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Published: 2009-09-17 00:00:00

Farmers involved in a three-year trial in South Waikato have been able to improve nutrient efficiency and make reductions in the amount of nutrients that will leave their land in future years, says a new report from Environment Waikato.

The knowledge contained in the report on the independent evaluation of the Integrated Catchment Management (ICM) trial in the Little Waipa and Waipapa catchments has been fed into a wider project in the Upper Waikato River catchment, and is being made available on EW’s website for all farmers to access.

ICM has involved EW field staff working one-on-one with farmers in the two catchments to build a better understanding of farm systems and the core contributing factors involved in reducing nutrient loss from farms.

EW’s ICM coordinator Ross Abercrombie said the project’s findings would provide very useful information on ways to reduce the effects of farming on the environment.

"ICM focused on reducing nitrogen leaching and phosphorus runoff from farm activities. The project has shown that, by working one-on-one with farmers, we have been able to help them to make some inroads into reducing the amount of nitrogen that will leach from their properties into waterways in future years. EW staff worked one-on-one with about three quarters of the farms in the two catchments.

"We haven’t been able to achieve as much of a reduction as we’d ideally like in the two catchments but it’s a good start, and we have gained a lot of information on methods and ways of working with the farming community to address such issues.

"The lessons learnt in Little Waipa and Waipapa are currently being fed into a wider project we’re involved with in the Upper Waikato hydrolakes catchment, alongside DairyNZ, Ballance Agri-nutrients and Fonterra. This project is aimed at understanding more about what makes a farm more nutrient efficient and what the costs or benefits of reducing nutrient loss are," said Mr Abercrombie.

"The very positive relationships the ICM project has built with the agriculture industry as a whole has led to this opportunity to work together on further developing our understanding of the challenges and options. We expect to use this experience in drafting the regional sustainable agriculture strategy."

Data modelling indicated that reductions in the annual amount of nitrogen leached were typically between 5 and 10 kilograms per hectare, from actions most farmers would agree to. The modeling indicated that 20 dairy farms in the Little Waipa catchment were collectively able to reduce nitrogen leaching by around seven tonnes a year.

However, the ICM report said further reductions would likely be needed to maintain current water quality in the Waikato hydro lakes and that further intensification of farms, or conversion of new forestry and sheep/beef farms to dairy farms, could offset savings identified in the study. The current focus of ICM work is to find ways to further reduce nutrient losses from farms while ensuring profitability is not eroded.

"Once we have completed the new Upper Waikato Nutrient Efficiency Study later this year, we will be working in collaboration with industry groups to ensure the lessons we have learnt are shared with the wider farming sector, and to apply those lessons in looking to reduce nutrient losses further.

"The findings from the ICM pilot project and the current Upper Waikato study will also help EW and rural stakeholders to develop plans to ensure that agriculture continues to improve its environmental impact and maintain its central place in the regional and national economy in the long term," said Mr Abercrombie.

The full ICM report is available online at