Measuring the Environmental Impacts of Agriculture: Use and Management of Nutrients

Keywords: Nutrient use, nitrogen balances, nutrient management, nutrient plans, nutrient soil tests, OECD countries.

The use of nutrients, such as nitrogen and phosphorus, are essential to agricultural production and in raising productivity, but a surplus of nutrients in excess of crop needs can lead to nutrient emissions. These emissions can potentially be a source of environmental damage to water and air quality, and contribute to global warming.

Equally, if nutrients are removed from arable farming systems and not replenished, a nutrient deficiency may develop, leading to declining soil fertility and yields. In the long term, this leads to soil degradation and may impair agricultural sustainability.

Many OECD countries have established goals to reduce nutrient emissions, closely linked to the need for agriculture to comply with standards for nitrate and phosphate emissions into aquatic environments. A number of international agreements also aim to limit transboundary nutrient emissions, including emissions from agriculture into rivers, marine waters and the atmosphere.

OECD countries are developing a set of agri-environmental indicators to monitor the impact of agriculture on the environment and provide a tool for analysis of related agricultural and environmental policies. Indicators of nitrogen balances and farm nutrient management practices are part of the OECD set of agri-environmental indicators.

The trend in nitrogen balance surpluses over the last decade is downward or constant for most OECD countries, which suggests that the potential environmental impact from agricultural nitrogen emissions is decreasing or stable. Many OECD countries have also developed and use nutrient management plans, while soil nutrient tests are conducted in most countries.

Kevin Parris and Laetitia Reille, Environment Division, Agriculture Directorate, OECD, Paris, France

31 pages, 3 tables, 7 figures, 51 refs.