.
• Christchurch, University of
Canterbury
WED, 24th October, 9.00am
– 1.00pm
• Dunedin, University of
Otago
THURS, 25th October, 9.00am
– 1.00pm
APPLY
HERE