In this publication we review recent research and understandings of nutrient flows and losses, and management practices on grazed pastoral farms in New Zealand. Developments in nutrient management principles in recent years have seen a much greater focus on practices and technologies that minimise the leakage of nutrients, especially nitrogen (N) and phosphorus (P), from farms to the wider environment. This has seen farm nutrient management planning shift from a relatively small set of procedures designed to optimise fertiliser application rates for pasture and animal production to a comprehensive whole-farm nutrient management approach that considers a range of issues to ensure A07001;

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The dairy industry in New Zealand is a significant contributor (7% of GDP) to the national economy. Major current issues for the industry are the lack of cheap, highly-nutritive value feed for cows of high genetic merit for milk yield; the poorer reproductive capacity of these high merit Holstein-Friesian cows; the quantity and skill of farm labour; and the environmental consequences of intensive dairy farming. The industry has responded to these challenges in the following ways. Increased nitrogen fertiliser use has given increased pasture yields, but also increased nitrate leaching and nitrous oxide emission from farms, which in turn has led to research on wintering pads, diet modification and nitrification inhibitors to reduce N losses to the environment. Increased use of supplementary feeds has given improved milk yield per cow, but also increased total farm variable costs, labour requirements and nutrient losses, which A07006;

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Water quality monitoring in Toenepi Stream, New Zealand, started in 1995 in a study of dairy farming influences on lowland stream quality and has continued since then with brief interruptions. Surveys have provided information about changes in farm and soil management practices as they relate to environmental sustainability. Although average water quality in Toenepi Stream has changed little during 1995-2004, there have been some notable improvements. Water clarity measured by black disc has improved from 0.6m to 1.5m, and median ammonia-N and nitrate-N concentrations have declined by 70% and 57%, respectively. The frequency and magnitude of extreme concentrations have declined-most notably for nitrogen (N) forms, which also had decreased mean values. Specific yields for suspended solids (SS) and phosphorus (P) forms in 2002-04 were 47-67% of 1995-97 values, mainly because of lower water yields. Reduced specific yields for N forms in 2002-04 (34-37% of 1995-97 yields) were also attributable to lower mean concentrations in stream water. Faecal bacteria concentrations have not abated and are on average 2-3 times recommended guideline values for contact recreation. Fewer dairy farms and an increased proportion irrigating dairyshed effluent to land, rather than discharging it to the stream via twopond systems, were likely causes of improvement in water quality. Water quality targets were developed for Toenepi Stream to achieve contact recreation criteria for the Piako River (downstream) and for intrinsic habitat values for Toenepi Stream. A range of mitigation measures has been formulated to meet these targets, but substantial uptake of sustainable farming practices is needed to improve water quality in Toenepi Stream.