Irving, Charlotte2017-04-202017-04-202016https://hdl.handle.net/10182/8028Public and political concerns regarding the impact of agriculture on water quality have heightened in recent years in response to the declining water quality of New Zealand waterbodies. In response, Variation 1 of the Canterbury Land and Water Regional Plan requires nitrogen leaching from dairy support land in the Selwyn Waihora catchment to decrease by 22 percent beyond good management practices by 2022. Consequently, dairy farmers that own dairy support land within this catchment are under significant pressure to implement a system that meets the nitrogen constraints. This research uses a farm systems modelling approach to investigate the implications of nitrogen regulations on the performance of four dairy support farms in Selwyn Waihora. This research will help assist dairy support farmers in making informed decisions when considering how to mitigate their nitrogen leaching losses while not undermining the performance of their farming business. The outcome of this analysis is that nitrogen loss regulations are likely to reduce stock numbers on dairy support farms. Therefore, it is likely that owned dairy support land will be unable to meet the purposes it was purchased for; to attain direct control of livestock condition to enhance the performance of the overall dairy enterprise. Nitrogen regulations are also expected to reduce the operating profit of dairy support farms. This study reiterates the importance of farmer preference in selecting mitigations as some DSL farmers prioritise factors such as control over stock higher than profit levels. Overall, there is no ‘one size fits all’ approach to mitigating nitrogen leaching from dairy support farms, as these factors need to be considered on a farm specific and farm system basis.enwintering systemsnitrogen regulationCanterbury Land and Water Regional Plannitrogen mitigationdairy support landSelwyn DistrictTe WaihoraFarmaxOverseer TMDissertationANZSRC::070101 Agricultural Land ManagementANZSRC::070105 Agricultural Systems Analysis and ModellingANZSRC::070106 Farm Management, Rural Management and AgribusinessANZSRC::070107 Farming Systems ResearchQ112931098