The biggest environmental threat comes from pig manure. A sow producing 22 pigs for slaughter at 90 kg “liveweight” can excrete around 100 kg of nitrogen and 18-20 kg of phosphorous per year. How this manure is handled and disposed of is a crucial environmental question. Farms can use animal manure as fertiliser, but specialised pig farms simply produce too much of it. Disposal of pig manure is especially problematic in the population-dense countries of the Netherlands and Belgium, as well as in Denmark, Japan and Korea, among others. In the US, a number of important pig-producing counties have manure nitrogen production levels that exceed the assimilative capacity of all the county’s crop and pasture land. Impacts on the environment from pig manure include the degradation of aquatic ecosystems, and air pollution from odours and ammonia emissions, as well as impacts on soil quality and biodiversity.

Regulations can also help limit the environmental impact of pig production. But while regulations on manure management have got stronger, differences between countries have not yet had any significant impact on trade patterns. This is where trade policy comes in. Those countries with the highest levels of support payment for pig meat, mostly through tariffs and export subsidies, are also those with the greatest risk of nitrogen water pollution from pig production. However, Agriculture, Trade and the Environment: The Pig Sector shows that further trade liberalisation is likely to strengthen market trends in the pig sector, slowing production in OECD European and Asian countries where the environmental risk is the greatest. Maybe pigs can be outsmarted after all.

©OECD Observer No 239, September 2003