Nutrient management in New Zealand pastures— recent developments and future issues

Abstract

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 both farm productivity and environmental outcomes are achieved. These include consideration of factors such as multiple sources of nutrient imports to farms, the optimal re‐use and re‐distribution of nutrient sources generated within the farm (such as farm dairy effluent), identification of the risks associated with applying various nutrient forms to contrasting land management units, and an econometric evaluation of farm fertilisation practices. The development of nutrient budgeting and econometric decision support tools has greatly aided putting these more complex whole‐farm nutrient management systems into practice. Research has also identified a suite of mitigation systems and technological measures that appear to be able to deliver substantial reductions in nutrient losses from pastoral farms. However, issues of cost, complexity, compatibility with the current farm system, and a perceived uncertainty of actual environmental benefits are identified as key barriers to adoption of some of these technologies. Farmers accordingly identified that their main requirement for improved nutrient management planning systems was flexibility in how they would meet their environmental targets. The provision of readily discernible information and tools defining the economic and environmental implications of a range of proven management or mitigation practices is a key requirement to achieve this.