title: A regional assessment of the cost and effectiveness of mitigation measures for reducing nutrient losses to water and greenhouse gas emissions to air from pastoral farms.
abstract: Using a novel approach that links geospatial land resource information with individual farm-scale simulation, we conducted a regional assessment of nitrogen (N) and phosphorous (P) losses to water and greenhouse gas (GHG) emissions to air from the predominant mix of pastoral industries in Southland, New Zealand. An evaluation of the cost-effectiveness of several nutrient loss mitigation strategies applied at the farm-scale, set primarily for reducing N and P losses and grouped by capital cost and potential ease of adoption, followed an initial baseline assessment. Grouped nutrient loss mitigation strategies were applied on an additive basis on the assumption of full adoption, and were broadly identified as 'improved nutrient management' (M1), 'improved animal productivity' (M2), and 'restricted grazing' (M3). Estimated annual nitrate-N leaching losses occurring under representative baseline sheep and beef (cattle) farms, and representative baseline dairy farms for the region were 10 ± 2 and 32 ± 6 kg N/ha (mean ± standard deviation), respectively. Both sheep and beef and dairy farms were responsive to N leaching loss mitigation strategies in M1, at a low cost per kg N-loss mitigated. Only dairy farms were responsive to N leaching loss abatement from adopting M2, at no additional cost per kg N-loss mitigated. Dairy farms were also responsive to N leaching loss abatement from adopting M3, but this reduction came at a greater cost per kg N-loss mitigated. Only dairy farms were responsive to P-loss mitigation strategies, in particular by adopting M1. Only dairy farms were responsive to GHG abatement; greater abatement was achieved by the most intensified dairy farm system simulated. Overall, M1 provided for high levels of regional scale N- and P-loss abatement at a low cost per farm without affecting overall farm production, M2 provided additional N-loss abatement but only marginal P-loss abatement, whereas M3 provided the greatest N-loss abatement, but delivered no additional P abatement, and came at a large financial cost to farmers, sheep and beef farmers in particular. The modelling approach provides a farm-scale framework that can be extended to other regions to accommodate different farm production systems and performances, capturing the interactions between farm types, land use capabilities and production levels, as these influence nutrient losses and GHG emissions, and the effectiveness of mitigation strategies.
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand. Electronic address: Ronaldo.Vibart@agresearch.co.nz.
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Vibart
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
authors.forename: Iris
authors.initials: I
authors.lastname: Vogeler
authors.affiliation: AgResearch, Lincoln Research Centre, Lincoln, New Zealand.
authors.forename: Samuel
authors.initials: S
authors.lastname: Dennis
authors.affiliation: PwC, Wellington, New Zealand.
authors.forename: William
authors.initials: W
authors.lastname: Kaye-Blake
authors.affiliation: AgResearch, Invermay Research Centre, Mosgiel, New Zealand.
authors.forename: Ross
authors.initials: R
authors.lastname: Monaghan
authors.affiliation: AgResearch, 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
authors.affiliation: AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
authors.forename: Alec
authors.initials: A
authors.lastname: Mackay
mesh_terms: D000383:Agriculture / Q000191:economics / Q000379:methods; D000818:Animals; D002245:Carbon Dioxide / Q000032:analysis*; D002417:Cattle; D003247:Conservation of Natural Resources / Q000191:economics* / Q000379:methods; D003362:Cost-Benefit Analysis; D017752:Greenhouse Effect / Q000517:prevention & control*; D009520:New Zealand; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012756:Sheep; D018505:Waste Management / Q000191:economics / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D009566:Nitrates; D014867:Water; D002245:Carbon Dioxide; D010758:Phosphorus; D009584:Nitrogen
keywords: Beef; Dairy; Greenhouse gas emissions; Nitrogen losses; Phosphorous losses; Sheep