Tuesday, December 5, 2023

Catchment groups changing the conversation in Southland

Neal Wallace
A key factor behind the proliferation of catchment groups in the province is the involvement of Thriving Southland.
Reading Time: 3 minutes

Southland has 35 community catchment groups but the challenges they face are far from uniform. 

Members of four of the groups told the South Island Dairy Event in Invercargill in June about their activities, which address water quality and greenhouse gas emissions, looking at the contribution from landscape, geology and farm management.

They all noted that catchment groups are as much about social and community cohesion and interaction as environmental improvement.

A key factor behind the proliferation of catchment groups in the province is the involvement of Thriving Southland, a community-led entity that provides resources, administration and support through a network of five co-ordinators.

Simon Topham, a member of the 60,000ha Hedgehope-Makarewa Catchment Group, said its topography includes steep hill country, native bush, peat bogs, horticulture, coal mines and cultivated flat land.

By mapping the catchment they can extrapolate the impact of activities on water quality.

A case study on four farms assessed soil erosion, topography, hydrology, particulates, nitrites, sediment and nitrous oxide, giving an understanding of farming impacts on the environment.

“The conversations have changed from not knowing, to knowing and asking ‘What can we do?’”

The Waimatuku and Lower Aparima Catchment Group incorporates 636 farms, and group member Luke Templeton said community activities, including stream walks and water testing, help them understand their impact on waterways.

Catchment group field days in Southland. The region has 35 community catchment groups but the challenges they face are far from uniform.

The use of water testing has doubled in the past three years, identifying high risk areas.

Templeton said surveys revealed a large percentage of farmers have adopted Farm Environment Plans, which shows the level of commitment to improving the environment.

Other activities include experimenting with sediment trap design to determine which is the most effective.

Templeton said the momentum from these projects is providing a foundation for the future.

The Dipton Catchment Group is looking at the levels of on-farm agricultural greenhouse gases and options to reduce them.

Group member Charleen Withy said the social aspect of uniting the community on projects such as this is of equal importance.

Last November the group decided to front-foot the climate change issue by launching a project to measure on-farm greenhouse gas emissions and determine if they could become carbon neutral.

This involved case studies on five farms – two dairy and three sheep and beef.

From that they could assess the viability of tweaking or changing current systems or adapting technology to reduce them.

“We felt this was relevant given the topic of climate change, emissions trading scheme and He Waka Eke Noa,” she said. 

Overseer was used to measure nutrient losses, biogenic, nitrous oxide and carbon dioxide emissions as carbon dioxide equivalents. It did not include fossil fuel emissions.

The FarmX programme was used to assess the economic impact of four farm system scenarios.

Charleen and Chris Withy milk 440 cows on 143ha, rearing 115 replacement heifers and grazing cows off farm.

A draft assessment of their farm reveals emissions of 2183t of CO2 and 65kg N/ha/year.

Representatives from four Southland Catchment groups spoke at last month’s South Island Dairy Event. From left, Charleen Withy, Ginny Crawford, Luke Templeton and Simon Topham.

The four scenarios measured were: installing a herd home, which would increase emissions to 2186t but lower nitrogen loss to 55kg/ha; a lower stocking rate, 2060t and 54/kg; lower replacement rates 2157t, 55kg; and growing 20ha of oats for milk 1770t and 67kg.

A herd home would increase earnings before interest and tax (EBIT) by 1%, a lower replacement rate by 3.2%, but lower stocking rates and oat milk would decrease EBIT by 5.7% and 23.8% respectively.

Options for sheep and beef farmers included forestry, changing the sheep to cattle ratio, incorporating dairy support and selling lambs as store.

The issue on the Orauea River in Western Southland was sediment affecting water quality, the source of which was not previously obvious.

Ginny Crawford from the Orauea River Catchment Group said research determined that 59% of the geology in the 48,300ha catchment is mud stone, which is weak, has a high clay content, moves easily and creates sediment on which E coli can piggyback.

This has a significant impact in the quality of the Orauea River.

Crawford said the soil in the catchment has been mapped to identify high-risk areas, which include 3400 watersheds.

Landowners can click on an online map to find the soil on their farm, which helps with management.

The group holds field days to promote land management using tools such as fencing and planting.

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