The dairy industry is a significant contributor to the New Zealand economy. Improving dairy productivity while meeting appropriate environmental standards is necessary if the New Zealand economy is to grow sustainably. In this paper, a two–stage data envelopment analysis (DEA) technique was employed to assess the combined environmental and economic performance of dairy farms (i.e., eco-efficiency). A sample of 108 farms from a survey carried out in 2011-12 across all regions of New Zealand was used to analyse the eco-efficiency of dairy farms. Survey data on milk solid production was used to estimate economic performance, while data on greenhouse gas (GHG) emissions and nutrient leaching were used to estimate environmental performance. Other information in the survey such as geophysical characteristics and management practices that could indirectly affect the ecoefficiency of the dairy farms was also incorporated in the analysis. In the first stage of our analysis, an eco-efficiency score for each farm was estimated using directional distance function with restrictions in environmental outputs. In the second stage, the effect of the geophysical characteristics and management practices on the calculated eco-efficiency scores were then estimated using an integrated truncated regression and bootstrapping procedure. The results show that, on average, a reduction of 27% in environmental externalities was possible while maintaining the same level of output. GHG emissions, nitrogen leaching, and phosphorous loss were excessive and inefficient. Adopting irrigation and on-farm management practices (e.g., feed-pad, in-shed feeding, and wintering-pad) improved efficiency. The few dairy farms located on hilly or sloped land were found to be less efficient than those on flat land. Environmental policies applied to dairy sector have the potential to reduce GHG emission, nitrogen leaching, and phosphorous loss by 3.45 million tonnes, 20,610 tonnes, and 366 tonnes, respectively.

中文翻译：

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评估新西兰奶牛养殖生态效率：两阶段数据包络分析

乳制品业是新西兰经济的重要贡献者。如果新西兰经济要实现可持续增长，就必须在满足适当环境标准的同时提高乳制品生产力。在本文中，采用两阶段数据包络分析（DEA）技术来评估奶牛场的综合环境和经济绩效（即生态效率）。2011-12 年在新西兰所有地区进行的一项调查中的 108 个农场样本用于分析奶牛场的生态效率。关于乳固体生产的调查数据用于估计经济绩效，而有关温室气体 (GHG) 排放和养分浸出的数据用于估计环境绩效。调查中的其他信息，例如可能间接影响奶牛场生态效率的地球物理特征和管理实践，也被纳入分析。在我们分析的第一阶段，使用定向距离函数估算每个农场的生态效率得分，并限制环境输出。在第二阶段，地球物理特征和管理实践对计算的生态效率分数的影响然后使用集成的截断回归和引导程序进行估计。结果表明，平均而言，在保持相同产出水平的情况下，环境外部性减少 27% 是可能的。温室气体排放、氮浸出和磷损失过多且效率低下。采用灌溉和农场管理实践（例如，饲养场、棚内饲养和越冬场）提高了效率。发现位于丘陵或坡地的少数奶牛场效率低于平地的奶牛场。应用于乳制品行业的环境政策有可能分别减少 345 万吨、20,610 吨和 366 吨的温室气体排放、氮浸出和磷损失。