Will the introduction of nutrient benchmarks help to achieve sustainable milk production systems? A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Environmental Science at the University of Canterbury Nicola Bridget McHaffie Department of Geography University of Canterbury Christchurch, 2012 i Abstract There has been a dramatic expansion of dairying in New Zealand in the last two decades. This has been accompanied by a series of environmental issues around water use and water pollution. This thesis looks at the issue of excess nitrogen and phosphorus lost off dairy farms to waterways using a mixed method approach. Qualitative interviews with dairy farmers and GIS based water quality modelling are employed to explore whether the introduction of nutrient benchmarks would achieve sustainable milk production systems. Two Best Practice Dairy Catchments, Waikakahi in South Canterbury and Inchbonnie on the West Coast, were investigated as the study areas. These catchments are part of an established DairyNZ program. Findings show that nutrient benchmarks do have the ability to achieve sustainable milk production systems in the catchments. It presents the implications and recommendations for the benchmarking project. ii Table of Contents Abstract ................................................................................................................................................... ii Table of Contents ................................................................................................................................... iii List of Figures ....................................................................................................................................... vii List of Tables ....................................................................................................................................... viii Acknowledgements ................................................................................................................................ xi Chapter 1 INTRODUCTION ......................................................................................................... 1 1.1 Thesis statement ............................................................................................................... 1 1.2 Best Practice Dairy Catchments ...................................................................................... 4 1.3 Research aim .................................................................................................................... 6 1.4 Study areas ....................................................................................................................... 7 1.4.1 The Inchbonnie Catchment .............................................................................................. 9 Site description ................................................................................................................ 9 Main environmental concerns regarding Lake Brunner ................................................ 11 1.4.2 The Waikakahi Catchment ............................................................................................ 12 Site description .............................................................................................................. 12 Main environmental concerns........................................................................................ 14 1.5 Structure of thesis .......................................................................................................... 16 Chapter 2 HISTORY AND GROWTH IN THE NEW ZEALAND DAIRY INDUSTRY ...... 18 2.1 Introduction .................................................................................................................... 18 2.2 The dairy industry in New Zealand ............................................................................... 18 2.2.1 History and current structure ......................................................................................... 18 2.2.2 International dairy market.............................................................................................. 22 2.3 Environmental concerns around dairying ...................................................................... 24 2.3.1 Nitrogen ......................................................................................................................... 27 2.3.2 Phosphorus..................................................................................................................... 28 2.3.3 Why are nitrogen and phosphorus an issue in New Zealand waterways? ..................... 30 Environmentally ............................................................................................................ 30 Culturally ....................................................................................................................... 33 Socially and economically ............................................................................................. 35 iii 2.4 Current nutrient management framework under the Resource Management Act (1991) .. ....................................................................................................................................... 36 2.4.1 The Resource Management Act (1991) ......................................................................... 36 2.4.2 Central government management under the RMA ........................................................ 38 2.4.3 Regional council management under the RMA ............................................................. 39 Point source discharges ................................................................................................. 40 Non point source discharges .......................................................................................... 41 2.5 Conclusion ..................................................................................................................... 42 Chapter 3 Nutrient management in New Zealand ...................................................................... 44 3.1 Introduction .................................................................................................................... 44 3.2 Nutrient management through the RMA in Lake Taupo and Lake Rotorua .................. 44 3.3 Industry driven nutrient management ............................................................................ 52 3.3.1 Dairying and Clean Streams Accord (2003) .................................................................. 52 3.3.2 Westland Milk Products’ Environmental Code of Practice ........................................... 55 3.3.3 Nutrient budgets and Nutrient management plans ......................................................... 55 3.4 Nutrient benchmarks ...................................................................................................... 58 3.4.1 Explanation .................................................................................................................... 58 3.4.2 Development .................................................................................................................. 59 3.4.3 Implementation .............................................................................................................. 60 3.4.4 National and international reasons to improve nutrient management through the introduction of nutrient benchmarks .............................................................................. 61 National reasons to introduce benchmarks .................................................................... 61 International reasons to introduce benchmarks ............................................................. 63 3.5 What is a sustainable milk production system? ............................................................. 65 Chapter 4 Methodology ................................................................................................................. 69 4.1 Farmer interviews .......................................................................................................... 69 4.2 Water quality modelling ................................................................................................ 73 4.2.1 The CLUES model ........................................................................................................ 74 Components of the CLUES model ................................................................................ 75 Running the CLUES model ........................................................................................... 79 Calculation of nitrogen and phosphorus losses ............................................................. 79 Calculations of nitrogen and phosphorus concentrations .............................................. 80 Calculation of mitigations.............................................................................................. 81 4.2.2 Scenario One: current water quality .............................................................................. 82 Measured water quality data for comparison ................................................................. 86 4.2.3 Scenario Two: water quality predictions with benchmarks ........................................... 87 iv Water quality values for comparison with predictions .................................................. 89 4.2.4 Methodology for modelling Lake Brunner .................................................................... 92 4.2.5