ABSTRACT

The Canterbury Region of New Zealand has undergone rapid and significant land use intensification over the last three decades resulting in a substantial increase of nitrate-nitrogen leached to the environment. In this article, we determined the nitrate grey water footprint of milk, which is the amount of water needed to dilute nitrogen leached past the root zone to meet different receiving water nitrate standards per milk production unit. Our analysis revealed the nitrate grey water footprint for Canterbury ranged from 433 to 11,110 litres of water per litre of milk, depending on the water standards applied. This footprint is higher than many estimates for global milk production, and reveals that footprints are very dependent on inputs included in the analyses and on the water quality standards applied to the receiving water. The extensive dairy farming in Canterbury is leading to significant pollution of the region’s groundwater, much of which is used for drinking water. Dairy farming at this intensity is unsustainable and if not reduced could pose a significant risk to human health and the market perception of the sustainability of the New Zealand dairy industry and its products.

摘要

在过去的三十年里，新西兰坎特伯雷地区经历了迅速而显着的土地利用集约化，导致渗入环境中的硝酸盐-氮大量增加。在本文中，我们确定了牛奶的硝酸盐灰水足迹，即稀释从根区浸出的氮以满足每个牛奶生产单位的不同接收水硝酸盐标准所需的水量。我们的分析显示，坎特伯雷的硝酸盐灰水足迹范围为每升牛奶 433 至 11,110 升水，具体取决于所应用的水标准。这一足迹高于全球牛奶生产的许多估计值，并表明足迹非常依赖于分析中包含的投入和适用于接收水的水质标准。坎特伯雷广泛的奶牛养殖导致该地区地下水严重污染，其中大部分用于饮用水。这种强度的奶牛养殖是不可持续的，如果不减少，可能会对人类健康和市场对新西兰奶业及其产品可持续性的看法构成重大风险。