Researchers at the University of Otago have found that
streams flowing through integrated sheep and beef farms are
just as healthy as those flowing through organic farms.
The paper found conventional sheep and beef farms had the
most negative impact on waterways, but the conditions of
streams flowing through organic and integrated farms were
similar.
Integrated farms aimed to reduce or eliminate the use of
pesticides, used beneficial pest predators and encouraged
environmentally responsible soil, water and energy
management, researchers said in a statement.
The resulting paper, titled "Responses of stream
macro-invertebrates and ecosystem function to conventional,
integrated and organic farming", was recently published in
the British Ecological Society's Journal of Applied Ecology.
The survey involved students and supervisors from the
university's zoology department, its Centre for the Study of
Agriculture, Food and Environment, the Agricultural Research
Group on Sustainability and the National Institute of Water
and Atmospheric Research (Niwa).
Research fellow Christoph Matthaei said the study focused on
15 streams, five each flowing through conventional,
integrated, and organic non-intensive pasture-based sheep and
beef farms near Amberley, Akaroa, Outram, Owaka and Gore.
Information was gathered on riparian management such as
fencing, stock access, stock presence and regenerating woody
and bank vegetation, which was determined as a percentage of
bare ground, pasture, tussock, scrub and trees.
The different farm management styles were measured on how
stream ecosystems functioned, water quality, biodiversity and
the abundance of pollution-sensitive micro-invertebrate
species, such as mayflies, stoneflies and caddis flies.
The assumption was that organic farming practices would have
the least impact on streams, but Dr Matthaei said the
research found integrated management had a similar effect.
While all the streams were polluted to some extent, those on
conventional farms were most so, while those on integrated
and organic farms had similar levels.
"Integrated and conventional farms received similar
fertiliser and pesticide inputs, but nutrient and pesticide
concentrations of integrated farm streams were generally low
and more similar to organic than conventional farm streams,"
the authors said in their report.
"This may reflect greater care taken over the timing of
inputs by farmers who follow integrated farming
prescriptions."
However, all farm management was impacting on the health of
streams, which were described as "moderately polluted", and
the researchers recommended increased attention to fencing,
riparian management and stream habitat.
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