A review of information on the transportation of dairy effluent through soil and the associated on-farm practices

Politically and publicly it has been decided that water quality and quantity are fundamentally important for the future of New Zealand. While this appears to be an appropriate goal that fits with our Clean Green and Pure NZ slogans it overlooks the challenge that it imposes on the primary production sector. Finding the balance between public expectation (pristine water) and what is realistically achievable and affordable is the tension that dairy farmers are grappling with at present. Effluent management and non compliance with Council rules have become the focus. While concerns existed in the 1990’s about the success of applying dairy effluent to land it wasn’t until 2003 before there was any significant investigation and scientific research. The purpose of this report is to; 1. review the available information on farm dairy effluent management with an emphasis on information that describes what happens to effluent once it is discharged to land, 2. summarise the basic principles and terminology associated with soil and irrigation that are relevant to keeping effluent within the root zone (ie achieving Best Practice), 3. identify the key factors and data that is required to achieve Best Practice, 4. link the findings to existing on-farm systems and provide practical guidance about applying effluent to land and choosing the ‘right’ effluent management system, 5. test the validity of the information and guidance by undertaking a case study, 6. provide information in a format that can used to develop regulations, Fact Sheets or educational material for rural professionals, Councils, AglTO and farmers.