Research: Southland farmers must speed up adaptation to climate change
Southland farmers are being told nitrate leaching could significantly increase as a result of the changing climate. A report released today, prepared by Manaaki Whenua Landcare Research for Deep South National Science Challenge, says nitrate leaching in Southland might be higher and more variable with climate change. Principle investigator in the research, Anne-Gaelle Ausseil, said researchers were surprised that extreme weather events were projected to have such a strong impact on nitrogen leaching. "Because these modelling results were unexpectedly high, and were only modelled in one location in Southland, this needs further investigation across the region and for different farm types," Ausseil said. READ MORE: * Australia vs New Zealand: Climate report casts doubt on Boxing Day test's future * 'Worst fears confirmed' as hunters release their own dead deer survey after Molesworth 1080 drop * Auckland's poorest to suffer most in climate change Annual leaching in Southland was modelled to increase significantly because of "more spring rain and more frequent extreme rainfall events," the research report says. Nitrogen is a key nutrient to grow grass on farms, but when there is more in the soil than plants can use it is at risk of leaching into groundwater, or runs off into rivers and streams, degrading water quality. Manaaki Whenua is a crown research institute company, based in Lincoln. The report used case studies in Hawke's Bay, Southland and Waikato. In the Hawke's Bay case study, year-to-year leaching variability was most extreme in free draining soil. Other implications for Southland primary industry operators included an a more pronounced risk of severe heat stress for animals. "Heat stress will be an increased risk for animal health, with about two additional weeks of risk for moderate heat stress by the 2090s," the research report says. More shade and shelter will be needed. The report also indicated changes to pasture growth. "Change to pasture growth is likely to vary by location, but a marked shift in seasonality with increase in growth in late spring/early summer is likely, with a decrease in late summer. Analysis with two models both gave consistent results," the research report says. Ausseil said the study looked at the impact of overall climate trends, but was not able to calculate the impact of all risks. "Extreme events like hailstorms and damage from insects are also likely to increase under climate change conditions, but it is difficult to quantify the additional measures needed to respond to these events." "We hope this research will further encourage long-term strategic adaptation, such as diversifying cultivars, shifting sowing dates and planning additional shade and shelter." . While the climate change projections were not new, no one had looked at how they might impact on primary production and water quality before," Ausseil said.