title: Modelling pastoral farm systems--scaling from farm to region.
abstract: Farm system and nutrient budget models are increasingly being used to inform and evaluate policy options on the impacts of land use change on regional environmental and economic performance. In this study, the common approach of up-scaling representative farm systems to a regional scale, with a limited input of resource information, was compared with a new approach that links a geospatial land resource information data base (NZLRI, Agribase™) that includes independent estimates of the productive capacity of land parcels, with individual farm-scale simulation (Farmax® Pro and Farmax® Dairy Pro) and nutrient budgeting models (Overseer®). The Southland region of New Zealand, which is currently undergoing enormous land use change, was used as a case study. Model outputs from the new approach showed increased profit of about 75% for the region if the current land area under dairying increases from 16% to 45%, with the shift to dairy constrained to high pasture production classes only. Environmental impacts associated with the change were substantial, with nitrate leaching estimated to increase by 35% and greenhouse gas emissions by 25%. Up-scaling of representative farm systems to the regional scale with limited input of resource information predicted lower potential regional profit and higher N leaching from dairy conversion. The new approach provides a farm scale framework that could easily be extended to include different systems, different levels of farming performance and the use of mitigation technologies.
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand. Electronic address: iris.vogeler@agresearch.co.nz.
authors.forename: Iris
authors.initials: I
authors.lastname: Vogeler
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Vibart
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
authors.forename: Alec
authors.initials: A
authors.lastname: Mackay
authors.affiliation: AgResearch, Lincoln Research Centre, Lincoln, Lincoln, New Zealand.
authors.forename: Samuel
authors.initials: S
authors.lastname: Dennis
authors.affiliation: AgResearch Limited, Ruakura Research Centre, Hamilton, New Zealand.
authors.forename: Vicki
authors.initials: V
authors.lastname: Burggraaf
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
authors.forename: Josef
authors.initials: J
authors.lastname: Beautrais
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D004777:Environment; D004784:Environmental Monitoring / Q000379:methods*; D015233:Models, Statistical; D009520:New Zealand; D009566:Nitrates / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D009566:Nitrates; D012989:Soil Pollutants
keywords: Dairying; Farmax® Pro and Farmax® Dairy Pro; Land conversion; Overseer®; Sheep and beef