Friday, March 29, 2024

Deer’s water effect being studied

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A unique survey of hill country waterways hopes to link onfarm deer management practices with water quality. The Hitting Targets research project is a long-term, multi-disciplinary investment by DEEResearch, a joint venture of AgResearch and Deer Industry New Zealand that aims to lift the productivity of deer farms.
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The waterways project is in the first year of a five-year survey of water quality in creeks and streams on high and hill country deer farms. 

It is thought to be the first time a NZ drystock farming sector has tried to put a number on its impact on waterways at a detailed farm level.

It is a case study experiment where repeated monitoring of a number of catchments over time will be used to build up a database of how water quality is influenced by deer farm management.

DINZ environmental stewardship manager Lindsay Fung hopes the findings will link onfarm deer management practices with water quality.

“This will enable us to advise farmers and regional councils on the best practices and policies for reducing the impact of deer on the environment. 

“At the moment we have good anecdotal information about what works best but we need to support this with some hard data,” Fung said.

Project leader and AgResearch farm systems and environmental researcher Dr Jane Chrystal said the research team aims to build a picture of the impact of deer on different types of high and hill country streams. 

Some streams start in the undeveloped tops and finish up in more intensively farmed blocks. 

By monitoring water quality and the length of the stream the team can measure where nutrients increase or decrease along its course.

Chrystal said wallowing deer create unique challenges because that is associated with phosphorous and sediment losses into waterways. 

“All waterways have base levels of nitrogen and phosphorous that occur naturally so when we monitor a farm stream we need to ask of the nutrients we measure, how much do deer contribute?”

To answer that AgResearch and farm-owners are monitoring three properties in the South Island and two in North Island this year, with five more farms to be introduced next year. 

The research team will trek into catchments on the farms every six months to gather water samples along the course of each monitored stream.

The team will also assess stream bank condition using a monitoring and rating system developed by AgResearch for the project. 

From the condition of the stream bank the researchers expect to be able to predict a site’s potential to add contaminants to the waterway. 

By sampling water at its source in the high country the base or background nutrient levels could be determined before the water was influenced by farming. 

“These streams are on the big high-country blocks where farmers might put hinds out for fawning, not intensively-stocked, high density areas. 

“We’re talking matagouri and scrub canyons – these aren’t lovely streams that people are swimming in,” Chrystal said.

Participating farmers have been asked to keep records detailing when stock are moved in and out of paddocks and the number and class of stock involved. 

Fertiliser records are also needed.

The farmers will also be taking water samples from the bottom of the catchment every month and they, together with those collected by the technicians, will be tested for suspended sediments, phosphorus and nitrogen as well as for E coli as an indication of faecal contamination.

Chrystal said it was too soon to comment on the results to date because a picture of the actual quality of the water would not be known until a number of samples had been taken over time. 

While other sectors had different waterway issues, citing dairy as an example with nitrogen leaching, it would be useful to have a broad picture of NZ agriculture. 

She hopes the sheep and beef sectors will soon have funding to follow the deer industry’s lead. 

“Different species have different impacts on the environment so we need to find solutions for the impacts that are deer-specific. 

“But then again, many deer farms run sheep and beef so it would be helpful to know what impact they have as well.” 

With the five extra farms for the 2019 monitoring yet to be selected the AgResearch team is keen to hear from interested farmers.

Anyone interested should contact geoff.asher@agresearch.co.nz

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