AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
J Environ Manage. 2015 Jun 1;156:276-89. doi: 10.1016/j.jenvman.2015.03.041. Epub 2015 Apr 17.
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.
利用一种将地理空间土地资源信息与个体农场规模模拟联系起来的新方法，我们对新西兰南地地区主要畜牧业的氮（N）和磷（P）向水体和温室气体（GHG）向空气的损失进行了区域评估。在对农场规模的几种养分损失缓解策略进行成本效益评估之后，我们首先设定了主要用于减少 N 和 P 损失的策略，并按资本成本和潜在采用难度进行了分组。在完全采用的假设下，基于添加的方式应用分组养分损失缓解策略，并将其广泛定义为“改善养分管理”（M1）、“提高动物生产力”（M2）和“限制放牧”（M3）。估计在该地区代表性的基础绵羊和牛肉（牛）农场以及代表性的基础奶牛场中，每年发生的硝酸盐-N 淋溶损失分别为 10±2 和 32±6 kg N/ha（平均值±标准差）。绵羊和牛肉以及奶牛农场都对 M1 中的 N 淋溶损失缓解策略有反应，每减少 1 kg N 的成本较低。只有奶牛农场对 M2 中减少 N 淋溶损失有反应，每减少 1 kg N 无需额外成本。奶牛农场对 M3 中减少 N 淋溶损失也有反应，但减少 1 kg N 的成本更高。只有奶牛农场对 P 损失缓解策略有反应，特别是通过采用 M1。只有奶牛农场对 GHG 减排有反应；模拟的最集约化奶牛农场系统实现了更大的减排。总体而言，M1 在不对农场整体生产产生影响的情况下，以低单位农场成本实现了高水平的区域规模 N 和 P 减排；M2 提供了额外的 N 减排，但只有少量的 P 减排；而 M3 提供了最大的 N 减排，但对农民来说没有额外的 P 减排，而且成本很高，特别是对绵羊和牛肉农民来说。该建模方法提供了一个农场规模框架，可以扩展到其他地区，以适应不同的农场生产系统和表现，捕捉农场类型、土地利用能力和生产水平之间的相互作用，因为这些因素会影响养分损失和 GHG 排放以及缓解策略的有效性。
