DairyNZ Ltd., Private Bag 3221, Hamilton 3240, New Zealand.
J Environ Manage. 2012 Jan;93(1):44-51. doi: 10.1016/j.jenvman.2011.08.013. Epub 2011 Sep 18.
As the scope and scale of New Zealand (NZ) dairy farming increases, farmers and the industry are being challenged by Government and the New Zealand public to address growing environmental concerns. Dairying has come under increasing scrutiny from local authorities tasked with sustainable resource management. Despite recent efforts of farmers and industry to improve resource use efficiency, there is increasing likelihood of further regulatory constraints on water use and nutrient management. This study uses available data on farm-gate nitrogen (N) surpluses and milk production from the Waikato, New Zealand's largest dairying region, together with a farm scale modeling exercise, to provide a perspective on the current situation compared to dairy farms in Europe. It also aims to provide relevant guidelines for N surpluses and efficiencies under NZ conditions. Waikato dairy farms compare favorably with farms in Europe in terms of N use efficiency expressed as L milk/kg farm-gate N surplus. Achievable and realistic good practice objectives for Waikato dairy farmers could be 15,000 L milk/ha (1200 kg milk fat plus protein/ha) with a farm-gate N surplus of 100 kg/ha giving an eco-efficiency (L milk/kg N surplus) of 150, and long-term average nitrate leaching losses of approximately 25-30 kg/ha/yr. This can be achieved by increasing the N conversion efficiency through lower replacement rates (16 versus 22%), lower stocked (< 3 cows/ha) high genetic merit cows (30 L milk/day at peak) milked for longer (277 versus 240 days), feeding effluent-irrigated, home-grown, low-protein supplements to cows on high-protein, grass-clover pastures to dilute N concentration in the diet, removing some of the urinary N from the paddocks during critical times by standing cows on a loafing pad for part of the day, and through lower N fertilizer rates (50-70 kg/ha/yr compared to the norm of 170-200 kg/ha/yr) and using a nitrification inhibitor and gibberellins to boost pasture growth and the former to reduce N leaching.
随着新西兰（NZ）奶牛养殖业规模的扩大，农民和该行业面临着政府和新西兰公众的挑战，需要解决日益严重的环境问题。奶牛养殖受到负责可持续资源管理的地方当局的严格审查。尽管农民和行业最近努力提高资源利用效率，但水和养分管理的进一步监管限制的可能性越来越大。本研究利用新西兰最大的奶牛养殖地区怀卡托的农场门口氮（N）盈余和牛奶产量的现有数据，以及农场规模模拟，提供了与欧洲奶牛场相比的现状观点。它还旨在为新西兰条件下的 N 盈余和效率提供相关指南。怀卡托奶牛场在 N 利用效率方面与欧洲的农场相比表现出色，以农场门口 N 盈余表示的 L 牛奶/kg 农场门口 N 盈余。怀卡托奶农可实现且切实可行的良好实践目标可以是 15000 L 牛奶/公顷（1200 kg 牛奶脂肪加蛋白质/公顷），农场门口 N 盈余 100 kg/公顷，生态效率（L 牛奶/kg N 盈余）为 150，长期平均硝酸盐淋溶损失约为 25-30 kg/ha/yr。这可以通过提高 N 转化效率来实现，方法是降低替代率（16 对 22%），降低存栏量（<3 头/公顷）的高遗传潜力奶牛（高峰时 30 L 牛奶/天），延长挤奶时间（277 天对 240 天），在高蛋白三叶草牧场上用污水灌溉、自产、低蛋白补充料喂养奶牛，以稀释饮食中的 N 浓度，在关键时期将部分尿液 N 从牧场上清除，通过让奶牛站在一天中的一部分时间里的休息垫上，以及通过降低 N 肥料用量（50-70 kg/ha/yr 与 170-200 kg/ha/yr 的常规用量相比）和使用硝化抑制剂和赤霉素来促进牧草生长和前者来减少 N 淋溶。
